Preliminary guideline for the determination of buffer zones for rivers, wetlands and estuaries

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TT 610/14
TT 610/14 - Preliminary Guideline for the Determination of Buer Zones for Rivers, Wetlands and Estuaries
Preliminary Guideline for the
Determination of Buffer Zones
for Rivers, Wetlands and Estuaries
CONSOLIDATED REPORT
DM Macfarlane, IP Bredin, JB Adams, MM Zungu, GC Bate & CWS Dickens

PRELIMINARY GUIDELINE FOR THE
DETERMINATION OF BUFFER ZONES FOR
RIVERS, WETLANDS AND ESTUARIES
Consolidated Report
Report to the
WATER RESEARCH COMMISSION
by
INSTITUTE OF NATURAL RESOURCES
DM Macfarlane2, IP Bredin1, JB Adams3, MM Zungu1, GC Bate3 and CWS Dickens1
1 Institute of Natural Resources, Pietermaritzburg, South Africa
2 Eco-pulse Environmental Consulting Services, Hilton, South Africa
3 Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
WRC Report No. TT 610/14
September 2014

Preliminary Guideline for the Determination of Buffer Zones 2014
ii
OBTAINABLE FROM
Water Research Commission
Private Bag X03
Gezina 0031
South Africa
orders@wrc.org.za or download from www.wrc.org.za
The publication of this report emanates from a project entitled: Development of a methodology to
determine appropriate buffer zones for developments associated with wetlands, rivers and estuaries
(WRC Project No. K5/2200).
DISCLAIMER
This report has been reviewed by the Water Research Commission (WRC) and approved for
publication. Approval does not signify that the contents necessarily reflect the views and policies of
the WRC, nor does mention of trade names or commercial products constitute endorsement or
recommendation for use.
RECOMMENDED CITATION
Macfarlane, D.M., Bredin, I.P., Adams, J.B., Zungu, M.M., Bate, G.C. and Dickens, C.W.S. 2014.
Preliminary guideline for the determination of buffer zones for rivers, wetlands and estuaries. Final
Consolidated Report. WRC Report No TT 610/14, Water Research Commission, Pretoria.
ISBN 978-1-4312-0590-5
Printed in the Republic of South Africa
© Water Research Commission

Preliminary Guideline for the Determination of Buffer Zones 2014
iii
EXECUTIVE SUMMARY
South Africa’s aquatic ecosystems are under increasing pressure, with impacts such as regulation
of flow by impoundments, pollution, over-extraction of water, and the breakdown of natural bio-
geographical barriers all affecting the ecological condition of these resources. The need for
preventative measures to prevent further degradation of these resources has therefore been
highlighted. It is in this context that establishment of buffer zones to rivers, estuaries and wetlands
can play a meaningful role in reducing impacts to aquatic resources and in so doing, protect the
range of goods and services that these resources provide to society.
This report highlights the complete process that has been followed in the development of a
preliminary guideline for the determination of buffer zones for rivers, wetlands and estuaries.
What are buffer zones?
Definitions of buffer zones are variable, depending on their purpose. Buffer zones have been used
in land-use planning to protect natural resources and limit the impact of one land-use on another.
This project specifically looks at aquatic buffer zones which are typically designed to act as a barrier
between human activities and sensitive water resources thereby protecting them from adverse
negative impacts.
Why are buffer zones regarded as important?
Buffer zones associated with water resources have been shown to perform a wide range of
functions, and on this basis, have been proposed as a standard measure to protect water resources
and associated biodiversity. These functions include:
• Maintaining basic aquatic processes;
• Reducing impacts on water resources from upstream activities and adjoining land uses;
• Providing habitat for aquatic and semi-aquatic species;
• Providing habitat for terrestrial species; and
• A range of ancillary societal benefits.
What buffer zones don’t do?
Despite the range of functions potentially provided by buffer zones, buffer zones are far from a
“silver bullet” that addresses all water resource related problems. Indeed, buffers can do little to
address some impacts such as hydrological changes caused by stream flow reduction activities (i.e.
changes in flow brought about by abstractions or upstream impoundments). Buffer zones are also
not the appropriate tool for militating against point-source discharges (e.g. sewage outflows), which
can be more effectively managed by targeting these areas through specific source-directed controls.
Contamination or use of groundwater is also not well addressed by buffer zones and requires
complementary approaches such as controlling activities in sensitive groundwater zones.
Conceptual framework – design criteria applied
In developing an approach for buffer zone determination, a number of key decisions were made that
informed the development of the method, these include:
• Levels of user expertise;
• Precautionary principle;
• Predictability and administration;

Preliminary Guideline for the Determination of Buffer Zones 2014
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• Data collection and assessment; and
• Buffer widths should be tailored according to risk.
The selection of an appropriate approach to setting buffer zones
Three generic approaches were identified in the literature review, these included: the fixed-width,
modified fixed-width, and variable width approach. The modified fixed-width approach was regarded
as most appropriate for the South African context. This was principally due to the need to develop a
tool that could be applied across different levels, while maintaining a level of predictability and
consistency between approaches. The method outlined in this document therefore proposes highly
conservative buffer widths based on generic relationships for broad-scale assessments but allows
these to be modified based on more detailed site-level information. Resultant buffers therefore
range from highly conservative, fixed widths for different land uses at a desktop level to buffers that
are modified based on a more thorough understanding of the water resource and specific site
characteristics.
The assessment procedure
The assessment procedure is largely the core of the document. An eight step assessment
procedure provides the user with a step-by-step approach for determining appropriate buffer zones,
or rather setback areas that take into consideration the following:
• The aquatic impact buffer zone;
• Potential core habitats;
• Potential ecological corridors; and
• Relevant additional mitigating measures.

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Determining appropriate management measures for aquatic impact buffer zones
Determining appropriate management measures for aquatic impact buffer zones is largely
dependent on the threats associated with the proposed activity adjacent to the water resource.
These threats include:
• Increases in sedimentation and turbidity;
• Increased nutrient inputs;
• Increased inputs of toxic organic and heavy metal contaminants; and
• Pathogen inputs.
Determining appropriate management measures for biodiversity conservation
A review of international literature found that in general significantly larger buffers are required for
the protection of biodiversity that is dependent on a water resource, in comparison to those
adequate for providing water quality protection. Many aquatic and semi-aquatic species depend
upon water resources for only portions of their life cycles and they require terrestrial habitats
adjacent to the water resources to meet all their life needs. Without access to appropriate terrestrial
habitat and the opportunity to move safely between habitats across a landscape, it will not be
possible to maintain viable populations of many species. Therefore, core habitats and corridors
need to be developed for the protection of species or habitats of conservation concern.
Additional aspects requiring consideration to ensure effective management of setback areas
There are many aspects that need to be considered to ensure that, once established, setback areas
continue to provide their required functions. Overlooking these aspects highlighted below may result
in the degradation of setback areas over time:
• Regulating aquatic impact buffer zones;
• Aquatic impact buffer zone demarcation;
• Aspects that may require the expansion of the aquatic impact buffer zone;
• Maintenance of supporting mitigation measures;
• Buffer zones in urban areas;
• Rehabilitation or enhancement of buffer zones; and
• Buffer zones and climate change.
Conclusions and recommendations
The assessment procedure detailed in this report, as well as the management practices that need to
be taken into consideration, provide the guidelines for determining and managing appropriate buffer
zones. The ‘Buffer Zone Tools’ developed in conjunction with this report provide the user with the
primary tool for determining appropriate buffer zones (included on the accompanying CD). In
addition, the extensive supporting documents provided as annexures to the report, either in
hardcopy or as electronic copies on the accompanying CD, provide extensive background
information.
A second phase to the project is required. This will include providing practitioners with an
opportunity to learn how to use the ‘Buffer Zone Tools’ developed, which will in turn allow for the
refinement of the preliminary guideline document and buffer zone tools to produce a scientifically
sound and well tested approach to determining buffer zones.

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ACKNOWLEDGEMENTS
The project team would like to thank all the people who made this project possible. Special thanks
to the Water Research Commission (WRC) for the funding and to Mr Bonani Madikizela, Dr Stanley
Liphadzi, and Ms Una Wium for facilitating and giving invaluable advice on the administration of the
project. The other members of the WRC Steering Committee are also acknowledged for their input
and guidance, namely: Mr Umesh Bahadur, Dr Alan Boyd, Mr Gerhard Diedericks, Ms Jane Eagle,
Ms Loraine Fick, Ms Ursula Franke, Mr Fanie Fourie, Ms Naomi Fourie, Ms Jeanne Gouws, Mr
David Kleyn, Dr Neels Kleynhans, Mr Anton Linstrom, Mr Hannes Marais, Mr Gary Marneweck, Dr
Heather Malan, Dr Steve Mitchell, Mr Piet Muller, Ms Natalie Newman, Dr Rodger Parsons, Prof
Kevin Rodgers, Dr Wietsche Roets, Mr Mark Rountree, Mr Jerry Theron, Ms Christa Thirion, Mr
Damian Walters, Ms Ronell Niemans, Prof Alan Whitfield, Mr Piet-Louis Grundling, Mr Kas
Hamman, and Ms Kristal Maze.
In addition, many other people contributed towards the development of the preliminary guideline
document, either through expert input to specific aspects, through attendance at meetings or
workshops or through direct feedback. Their contributions helped to improve the guidelines
developed. While it is not possible to acknowledge everyone individually, the following key thanks
are necessary:
• Dr Gordon O’Brien, for his contribution towards testing and developing the method for
assessing the sensitivity of rivers and streams.
• Mr Leo Quayle and Ms Pearl Gola, for their contribution towards developing the method for
determining the effectiveness of buffers at mitigating toxic contaminant threats. In addition,
Mr Leo Quayle also helped draft the guidelines for corridor design.
• Mr Adam Teixeira-Leite and Ms Meredith Cowie, for their contribution towards testing the
wetland and estuary buffer tools respectively.
• Mr Adam Teixeira-Leite, Dr Pete Goodman and Ms Christine Colvin, for their contributions
towards developing an initial draft method and model.
• Ms Naomi Fourie, for taking an active role in guiding the development of this method and
helping to convene key workshops.
• Dr Donovan Kotze, for providing feedback on key aspects of the method as it was developed
and for contributing towards the development of sensitivity criteria for wetland systems.
• Dr Mark Graham and Mr Gary De Winaar for sharing lessons learnt in the development of a
procedure for buffer zone determination for KZN Wildlife. They also provided constructive
input to the method and provided specific input in defining sensitivity criteria for rivers and
streams.
• Mr James Harvey, for compiling the information sheet for the Pickersgill’s Reed Frog.
• KZN Wildlife staff, for providing constructive feedback on the biodiversity guidelines and in
helping to draft species information sheets for a number of species.

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TABLE OF CONTENTS
EXECUTIVE SUMMARY ................................................................................................................................. iii
ACKNOWLEDGEMENTS ................................................................................................................................ vi
LIST OF TABLES ............................................................................................................................................. xi
LIST OF FIGURES .......................................................................................................................................... xii
ABBREVIATIONS USED IN THIS REPORT .............................................................................................. xiii
1. INTRODUCTION .................................................................................................................................. 1
1.1. Purpose of this report ........................................................................................................................... 1
1.2. What are buffer zones? ........................................................................................................................ 1
1.3. Why are buffer zones regarded as important? ................................................................................. 2
1.4. What buffers don’t do ........................................................................................................................... 4
2. CONCEPTUAL FRAMEWORK FOR DEVELOPING A BUFFER ZONE METHOD .................. 4
2.1. Design criteria used to inform the development of a method and model for buffer
determination ..................................................................................................................................................... 4
2.2. Selection of an appropriate approach for setting buffers ................................................................ 5
2.3. Designing an approach to cater for the full range of buffer functions ........................................... 6
2.4. Developing an approach in the absence of a formally structured assessment framework ....... 7
3. THE ASSESSMENT PROCEDURE .................................................................................................. 8
4. STEP 1: DEFINE OBJECTIVES AND SCOPE TO DETERMINE THE MOST APPROPRIATE
LEVEL OF THE ASSESSMENT .................................................................................................................. 10
4.1. Define objectives and scope of the assessment ............................................................................ 10
4.2. Determine the most appropriate level of assessment ................................................................... 10
5. STEP 2: MAP AND CATEGORIZE WATER RESOURCES IN THE STUDY AREA ............... 12
5.1. Map water resource boundaries ....................................................................................................... 12
5.2. Map the line from which aquatic impact buffer zones will be delineated ................................... 15
5.3. Identify water resource type .............................................................................................................. 18
6. STEP 3: REFER TO THE DWA MANAGEMENT OBJECTIVES FOR MAPPED WATER
RESOURCES OR DEVELOP SURROGATE OBJECTIVES .................................................................. 20
6.1. Determine the Present Ecological State (PES) and anticipated trajectory of water resource
change .............................................................................................................................................................. 21
6.2. Determine the Importance and sensitivity of the water resources .............................................. 23
6.2.1. Assessing Ecological Importance and Sensitivity .......................................................................... 23
6.2.2. Assessing Social Importance ............................................................................................................ 24

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6.2.3. Assessing Economic Importance ..................................................................................................... 25
6.3. Determine the management objectives for water resources ........................................................ 25
6.3.1. With classification ............................................................................................................................... 26
6.3.2. Without classification .......................................................................................................................... 26
7. STEP 4: ASSESS THE RISKS FROM PROPOSED DEVELOPMENTS AND DEFINE
MITIGATION MEASURES NECESSARY TO PROTECT MAPPED WATER RESOURCES IN THE
STUDY AREA ................................................................................................................................................. 28
7.1. Undertake a risk assessment to assess the potential impacts of planned activities on water
resources ......................................................................................................................................................... 28
7.2. Evaluate the threats posed by land use / activities on water resources .................................... 29
7.3. Integrate climatic factors into the threat assessment .................................................................... 34
7.4. Assess the sensitivity of water resources to threats posed by lateral land-use impacts ......... 37
7.4.1. Assessing the sensitivity of wetlands to lateral land-use inputs .................................................. 38
7.4.2. Assessing the sensitivity of estuaries to lateral inputs .................................................................. 38
7.4.3. Assessing the sensitivity of rivers and streams to lateral inputs ................................................. 39
7.5. Assess the sensitivity of important biodiversity elements to threats posed by lateral land-use
impacts ............................................................................................................................................................. 39
7.6. Determine the risk posed by proposed activities on water resources ........................................ 39
7.7. For selected impacts, determine desktop aquatic impact buffer requirements ......................... 41
7.8. Determine preliminary aquatic impact buffer zone widths required to mitigate risks identified ..
............................................................................................................................................................... 43
7.8.1. Increased sedimentation and turbidity ............................................................................................. 44
7.8.2. Increased nutrient inputs from lateral inputs ................................................................................... 44
7.8.3. Increased toxic contaminants from lateral inputs ........................................................................... 45
7.8.4. Increased pathogen inputs from lateral sources ............................................................................ 46
7.9. Refine preliminary buffer requirements based on site-based investigations ............................. 46
7.10. Where appropriate, identify additional mitigation measures and refine aquatic impact buffer
width accordingly ............................................................................................................................................ 48
7.10.1. ......... Review and refine aquatic impact buffer requirements to cater for practical management
considerations ................................................................................................................................................. 49
7.11. Evaluate aquatic impact buffer zone requirements in light of management objectives ........... 50
8. STEP 5: ASSESS RISKS POSED BY PROPOSED DEVELOPMENT ON BIODIVERSITY
AND IDENTIFY MANAGEMENT ZONES FOR BIODIVERSITY PROTECTION ................................. 51
8.1. Undertake a desktop assessment to determine whether important biodiversity elements are
likely to be present .......................................................................................................................................... 52
8.2. If important biodiversity elements are likely to be present, undertake a survey to verify them
and establish the need for site-based conservation efforts ...................................................................... 54

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8.3. Identify core areas required to protect any important biodiversity features ............................... 55
8.4. Adjust aquatic impact buffer requirements based on sensitivities of any important biota
identified ........................................................................................................................................................... 55
8.5. Identify any additional biodiversity buffer requirements ................................................................ 56
8.6. Assess the need for connectivity and identify suitable fine-scale corridors where appropriate .
............................................................................................................................................................... 57
9. STEP 6: DELINEATE AND DEMARCATE RECOMMENDED SETBACK REQUIREMENTS 57
9.1. Delineate the boundary of water resources .................................................................................... 58
9.2. Map required for aquatic impact buffer zones ................................................................................ 58
9.3. Map setback requirements for water resource protection ............................................................ 58
9.4. Map zones for biodiversity protection .............................................................................................. 60
9.5. Ensure that any additional factors have been considered before finalizing setback
requirements .................................................................................................................................................... 60
9.6. Map recommended setback requirement based on the maximum width for water resource,
biodiversity protection and additional considerations ................................................................................ 61
9.7. Finalize proposed setback requirements with motivations for any deviations from
recommended requirements ......................................................................................................................... 61
10. STEP 7: DOCUMENT MANAGEMENT MEASURES NECESSARY TO MAINTAIN THE
EFFECTIVENESS OF SETBACK AREAS ................................................................................................. 61
10.1. Document management measures to maintain or improve the functionality of aquatic impact
buffers ............................................................................................................................................................... 62
10.1.1.Buffer zone vegetation ....................................................................................................................... 62
10.1.2.Soil characteristics .............................................................................................................................. 63
10.1.3.Topography of the buffer zone ......................................................................................................... 64
10.2. Document management measures to safeguard species and habitat over the long-term ...... 64
10.2.1.Core habitat management ................................................................................................................. 65
10.2.2.Ecological corridor design and management ................................................................................. 66
10.3. Additional aspects requiring consideration to ensure effective management of setback
areas ............................................................................................................................................................... 67
10.3.1.Regulating aquatic impact buffer zones .......................................................................................... 67
10.3.2.Aquatic impact buffer zone demarcation ......................................................................................... 68
10.3.3.Aspects that may require the expansion of the aquatic impact buffer zone .............................. 68
10.3.4.Maintenance of supporting mitigation measures ........................................................................... 69
10.3.5.Buffer zones in urban areas .............................................................................................................. 69
10.3.6.Rehabilitation or enhancement of buffer zones ............................................................................. 70
10.3.7.Buffer zones and climate change ..................................................................................................... 70

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11. STEP 8: MONITOR IMPLEMENTATION OF BUFFER ZONES ................................................. 71
12. CONCLUSIONS AND RECOMMENDATIONS .............................................................................. 72
13. REFERENCES .............................................................................................................................. ...... 74
14. ANNEXURES ...................................................................................................................................... 81
Annexure 1 – Deliverable 1: Literature review (electronic copy only – refer to the CD provided) ..... 81
Annexure 2 – Deliverable 11: Practical testing (electronic copy only – refer to the CD provided) ..... 81
Annexure 3 – Range of management measures available to address threats posed to water
resources ......................................................................................................................................................... 81
Annexure 4 – National and/or sub-national (CAPE) priority estuaries (electronic copy only – refer to
the CD provided) ............................................................................................................................................. 88
Annexure 5 – Estuary importance scores for all South African estuaries (electronic copy only – refer
to the CD provided) ........................................................................................................................................ 88
Annexure 6 – Description of sectors and sub-sectors included in the threat assessment .................. 89
Annexure 7 – Specific limits set for evaluating different threat types assessed (electronic copy only –
refer to the CD provided) ............................................................................................................................... 99
Annexure 8 – Summary of Average Event Mean Concentrations (EMCs) for sectors & sub-sectors
(electronic copy only – refer to the CD provided) ...................................................................................... 99
Annexure 9 – Event Mean Concentrations (EMCs) for sectors & sub-sectors obtained from
international literature (electronic copy only – refer to the CD provided) ............................................... 99
Annexure 10 – Initial desktop threat ratings based on expert workshops (electronic copy only – refer
to the CD provided) ........................................................................................................................................ 99
Annexure 11 – Hydrological sensitivity analysis ...................................................................................... 100
Annexure 12 – Guidelines for assessing the sensitivity of wetlands to lateral land-use inputs ........ 114
Annexure 13 – Guideline for assessing the sensitivity of rivers and streams to impacts from lateral
land use inputs .............................................................................................................................................. 133
Annexure 14 – Guidelines for assessing the sensitivity of estuaries to lateral land-use inputs ....... 148
Annexure 15 – Development of rule-curves to link buffer efficiency to buffer width ........................... 158
Annexure 16 – Guidelines for refining buffer requirements based on site characteristics ................ 172
Annexure 17 – Overview of the mitigation measures tool ...................................................................... 189
Annexure 18 – Examples of biodiversity information sheets (electronic copy only – refer to the CD
provided) ........................................................................................................................................................ 190
Annexure 19 – Guidelines for corridor design (electronic copy only – refer to the CD provided) .... 190
Annexure 20 – Useful data layers (electronic copy only – refer to the CD provided)......................... 190

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LIST OF TABLES
Table 1. Summary of roles and associated functions provided by buffer zones ................................ 2
Table 2. Summary of the different levels of assessment for buffer zone determination ................. 11
Table 3. Minimum requirements for mapping the boundaries of water resources. .......................... 15
Table 4. Minimum requirements for mapping the line from which aquatic impact buffers will be
determined. ...................................................................................................................................................... 16
Table 5. Proposed classification system for estuaries (SANBI, 2009) ............................................... 18
Table 6. Proposed classification system for Rivers (adapted from SANBI, 2009 & Ollis et al.,
2013) ....................................................................................................................................................... 19
Table 7. Proposed classification system for inland wetlands (adapted from SANBI, 2009 & Ollis
et al., 2013) ...................................................................................................................................................... 19
Table 8. Generic ecological categories for Ecostatus components (modified from Kleynhans,
1996 & Kleynhans, 1999) .............................................................................................................................. 22
Table 9. Illustration of the summary of an EcoStatus assessment for a river system. .................... 22
Table 10. Generic EIS categories .......................................................................................................... 24
Table 11. Determining the management objective where the WRCS has been applied .............. 26
Table 12. Determining the management objective based on PES and importance of the water
resource. ................................................................................................................................................... 27
Table 13. List of Sectors and sub-sector land use classes / activities ............................................. 30
Table 14. Ratings used to evaluate the level of threat posed by diffuse surface runoff from
various land uses / activities located adjacent to water resources. ........................................................ 32
Table 15. Modifiers used to calculate a Climate Risk Score. ............................................................ 36
Table 16. Sensitivity classes used to guide the assessment of sensitivity of water resources to
lateral impacts. ................................................................................................................................................ 37
Table 17. Indicators used to assess the sensitivity of wetlands to lateral land use impacts ........ 38
Table 18. Indicators used to assess the sensitivity of estuaries to lateral land use impacts ........ 38
Table 19. Indicators used to assess the sensitivity of rivers and streams to lateral land use
impacts ................................................................................................................................................... 39
Table 20. Table used to integrate threat and sensitivity scores into a composite risk score as part
of the buffer zone model. ............................................................................................................................... 40
Table 21. Risk classes used in this assessment. ................................................................................ 40
Table 22. Summary of common threats posed by adjoining land uses / activities on water
resources and typical approaches to addressing them. Instances where buffer zones can play a
particularly important role are highlighted in blue. ..................................................................................... 41
Table 23. Guideline for linking buffer width with buffer zone effectiveness ..................................... 43
Table 24. Review of different buffer types and the recommended minimum buffer zone widths 49
Table 25. Guideline for identifying appropriate management and mitigation measures. .............. 50
Table 26. Key buffer functions provided by a core habitat. ................................................................ 55
Table 27. Description of key biodiversity buffer function .................................................................... 56
Table 28. Description of key biodiversity corridor function ................................................................. 57

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LIST OF FIGURES
Figure 1. Overview of the step-wise assessment process .................................................................. 9
Figure 2. Schematic diagram indicating the boundary of active channel and riparian habitat and
the areas potentially included in an aquatic impact buffer zone. ............................................................. 16
Figure 3. Classification of river channels (Adapted from DWAF, 2005) .......................................... 18
Figure 4. Illustration of the distribution of Ecological Categories on a continuum ......................... 22
Figure 5. Diagram illustrating how threat classes have been related to SLV & GLV limits. ......... 32
Figure 6. Mean annual precipitation (Adapted from Schulze et al., 2007) ...................................... 35
Figure 7. Rainfall intensity zones based on one day design rainfall over a two year return
(Adapted from Schulze et al., 2007) ............................................................................................................ 36
Figure 8. Relationship between (a) sediment removal efficiency and buffer width and (b) risk of
sediment inputs and buffer requirements used to calculate aquatic impact buffer requirements (m)
................................................................................................................................................... 44
Figure 9. Relationship between (a) nutrient removal efficiency and buffer width and (b) risk of
nutrient inputs and buffer requirements used to calculate aquatic impact buffer requirements. ........ 45
Figure 10. Relationship between (a) toxic metal removal efficiency and buffer width and (b) risk of
toxic metal inputs and buffer requirements used to calculate aquatic impact buffer requirements. .. 45
Figure 11. Relationship between (a) organic pollutants and pesticide removal efficiency and
buffer width and (b) risk of organic pollutants and pesticide inputs and buffer requirements used to
calculate aquatic impact buffer requirements. ............................................................................................ 46
Figure 12. Relationship between (a) pathogen removal efficiency and buffer width and (b) risk of
pathogen inputs and buffer requirements used to calculate aquatic impact buffer requirements. ..... 46
Figure 13. Cross-section through a slope adjacent a water resource indicating how buffer zone
widths should be measured. ......................................................................................................................... 58
Figure 14. Example 1: Map indicating the active channel, riparian zone, recommended aquatic
impact buffer zone and final recommended setback requirement for a proposed residential
development planned alongside a river system. ........................................................................................ 59
Figure 15. Example 2: Map indicating the edge of the supratidal zone, estuary boundary (5 m
AMSL), recommended aquatic impact buffer zone and final recommended setback requirement for
a proposed residential development planned alongside an estuarine system. .................................... 59

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ABBREVIATIONS USED IN THIS REPORT
AMD Acid Mine Drainage
AMSL Above Mean Sea Level
ARD Acid Rock Drainage
BMP Best Management Practice
CRS Climate Risk Score
DO Dissolved Oxygen
DWA Department of Water Affairs
DWAF Department of Water Affairs and Forestry
EC Ecological Category
EI Economic Importance
EIA Environmental Impact Assessment
EIS Ecological Importance and Sensitivity
EMC Event Mean Concentration
EMF Environmental Management Framework
EPA Estuarine Protected Area
FBZ Forest Buffer Zone
GBZ Grassland Buffer Zone
GIS Geographic Information System
GLV General wastewater Limit Value
HGM Hydro-geomorphic
ISO International Organization for Standardization
MAP Mean Annual Precipitation
NBA National Biodiversity Assessment
NEC Nested Ecological Categories
NEMA National Environmental Management Act
NFEPA National Freshwater Ecosystem Priority Area
NWA National water Act
PES Present Ecological State
RDM Resource Directed Measures
REC Recommended Ecological Class
RQO Resource Quality Objective
SANBI South African Biodiversity Institute
SCS-SA Soil Conservation Services method for Southern Africa
SFR Surface Flow Requirement
SI Social Importance
SLV Special wastewater Limit Value
TOPS Threatened or Protected Species
WRC Water Research Commission
WRCS Water Resource Classification System

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Preliminary Guideline for the Determination of Buffer Zones 2014
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1. INTRODUCTION
1.1. Purpose of this report
This report is the twelfth and penultimate deliverable in the Water Research Commission project
K5/2200. The purpose of this draft report is to share the proposed method for determining
appropriate buffer zones for developments associated with wetlands, rivers and estuaries with the
reference group, technical peers and potential implementing agencies. The report will inform the
final report, which will be a ‘Beta version’ of a guideline document for users to determine appropriate
buffer zones for developments associated with wetlands, rivers and estuaries.
It is important to note that two deliverables, which may be of interest, have not been incorporated
into this report. These include:
• Deliverable 1: Literature review (Annexure 1); and
• Deliverable 11: Practical testing / field testing report (Annexure 2).
In addition to this report, which provides the concepts, background, and approach required to
determine appropriate buffer zones. It does however need to be used in conjunction with the buffer
zone tools developed for wetlands, rivers and estuaries, namely:
• Buffer zone tool for the determination of aquatic impact buffers and additional setback
requirements for wetland ecosystems (Macfarlane et al., 2014a);
• Buffer zone tool for the determination of aquatic impact buffers and additional setback
requirements for river ecosystems (Macfarlane et al., 2014b); and
• Buffer zone tool for the determination of aquatic impact buffers and additional setback
requirements for estuarine (Macfarlane et al., 2014c).
It is envisaged that the buffer tools developed will be the primary products from this project, and that
users will user the final report as a guideline document to enhance the use of the tools developed.
For this reason, a CD with the ‘Buffer Zone Tools’, additional deliverables of interest, the mitigation
measures tool, and data that will be helpful for the buffer zone determining process, has been
included as an attachment to the guideline document.
1.2. What are buffer zones?
Definitions of buffer zones are variable, depending on their purpose. Buffer zones have been used
in land-use planning to protect natural resources and limit the impact of one land-use on another.
This project specifically looks at aquatic buffer zones which are typically designed to act as a barrier
between human activities and sensitive water resources thereby protecting them from negative
impacts. The importance of other functions, particularly the provision of habitat necessary for
wetland-dependant species that require both aquatic and terrestrial habitats is also catered for when
establishing final setback requirements. For the purposes of this project, a working definition for
buffer zones has been defined below:
Buffer zone: A strip of land with a use, function or zoning specifically designed to
protect one area of land against impacts from another.

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1.3. Why are buffer zones regarded as important?
Buffer zones associated with water resources have been shown to perform a wide range of
functions, and on this basis, have been proposed as a standard measure to protect water resources
and associated biodiversity. These functions include:
(i) Maintaining basic aquatic processes;
(ii) Reducing impacts on water resources from upstream activities and adjoining land uses;
(iii) Providing habitat for aquatic and semi-aquatic species;
(iv) Providing habitat for terrestrial species; and
(v) A range of ancillary societal benefits
A brief description of each of the functions and associated services is outlined in Table 1.
Table 1. Summary of roles and associated functions provided by buffer zones
PRIMARY
ROLE BUFFER FUNCTIONS
Maintaining
basic aquatic
processes,
services and
values.
• Maintaining channel stability: Riparian vegetation, in particular, root systems,
strengthens stream banks while groundcover increases resistance to erosion,
improving channel stability and reducing the impacts on aquatic systems and
downstream users. Stream bank stability is particularly important during flood events,
with the amount of erosion being greatly reduced by good vegetation cover along
stream banks. Buffer zones can also prevent direct access of livestock to a waterway,
which prevents hoof-damage to stream banks and direct input of nutrients, organic
matter and pathogens in dung and urine.
• Control of microclimate and water temperature: Riparian vegetation may affect the
microclimate of the stream area nearest the stream bank and reduce water
temperatures. This can have serious consequences for aquatic biota as water
temperature plays a key role in the lifecycles of many species. The occurrence of
riparian vegetation also has a significant effect on aquatic plant growth, as light
incidence is the main variable controlling productivity in shaded streams. Removing
stream bank vegetation is likely to increase stream primary productivity, increase the
risk of eutrophication and change the species structure and community composition in
the water body. The lower temperatures caused by shading, also has important
consequences for other water quality variables besides temperature, such as the
dissolved oxygen concentration (DO), which increases with lower temperatures.
• Flood attenuation: Well-developed riparian vegetation increases the roughness of
stream margins, slowing down flood-flows. This may therefore reduce flood damage in
downstream areas. Aquatic buffers are therefore a cost-effective alternative to
engineered structures to reduce erosion and control flooding, particularly in urban
settings.
• Maintenance of general wildlife habitat: Riparian zones typically have intrinsically
high biodiversity value due to their structural diversity and location at an interface
between aquatic and terrestrial systems.
Reducing
impacts from
upstream
activities and
adjoining land
uses
• Storm water attenuation: Flooding into the buffer zone increases the area and
reduces the velocity of storm flow. Roots, branches and leaves of plants provide direct
resistance to water flowing through the buffer, decreasing its velocity and thereby
reducing its erosion potential.
• Sediment removal: Surface roughness provided by vegetation, or litter, reduces the
velocity of overland flow, enhancing settling of particles. Buffer zones can therefore act
as effective sediment traps, removing sediment from runoff water from adjoining lands

Preliminary Guideline for the Determination of Buffer Zones 2014
3
PRIMARY
ROLE BUFFER FUNCTIONS
thus reducing the sediment load of surface waters.
• Removal of toxics: Buffer zones can remove toxic pollutants, such pesticides, metals
and other chemicals that would otherwise affect the quality of water resources and thus
their suitability for aquatic biota and for human use.
• Nutrient removal: Riparian vegetation and vegetation in terrestrial buffer zones may
significantly reduce the amount of nutrients (N & P), entering a water body reducing the
potential for excessive outbreaks of microalgae that can have an adverse effect on
both freshwater and estuarine environments.
• Removal of pathogens: By slowing water contaminated with faeces, buffer zones
encourage deposition of pathogens, which soon die when exposed to the elements.
Meeting life-
need
requirements
for aquatic and
semi-aquatic
species
• Provision of habitat for aquatic species: Riparian vegetation along stream lines
provides food that supports in stream food chains while branches and trees that fall
into the stream also provide vital habitat for certain species of aquatic fauna. Provision
of habitat for semi-aquatic species: Many semi-aquatic species rely on terrestrial
habitats for the successful recruitment of juveniles and to maintain optimal adult
survival rates.
• Screening of adjacent disturbances: Anthropogenic disturbances to aquatic and
semi-aquatic species may be direct, such as human presence and traffic or indirect,
such as through noise and light. These disrupt natural wildlife activities, such as
feeding, breeding and sleeping, or may affect habitat quality, adversely affecting their
survival.
• Habitat connectivity: Buffers along water resources provide potentially useful
corridors, allowing the connection of breeding, feeding and refuge sites crucial to
maintain the viability of populations of semi-aquatic species.
Providing
habitat for
terrestrial
species
• Provision of habitat for terrestrial species: In certain situations, buffers established
alongside water resources may be critical for the persistence of terrestrial species.
This is particularly likely in highly developed landscapes where undeveloped buffers
may provide the only remaining terrestrial habitat.
• Habitat connectivity: Buffers along water resources provide potentially useful
corridors, allowing the connection of breeding, feeding and refuge sites crucial to
maintain the viability of populations of terrestrial species
Ancillary
societal
benefits
• Reduces flood risk: Through increased resistance to flow, riparian areas and buffer
zones can increase residence time of floodwaters, reducing flow velocities and thereby
reducing flood peaks. This can reduce safety risks to people and property in the
downstream catchment.
• Enhances visual quality: Buffer zones can enhance visual interest and screen
undesirable views, thereby enhancing visual quality, particularly in urban areas.
• Control noise levels: Wooded buffer zones can reduce noise from roads and other
sources to levels that allow normal outdoor activities to occur.
• Improve air quality: Vegetation in buffer zones can affect local and regional air
quality by reducing temperature and removing air pollutants.
• Provides recreational opportunities: The availability of open space associated with
buffer zones provides opportunities for a range of recreational activities. This is
particularly important in urban areas where availability of open space areas is often
lacking.
• Economic benefits: The proximity of residential areas to well managed buffer zones
can lead to increased property values due to perceived aesthetic, recreational and
other benefits. Such areas may also provide opportunities for tourism activities and
provide a sustainable supply of natural resources for local communities.

Preliminary Guideline for the Determination of Buffer Zones 2014
4
1.4. What buffers don’t do
Despite the range of functions potentially provided by buffer zones, buffer zones are far from a
“silver bullet” that addresses all water resource related problems. Indeed, buffers can do little
to address some impacts such as hydrological changes caused by stream flow reduction activities
or changes in flow brought about by abstractions or upstream impoundments. Buffer zones are also
not the appropriate tool for militating against point-source discharges (e.g. sewage outflows), which
can be more effectively managed by targeting these areas through specific source-directed controls.
Contamination or use of groundwater is also not well addressed by buffer zones and requires
complementary approaches such as controlling activities in sensitive groundwater zones. The role
that buffers can play must therefore be well understood when applying these guidelines. For an
overview of typical threats posed to water resources and the role that buffers and other
management measures can play in addressing these concerns, please see Annexure 3.
Despite clear limitations, buffer zones are well suited to perform functions such as sediment
trapping and nutrient retention which can significantly reduce the impact of activities taking place
adjacent to water resources. Buffer zones are therefore proposed as a standard mitigation
measure to reduce impacts of land uses / activities planned adjacent to water resources.
These must however be considered in conjunction with other mitigation measures which may be
required to address specific impacts for which buffer zones are not well suited to address.
2. CONCEPTUAL FRAMEWORK FOR DEVELOPING A BUFFER ZONE
METHOD
In developing an approach for buffer zone determination, a number of key decisions were made that
informed the development of the method presented in this report. The rationale and consequent
assumptions are presented below.
2.1. Design criteria used to inform the development of a method
and model for buffer determination
Based on the review of generic approaches and specific methodologies, a broad set of design
criteria to guide the development of an appropriate approach were developed. These criteria are
listed below and set the goals that were used to inform the design of a conceptual framework and
method for buffer zone determination in the South African context.
Levels of expertise: As far as possible, the method should be easy and quick to apply by
personnel with little training or experience in ecology or water resource management. Any approach
must however recognize that a greater level of expertise may be necessary to inform some detailed
assessments where there is a high risk factor or where there are potentially significant impacts
associated with the proposed development at a particular site.
Precautionary principle: Where information is lacking or little information is available to inform the
establishment of a buffer zone, a cautious approach is recommended, one that recognizes the
potential shortfalls and inaccuracies of the assessment. In situations where good information is
available however and where buffer zone widths are informed by a sound understanding of
requirements, a less conservative approach should be followed. This is consistent with the
precautionary principle set out in the National Environmental Management Act (NEMA) which

Preliminary Guideline for the Determination of Buffer Zones 2014
5
recommends following a risk-averse, cautious approach that takes into account the limits of current
knowledge about the consequences of decisions and actions.
Predictability and administration: A level of predictability in model outcomes is preferred across
different levels of assessment. It is however recognized that buffer widths may need to be refined
for site-based assessments where additional information is available to inform buffer determination.
The need for clear guidelines is also recognized to ensure that the method can be applied
consistently by a range of users.
Data collection and assessment: Buffer width determination should rely as far as possible on
existing information or information collected during current aquatic assessments to ensure that
additional expenditure necessary to inform buffer determination is kept to a minimum. The
approach should therefore make use of existing methods of assessment as far as possible.
Collection of detailed site-specific information should also be the exception rather than the rule. It is
however recognized that it may be necessary to tailor the level of data collection according to the
levels of assessment being undertaken (regional planning through to site-level).
Buffer widths should be tailored according to risk: This criterion recognizes the importance of
using risk as a basis for establishing an appropriate buffer width. Where risk or uncertainty is high,
ecologically conservative buffers should be established whereas less conservative buffers are
appropriate for low-risk situations. A number of key risk factors have been identified for possible
inclusion in the approach. These include:
(i) Risks posed by adjacent land uses or activities;
(ii) The importance and sensitivity of the water resource;
(iii) The conservation status (risk of extinction) of aquatic and semi-aquatic species;
(iv) Characteristics of the buffer that affects the functionality of the buffer; and
(v) Mitigation measures that may be applied to reduce risks.
2.2. Selection of an appropriate approach for setting buffers
The literature review revealed that international approaches used to determine required buffer zone
widths varied considerably from simple one-size fits all approaches to others that rely on extensive
site-specific information to inform buffer width requirements. Three generic approaches were
identified in the literature, and are briefly outlined below:
• Fixed-width: The fixed width approach typically applies a standard buffer width to a particular
water resource type. In some instances, a generic width is applied regardless of any
characteristic of the water resource. However, this approach is more typically applied to a class
of wetland or river type or a specific land use type / activity.
• Modified fixed-width: In this approach, a matrix of factors is typically used to categorize
wetlands and / land uses with category specific standard buffer widths being applied to the
resource. These widths may however be modified based on relevant on-site factors where more
detailed information is available.
• Variable width: This approach usually requires the development of a detailed formula and
methodology for considering site-specific factors such as wetland type, adjacent land use,

Preliminary Guideline for the Determination of Buffer Zones 2014
6
vegetation, soils, wildlife habitats, slope, desired function and other special site-specific
characteristics to calculate buffer widths.
While each approach has a number of advantages and disadvantages, the modified fixed-width
approach was regarded as most appropriate for the South African context. This was principally due
to the need to develop a tool that could be applied across different levels (i.e. desktop and site-
based), while maintaining a level of predictability and consistency between approaches. The
method outlined in this document therefore proposes highly conservative buffer widths based on
generic relationships for broad-scale assessments but allows these to be modified based on more
detailed site-level information. Resultant buffers therefore range from highly conservative, fixed
widths for different land uses at a desktop level to buffers that are modified based on a more
thorough understanding of the water resource and specific site characteristics.
2.3. Designing an approach to cater for the full range of buffer
functions
As discussed previously, buffer zones established around water resources perform a wide range of
roles and functions. The importance of each of these roles is likely to be case-dependent, and as
such, the approach needs to be flexible to allow buffers to be tailored according to site-specific
requirements. It is important to note however that this guideline is not designed to address all these
roles and functions, and is focused specifically on protecting water resources and associated biota.
The approach adopted as part of this guideline has therefore been developed to ensure that
relevant functions are adequately addressed. This includes:
• Maintaining basic aquatic processes, services and values: As a minimum, this requires the
maintenance of the water resource, including any riparian habitat. Delineation and protection of
water resources, as defined in South African legislation, including riparian habitat is therefore
regarded as mandatory to ensure no direct impacts to these areas. The method developed is
therefore designed to ensure that such areas are identified and mapped and included within any
recommended setback area. The need for additional management measures, including
potential additional management buffers to safeguard intact riparian habitat is also addressed.
• Reducing impacts from adjacent land use activities: This requires an understanding of
specific risks associated with planned land uses / activities and the degree to which buffer zones
can address these impacts. Aquatic impact buffers are therefore only proposed where
appropriate, based on an understanding of specific risks and the ability of buffer zones to
address potential impacts.
• Meeting life-need requirements for aquatic and semi-aquatic species: Although there is an
apparent widespread application of buffers for biodiversity protection in the international
literature, it is regarded as an overly simplistic approach for biodiversity protection. What is
required, however, is an appropriate understanding of specific species habitat and protection
requirements to safeguard important species present. This method has therefore been
designed to guide the identification of important biodiversity elements and to help ensure that
appropriate steps are taken to adequately cater for the protection of important species and
habitats. This moves beyond the simple concept of buffer zones and considers aspects such as
core area requirements, connectivity and management.

Preliminary Guideline for the Determination of Buffer Zones 2014
7
Functions not specifically addressed as part of this guideline include reducing the impacts from
upstream activities; the provision of habitat for terrestrial species and ancillary societal benefits.
Suggestions as to how these considerations can be included in an assessment are however
provided below:
• Reducing impacts from upstream activities: Whilst buffer zones are not designed to
specifically address impacts associated with upstream activities the establishment of buffer
zones (including riparian habitat) will help to ensure that these functions (e.g. stormwater
attenuation and water quality enhancement) are retained. Managing catchment-level impacts
should however be addressed through catchment management activities.
• Providing habitat for terrestrial species: Local protection requirements, including buffer zone
establishment may well be supported further by conservation objectives for terrestrial habitat
and species which make use of habitat within delineated buffer zones. This requires an
understanding of the conservation value of terrestrial ecosystems and the ecology of any
terrestrial species of conservation concern.
• Ancillary societal benefits: In many instances, societal benefits can be addressed through
design and management of buffer zones. This links to building an understanding of the
importance of the resource in more than ecological terms and setting appropriate management
objectives. Where societal benefits are particularly important, such as protecting people and
property from flood risks, buffer zones may need to be enlarged to cater for these requirements
(e.g. by limiting development within flood zones). In other situations, manipulation of species
composition and structure may add significantly to societal benefits without compromising
desired ecological outcomes.
2.4. Developing an approach in the absence of a formally
structured assessment framework
At the time of developing this guideline, there was no formalized structured framework to guide
water resource protection and assessment processes. The legislation supporting implementation of
buffer zones, though present, is also fragmented and provides little guidance as to when and how
this buffer zone guideline should be applied. Without a legal and assessment framework, there is a
legitimate concern that these buffer zone guidelines may be advocated or applied without due
consideration of the full suite of potential impacts associated with developments and other tools
available for water resource protection.
In response to this concern, we have expanded the scope of this guideline in a number of ways.
This includes:
• Contextualizing the use and applicability of buffer zones within a broader suite of
management measures to protect water resources;
• Including objective setting as a separate step in the model to ensure that decision-making is
informed my sound information, with specific outcomes in mind;
• Broadening the risk assessment framework to cater for a broad suite of potential diffuse
source impacts, rather than simply focusing on those that buffer zones are known to help
address;

Preliminary Guideline for the Determination of Buffer Zones 2014
8
• Identifying a suite of additional mitigation measures that can be used to address diffuse
source impacts.
3. THE ASSESSMENT PROCEDURE
The assessment procedure has been structured in an 8 Step process as outlined in Figure 1 below.
This provides a broad overview of the process, but is expanded with considerable detail in the text
that follows. Explicit instructions are also provided for populating the Excel model used to determine
buffer zone requirements.

Preliminary Guideline for the Determination of Buffer Zones 2014
9
Figure 1. Overview of the step-wise assessment process
STEP 1: DEFINE OBJECTIVES
AND SCOPE TO DETERMINE THE
MOST APPROPRIATE LEVEL OF
ASSESSMENT
STEP 2: MAP AND CATEGORIZE WATER
RESOURCES IN THE STUDY AREA
STEP 3: REFER TO THE DWA
MANAGEMENT OBJECTIVES FOR
MAPPED WATER RESOURCES OR
DEVELOP SURROGATE OBJECTIVES
STEP 4: ASSESS THE RISKS FROM PROPOSED
DEVELOPMENTS AND DEFINE MITIGATION
MEASURES NECESSARY TO PROTECT MAPPED
WATER RESOURCES IN THE STUDY AREA
STEP 5: ASSESS RISKS POSED BY
PROPOSED DEVELOPMENT ON
BIODIVERSITY AND IDENTIFY
MANAGEMENT ZONES FOR BIODIVERSITY
PROTECTION
STEP 6: DELINEATE AND DEMARCATE
RECOMMENDED SETBACK
REQUIREMENTS
STEP 7: DOCUMENT MANAGEMENT
MEASURES NECESSARY TO MAINTAIN
THE EFFECTIVENESS OF SETBACK
AREAS
STEP 8: MONITOR IMPLEMENTATION OF
BUFFER ZONES

Preliminary Guideline for the Determination of Buffer Zones 2014
10
4. STEP 1: DEFINE OBJECTIVES AND SCOPE TO DETERMINE THE
MOST APPROPRIATE LEVEL OF THE ASSESSMENT
4.1. Define objectives and scope of the assessment
The requirements for assessing potential impacts and establishing buffer zone requirements
may be very diverse. It is important therefore that before any assessment is undertaken, the
specific objective for undertaking the assessment is clearly understood. Some instances in
which the application of this procedure may be necessary and appropriate are outlined
below:
• Flagging areas with potential constraints to development as part of an Environmental
Management Framework assessment;
• Re-zoning an area from residential to industrial land use and identifying property-
specific limitations to developments within the rezoned areas;
• Assessing potential impacts and identifying appropriate mitigation measures as part
of an EIA application for a development proposed within 32 m of a wetland;
• Assessing impacts of section 21 (c) or (i) of the National Water Act (NWA), i.e.
assessing water use activities and identifying realistic and measurable mitigation
measures for these impacts;
• Complying with Resource Quality Objectives where establishment of buffer zones
have been recommended in line with management objectives for the water resource;
and
• Applying best-practice guidelines as part of an environmental certification scheme
aimed at minimizing or reducing potential environmental impacts (e.g. ISO 14001).
Although existing legislation makes provision for the application of these guidelines as
shown above, no specific regulations have been developed to enforce the use of this tool. It
is however envisaged that this guideline will be endorsed as a best-practice guideline by the
Department of Water Affairs and will therefore become entrenched in water resource
assessments.
It is also important to clarify the geographical boundaries of the assessment and to consider
the resources available to undertake the assessment, as this could affect the level of
assessment undertaken. In some instances, the assessment needs to be applied across a
large geographic area, covering numerous water resource types and potential activities. In
other situations, the approach is applied to assess the impacts of a specific development to
inform site-based decision-making.
4.2. Determine the most appropriate level of
assessment
Given the range of potential users and applications, a tiered approach for buffer zone
determination has been developed, which incorporates two levels of assessment:
• Desktop assessment: This assessment is designed to characterize risks at a
desktop level in order to red-flag land located adjacent to water resources that should
potentially be set aside and managed to limit impacts on water resources. Whilst a
Desktop Site-based
Y Y

Preliminary Guideline for the Determination of Buffer Zones 2014
11
precautionary approach is taken to calculating buffer requirements at this level, this
assessment should not be used as a basis for authorizing development or activities
with a potential impact on water resources as it does not cater for biodiversity
considerations or other site factors.
• Site-based assessment: This assessment is designed for site-based assessments
and includes a more detailed evaluation of risks and consideration of site-specific
factors that can affect buffer requirements. Such an approach is designed to inform
any detailed development planning and provide an appropriate level of information
for authorization purposes.
Buffer zone determination may be undertaken at either of these levels and should be
informed by (i) the intended purpose of buffer zone determination, (ii) the approach to be
followed, (iii) the level of expertise available to undertake the assessment and (iv) the time
and cost required to undertake the assessment. Table 2 provides a summary of the different
levels of assessment that should be used to inform the selection of an appropriate approach
based on the objectives of the assessment and resource constraints.
Table 2. Summary of the different levels of assessment for buffer zone determination
Level of
assessment Desktop Site-based
Purpose
Identify areas of potential development
constraints associated with water
resources at a municipal or catchment
scale to inform development planning.
Priority users: National, Provincial, and
Municipal planners, owners, developers
Establish buffer zone requirements to
inform detailed development planning at
a site level.
Priority users: Developers, EIA
consultants
Approach
followed
Buffer zones are determined by
accounting for generic risks associated
with different land use sectors. A
precautionary approach is followed by
calculating buffer requirements based on
a “worst-case” scenario. The model also
takes basic climatic factors into account.
Buffer zone requirements are based on
detailed site information. This includes
local climatic conditions; risks associated
with the specific land use activity; the
sensitivity of the receiving environment
and local buffer attributes. Specific
consideration is also given to the
maintenance of biodiversity attributes.
Level of
expertise Suitably qualified assessor
Specialist aquatic ecologist. May need
to supplement with further studies from a
biodiversity specialist if important biota
are present.
Time and
cost Rapid desktop assessment, with very
low cost implications
Comprehensive site assessment, with
moderate cost implications. Costs will
increase if a biodiversity assessment is
required.
Depending on the particular requirements, the appropriate level of assessment should be
chosen. This is then documented in the appropriate buffer zone tool (separate tools have
been created for wetlands, rivers and estuaries) which directs users to further data capture
requirements. To help guide users through the document, a simple tab has also been
included at the start of each step to indicate whether or not the step is relevant for the level
of assessment being undertaken. Where not required, the assessor can simply move onto

Preliminary Guideline for the Determination of Buffer Zones 2014
12
the next step. The same colour scheme is included in the model to help guide the assessor
through the process.
Buffer zone tool:
• Select the appropriate Excel tool based on the type of water resource under
investigation (wetland, river or estuary)
• Select the appropriate level of assessment from the drop-down list provided.
5. STEP 2: MAP AND CATEGORIZE WATER RESOURCES IN THE
STUDY AREA
5.1. Map water resource boundaries
After establishing the scope and appropriate level of the
assessment, the assessor is required to generate a map delineating the boundaries of the
water resources potentially affected by proposed developments within the study area1. A
Geographic Information System (GIS) is particularly useful during the mapping process,
since it can be used to provide very useful spatial information to inform the assessment,
especially where buffers need to be applied across a broad spatial scale. Where these
facilities are not available, orthophotos (1:10 000) or Google Earth maps may be used to
inform site assessments.
To ensure that mapping is undertaken in a consistent manner, water resources have been
defined according to current South African legal definitions and best available science.
Definitions for relevant water resource types 2 and associated elements are briefly described
below:
• Estuary: In line with the National Wetland Classification System (SANBI, 2009) and in
terms of the recently enacted Integrated Coastal Management Act (Act No. 24 of 2008),
an estuary is defined as “a body of surface water – (a) that is part of a water course
that is permanently or periodically open to the sea; (b) in which a rise and fall of
the water level as a result of the tides is measurable at spring tides when the water
course is open to the sea; or (c) in respect of which the salinity is measurably
higher as a result of the influence of the sea” 3
. This is in line with the following
definitions for the boundaries of an estuary contained in the Resource Directed
Measures (RDM) Manual for Estuaries (DWAF 2008):
1 Where an application for a water use license is being applied for, all wetlands within 500 m of the proposed
development should ideally be mapped.
2 According to the definitions in the National Water Act (Act No. 36 of 1998), “water resource'' includes a
watercourse, surface water, estuary, or aquifer.
3 Historically, Estuarine Systems, which are no longer connected to the sea (i.e. they are permanently closed)
but often retain the saline character and much of the fauna associated with estuaries, such as many of the
“coastal lakes” in South Africa, are not considered to be Estuarine Systems. These aquatic ecosystems are,
rather, considered to be Inland Systems because they do not have an existing permanent or periodic
connection to the sea.
Desktop Site-based
Y Y

Preliminary Guideline for the Determination of Buffer Zones 2014
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• Downstream boundary: The estuary mouth, or where the mouth is closed, the
middle of the sand berm between the open water and the sea.
• Upstream boundary: The extent of tidal influence (i.e. the point up to where tidal
variation in water levels can still be detected), or the extent of saline intrusion, or the
extent of back-flooding during the closed mouth state, whichever is furthest
upstream.
• Lateral boundaries: The 5 m Above Mean Sea Level (AMSL) contour along each
bank.
From consultations during the development of a National Wetland Classification
System (SANBI, 2009), the above-mentioned definitions are regarded as more
appropriate than that contained in the National Water Act (Act No. 36 of 1998), which
is based on the more dated definition, whereby saline intrusion was the sole criterion
for determining the upstream boundary of an estuary4.
• Rivers and streams: This type of water resource is described as a Channel (river,
including the banks) in the National Wetland Classification System (SANBI, 2009). This
is defined as “an open conduit with clearly defined margins that (i) continuously or
periodically contains flowing water, or (ii) forms a connecting link between two
water bodies. Dominant water sources include concentrated surface flow from
upstream channels and tributaries, diffuse surface flow or interflow, and/or
groundwater flow. Water moves through the system as concentrated flow and
usually exits as such but can exit as diffuse surface flow because of a sudden
change in gradient. Unidirectional channel-contained horizontal flow
characterises the hydrodynamic nature of these units.” According to the
classification system, channels generally refer to rivers or streams (including those that
have been canalised) that are subject to concentrated flow on a continuous basis or
periodically during flooding. This definition is consistent with the National Water Act (Act
No. 36 of 1998) which makes reference to (i) a river or spring and (ii) a natural channel in
which water flows regularly or intermittently within the definition of a water resource. As
a result of the erosive forces associated with concentrated flow, channels
characteristically have relatively obvious active channel5 banks which can be identified
and delineated.
• Wetland: This means “land which is transitional between a terrestrial and aquatic
system where the water table is usually at or near the surface or the land is periodically
4 According to the National Water Act, an estuary is defined as “a partially or fully enclosed water body – (a)
that is open to the sea permanently or periodically; and (b) within which the seawater can be diluted, to an
extent that is measurable, with freshwater drained from land”.
5 According to the National Wetland Classification System (SANBI, 2009), active channel is defined as “a
channel that is inundated at sufficiently regular intervals to maintain channel form and keep the channel free
of established terrestrial vegetation. These channels are typically filled to capacity during bank full discharge
(i.e. during the annual flood, except for intermittent rivers that do not flood annually). [NOTE: Mid-channel bars
(associated with braided river systems) and side bars (associated with meandering river systems) are
unvegetated, transient features that are considered to be part of the active channel.]”. A useful description
and illustration of the differences between the active channel and riparian zone of a river are included in Box 7
of the user manual for the classification system for wetlands and other aquatic ecosystems in South Africa
(Ollis, et. al. 2013).

Preliminary Guideline for the Determination of Buffer Zones 2014
14
covered with shallow water, and which land in normal circumstances supports or would
support vegetation typically adapted to life in saturated soil.”
It is important to note that “Riparian habitat” may be associated with either of these systems
and is regarded by DWA as part of the water resource and “regulated area”. Riparian
habitat is defined in the National Water Act (Act No. 36 of 1998) as “the physical structure
and associated vegetation of the areas associated with a watercourse which are
commonly characterised by alluvial soils, and which are inundated or flooded to an
extent and with a frequency sufficient to support vegetation of species with a
composition and physical structure distinct from those of adjacent land areas.” Areas
of riparian habitat which are saturated or flooded for prolonged periods would be considered
‘wetlands’ (in terms of both the NWA) and should be mapped as such. Some riparian areas,
however, are not ‘wetlands’ (e.g. where characteristic riparian trees have very deep roots
drawing water from many metres below the surface). These areas do however provide a
range of important services that maintain basic aquatic processes, services and values
requiring protection in their own right. Where present, the boundary of the riparian habitat
should therefore also be clearly delineated. Examples of riparian zone habitat associated
with two different river systems are indicated in Photos 1 & 2, below.
Photo 1. Narrow riparian zone dominated by
grasses and small shrubs along stream line in
the KZN Midlands.
Photo 2. Large trees occupying a broader
riparian zone along a river in the lowveld of
Mpumalanga.
Mapping requirements are tailored according to the level of assessment being undertaken.
For the desktop assessment, water resources are mapped using available, often low
resolution data. Where site-based assessments are required, accurate mapping of water
resources is an essential first step in the assessment process. Guidelines for minimum
mapping requirements for different levels of assessment are detailed in Table 3 below. It is
important to note however that although minimum mapping requirements are indicated here,
use should be made of the best available information for the area under investigation. The
approach used to delineate the water resource should then be captured in the supporting
buffer
Photo: Doug Macfarlane Photo: Doug Macfarlane

Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 3. Minimum requirements for mapping the boundaries of water resources.
LEVEL OF
ASSESSMENT BOUNDARY
LINE MINIMUM MAPPING REQUIRED
Estuaries
Desktop
5 m AMSL line
Use 5 m AMSL line available for 299 estuarine systems
along the South African coastline (CSIR. National Estuaries
GIS dataset [National estuaries_12_2012] 2012. Available
from Biodiversity GIS website (http://bgis.sanbi.org).
Site-based 5 m AMSL line verified and refined based on more detailed
topographical information if available.
Rivers
Desktop Edge of
riparian habitat
Estimate of riparian zone width based on maximum of 1:100
flood line or relevant alluvial vegetation types included in the
Vegetation map of South Africa (Mucina & Rutherford,
2006). Where available, aerial photography can be used to
more accurately map riparian areas at a desktop level.
Site-based Site-based delineation of riparian zone based on DWAF
delineation manual (DWAF, 2008).
Wetlands
Desktop Edge of
temporary
zone
Wetlands included in the National Freshwater Ecosystems
Priority Areas Map which includes the latest wetland
classification layer – National Wetlands Map 4 (CSIR.
NFEPA Wetlands / National Wetlands Map
[NFEPA_wetlands]. Available from Biodiversity GIS website
(http://bgis.sanbi.org). Where available, wetlands mapped at
a finer catchment scale (c.a. 1:10 000) or at a desktop level
from aerial photography should be used.
Site-based Site-based delineation of wetland boundary based on DWAF
delineation manual (DWAF, 2008)
5.2. Map the line from which aquatic
impact buffer zones will be delineated
Whilst the edge of the water resource (described above) must be accurately delineated, the
starting point used for delineating aquatic impact buffer zones in this approach varies
according to the water resource type under consideration:
• Rivers and streams – the outer edge of the active channel;
• Wetlands
– the edge of the temporary zone (water resource boundary); and
• Estuaries
– the upper edge of the supratidal zone.
Due to their positioning adjacent to water bodies, buffer zones associated with streams and
rivers will typically incorporate riparian habitat, which (as defined by the National Water Act)
includes the physical structure and associated vegetation of the areas associated with a
watercourse which are commonly characterised by alluvial soils (deposited by the current
river system), and which are inundated or flooded to an extent and with a frequency
sufficient to support vegetation of species with a composition and physical structure distinct
from those of adjacent land areas. The riparian zone is not the only vegetation type that lies
in the buffer zone however and it may also incorporate stream banks and terrestrial habitats
depending on the width of the aquatic impact buffer zone applied. A diagram indicating how
riparian habitat typically relates to aquatic buffer zones defined in this guideline is provided in
Figure 2. There may however be instances in which the riparian zone extends beyond the
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Preliminary Guideline for the Determination of Buffer Zones 2014
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aquatic impact buffer zone. In this instance, setback requirements include the full extent of
the riparian zone and any additional requirements that may apply to managing this area.
Figure 2. Schematic diagram indicating the boundary of active channel and riparian
habitat and the areas potentially included in an aquatic impact buffer zone.
In the case of estuaries, a zone of terrestrial habitat is typically included within the delineated
water resource boundary. To be consistent with other water resource types, the aquatic
impact buffer zone should therefore be measured from a comparative point. This is taken as
the upper edge of the supratidal zone, defined as the area that is periodically inundated by
tidal or flood waters and within which the sub-surface water is saline and is generally
between 2.0 and 3.5 m AMSL (SANBI, 2009).
The starting line from which the aquatic impact buffer zone is determined must be delineated
through an appropriate approach, depending on the level of assessment being undertaken
(Table 4).
Table 4. Minimum requirements for mapping the line from which aquatic impact buffers will
be determined.
LEVEL OF
ASSESSMENT BOUNDARY
LINE MINIMUM MAPPING REQUIRED
Estuaries
Desktop Upper edge of
the supratidal
zone
Use the broader boundary of either (i) the open water
boundary area available for 299 estuarine systems along the
South African coastline (CSIR, 2012. National Estuaries
GIS dataset. Available at: http://bgis.sanbi.org.) or (ii) SA
Vegetation Map (water bodies and estuarine vegetation).
Site-based Site-based delineation using GPS or delineation from 1:10
000 orthophotos or other available imagery.
Source: Doug Macfarlane

Preliminary Guideline for the Determination of Buffer Zones 2014
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LEVEL OF
ASSESSMENT BOUNDARY
LINE MINIMUM MAPPING REQUIRED
Rivers
Desktop Edge of active
channel
Use river lines and areas of open water areas obtained from
1:50 000 topo-cadastral maps.
Site-based Site-based delineation of active channel banks.
Wetlands
Desktop Edge of
temporary
zone
Wetlands included in the National Freshwater Ecosystems
Priority Areas Map which includes the latest wetland
classification layer – National Wetlands Map 4 (CSIR.
NFEPA Wetlands / National Wetlands Map
[NFEPA_wetlands]. Available from Biodiversity GIS website
(http://bgis.sanbi.org). Where available, wetlands mapped at
a finer catchment scale (c.a. 1:10 000) or at a desktop level
from aerial photography should be used.
Site-based Site-based delineation of wetland boundary based on DWAF
delineation manual (DWAF, 2008)
Note: It is important that these buffer zone guidelines do not apply to ephemeral drainage
features that lack active channel characteristics. As such, it is essential to differentiate
between a stream (albeit ephemeral) with a clear “active channel” and ephemeral drainage
features that lack such characteristics.
This differentiation should be based on the classification of river channels outlined in the
DWAF delineation guideline for wetlands and riparian areas (DWAF, 2005). The channel
network is divided into three types of channel, which are referred to as A Section, B Section,
or C Section channels as shown in Figure 3. The essential difference between the “A”, “B”
and “C” Sections is their position relative to the zone of saturation in the riparian area. Figure
3 shows two levels of the water table; the one marked “wet” depicts the highest level that the
water table would reach in a wet period when recharge of the zone of saturation has taken
place, while the one marked “dry” depicts the level of the water table at its lowest after a dry
period. The zone of saturation must be in contact with the channel network for base flow to
take place at any point in the channel and the classification separates the channel sections
that do not have base flow (A Sections) from those that sometimes have base flow (B
Sections) and those that always have base flow (C Sections).
A Sections are regarded as the least sensitive from a water yield and contaminant risk
perspective as they typically only carry water after storm events. As such, these buffer zone
guidelines do not apply to “A” Sections of rivers. It is nonetheless appropriate to take
practical measures to limit the risk of diffuse source pollutants entering such sections. This
could include the maintenance of a reduced vegetated buffer, based on expert opinion,
around such features.

Preliminary Guideline for the Determination of Buffer Zones 2014
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Figure 3. Classification of river channels (Adapted from DWAF, 2005)
5.3. Identify water resource type
Once water resources have been mapped, they should be fully
identified in line with the level of assessment being undertaken. Hydro-geomorphological
classification schemes exist to enable the full description and identification of wetlands,
estuaries and river types.
For the purposes of this assessment, the refined National Wetland Classification System for
South Africa is recommended (SANBI, 2009; Ollis et al., 2013). Classification requirements
for each level of assessment are as follows:
• Desktop assessment: Classification of each water resource to Level 3 (Sub-system
/ Landscape Unit).
• Site-based assessment: Classification of each water resource to Level 4
(Hydrogeomorphic unit).
A breakdown of the classification structure for each water resource type is provided in
Tables 5 to 7 below. For further details on the definitions of water resource types and for
guidance in applying the classification system, users are encouraged to obtain, from SANBI,
a copy of the classification document and associated user manuals.
Table 5. Proposed classification system for estuaries (SANBI, 2009)
LEVEL 2: REGIONAL
SETTING LEVEL 3: SUBSYSTEM LEVEL 4: HYDROGEOMORPHIC UNIT
BIOGEOGRAPHIC ZONES PERIODICITY OF
CONNECTION LANDFORM & HYDRODYNAMICS
Cool-temperate Zone
Warm-temperate Zone
Subtropical Zone
Permanently Open
Estuarine Bay
Estuarine Lake
Open Estuary
River Mouth
Temporarily Open/Closed Estuarine Lake
Closed Estuary
River Mouth
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Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 6. Proposed classification system for Rivers (adapted from SANBI, 2009 & Ollis et
al., 2013)
LEVEL 3: HGM TYPE LEVEL 4: HYDROGEOMORPHIC (HGM) UNIT
HGM TYPE LONGITUDINAL ZONATION / LANDFORM
A B
River
Mountain headwater stream
Mountain stream
Transitional
Upper foothill
Lower foothill
Lowland river
Rejuvenated bedrock fall
Rejuvenated foothill
Upland floodplain
Table 7. Proposed classification system for inland wetlands (adapted from SANBI, 2009 &
Ollis et al., 2013)
LEVEL 3: LANDSCAPE
UNIT LEVEL 4: HYDROGEOMORPHIC (HGM) UNIT
LANDSCAPE SETTING HGM TYPE LONGITUDINAL
ZONATION /
LANDFORM
DRAINAGE –
OUTFLOW
A B C
SLOPE
Seep [not applicable]
With channelled
outflow
Without channelled
outflow
Depression [not applicable]
Exorheic
Endorheic
Dammed
VALLEY FLOOR
Channelled valley-
bottom wetland
Valley-bottom
depression [not applicable]
Valley-bottom flat [not applicable]
Unchannelled valley-
bottom wetland
Valley-bottom
depression [not applicable]
Valley-bottom flat [not applicable]
Floodplain Floodplain depression [not applicable]
Floodplain flat [not applicable]
Depression [not applicable]
Exorheic
Endorheic
Dammed
Valley head seep [not applicable] [not applicable]
PLAIN
Floodplain wetland Floodplain depression [not applicable]
Floodplain flat [not applicable]
Unchannelled valley-
bottom wetland
Valley-bottom
depression [not applicable]
Valley-bottom flat [not applicable]
Depression [not applicable]
Exorheic
Endorheic
Wetland flat [not applicable] [not applicable]

Preliminary Guideline for the Determination of Buffer Zones 2014
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LEVEL 3: LANDSCAPE
UNIT LEVEL 4: HYDROGEOMORPHIC (HGM) UNIT
LANDSCAPE SETTING HGM TYPE LONGITUDINAL
ZONATION /
LANDFORM
DRAINAGE –
OUTFLOW
A B C
BENCH
(HILLTOP / SADDLE / Depression [not applicable]
SHELF) Exorheic
Endorheic
Wetland flat [not applicable] [not applicable]
Buffer zone tool:
• Clarify the approach used to delineate the water resources in the study together with the
water resource type based on drop-down lists provided.
6. STEP 3: REFER TO THE DWA MANAGEMENT OBJECTIVES FOR
MAPPED WATER RESOURCES OR DEVELOP SURROGATE
OBJECTIVES
Understanding the rationale and objective for resource protection is a key step in informing
protection requirements. It effectively provides the vision for water resource protection and
therefore sets the bar for water resource protection and rehabilitation. This step is routinely
carried out as part of the Resource Quality Objectives (RQO) approach aligned to the Water
Resource Classification of the resource, which is the responsibility of DWA.
Where neither the RQOs nor the reserve have been undertaken an investigation may be
required by the assessor to help set management objectives for the water resources under
consideration. These management objectives will not have the same validity as the DWA
RQOs because the process in this determination is necessarily less inclusive of
stakeholders.
Management objectives can also be informed by South Africa’s National Biodiversity
Assessment 2011 (Driver et al., 2011). The National Biodiversity Assessment (NBA) is
central to fulfilling SANBI’s mandate in terms of the National Environmental Management:
Biodiversity Act (Act 10 of 2004) to monitoring and reporting regularly on the state of
biodiversity in South Africa. The NBA provides an assessment of the current state of health
and protection for all types of ecosystems in South Africa.
The national-level biodiversity plan for South Africa’s estuaries can be used to set
management objectives. This plan prioritises estuaries and establishes which should be
assigned Estuarine Protected Area (EPA) status (Turpie et al., 2012). Annexure 4 lists the
national and regional priority estuaries, provides recommendations regarding the extent of
protection required for each, the recommended extent of the estuary perimeter that should
be free from development to an appropriate setback line of at least 500 m, and a provisional
estimate of the Recommended Ecological Category, or recommended future health class
determining the limitations of future water use, as required under the National Water Act.

Preliminary Guideline for the Determination of Buffer Zones 2014
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The level of reserve determination or classification required for a particular site is determined
by DWA based on a number of criteria, including:
• Type of proposed development (abstraction, instream dam, off channel dam, forestry,
etc.);
• Anticipated impact of the proposed development;
• Ecological importance and sensitivity of the water resource;
• Degree to which the catchment is already utilized;
• Regulated systems;
• Existing developments;
• Socio-economic importance.
In the absence of DWA providing appropriate guidance however (e.g. in the case of small
streams or wetlands), it may be necessary for provincial or local authorities to evaluate
development applications and determine the need for specialist investigations through a
similar screening process.
Once the appropriate level of assessment has been defined, it will guide the level of data
collection required in order to set the management objective for the water resource under
consideration. In the absence of classification, this requires an assessment of PES,
Ecological Importance and Sensitivity (EIS) and Social importance (SI).To do this, the
recommendation is to follow a process similar to the current accepted Reserve process to
define surrogate management objectives to inform the need for mitigation measures,
including aquatic buffer zones.
It is worth noting, however, that where impacts are likely to be low, it may be appropriate to
simply set a management objective to “Maintain” the status quo. This would ensure that
existing impacts are managed to a certain level without forcing applicants to undertake
extensive surveys to establish whether or not improvement in water resource quality is
required. This would also move away from an approach in which the environment may be
given precedence – by setting a management objective to “Improve” without giving any
consideration to the impacts that such a decision would have on current users of the water
resource.
6.1. Determine the Present Ecological State
(PES) and anticipated trajectory of water
resource change
The PES of a water resource reflects the change to the water resource from its reference
condition. In this regard, the reference condition of the water resource is interpreted as the
expected undisturbed or natural condition prior to anthropogenic change. The PES refers to
the current state or condition of the water course in terms of all its characteristics and
reflects the change to the water resource from its reference condition. This is expressed in
terms of its bio-physical components (characteristics) which include:
• Drivers (physico-chemical, geomorphology, hydrology) which provide a particular
habitat template; and
• Biological responses (e.g. fish, riparian vegetation, aquatic invertebrates, and
diatoms).
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Preliminary Guideline for the Determination of Buffer Zones 2014
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Ecological categories that can be defined for each of these components range from A to F –
A being the unmodified state and F being critically modified (Table 8). The scale represents
a continuum as illustrated below – the boundaries are notional (Figure 4).
Table 8. Generic ecological categories for Ecostatus components (modified from
Kleynhans, 1996 & Kleynhans, 1999)
ECOLOGICAL
CATEGORY DESCRIPTION SCORE
(% OF
TOTAL)
A Unmodified, natural. 90-100
B Largely natural with few modifications. A small change in natural
habitats and biota may have taken place but the ecosystem
functions are essentially unchanged. 80-89
C Moderately modified. Loss and change of natural habitat and biota
have occurred, but the basic ecosystem functions are still
predominantly unchanged. 60-79
D Largely modified. A large loss of natural habitat, biota and basic
ecosystem functions has occurred. 40-59
E Seriously modified. The loss of natural habitat, biota and basic
ecosystem functions is extensive. 20-39
F
Critically / Extremely modified. Modifications have reached a critical
level and the system has been modified completely with an almost
complete loss of natural habitat and biota. In the worst instances
the basic ecosystem functions have been destroyed and the
changes are irreversible.
0-19
Figure 4. Illustration of the distribution of Ecological Categories on a continuum
The so-called Ecostatus (integrated state) is regarded as the totality of the features and
characteristics of a water resource that affect its ability to support natural fauna and flora
(Table 9). The ability relates to the capacity of the system to provide a variety of goods and
services. The components selected to determine the Ecostatus are dependent on the water
resource type and the level of reserve required.
Table 9. Illustration of the summary of an EcoStatus assessment for a river system.
DRIVER COMPONENT COMPONENT EC
Hydrology E
Geomorphology E
Water Quality B/C
RESPONSE COMPONENTS COMPONENT EC
Fish C
Aquatic Invertebrates D
Instream C/D
Riparian Vegetation D
ECOSTATUS D
Desktop information of PES is available at various scales for different water resources
across the country and may be used to inform a desktop assessment. A range of tools have
been developed to determine the present state of different water resources and associated

Preliminary Guideline for the Determination of Buffer Zones 2014
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components at a site or reach level and should be applied as directed for the rapid or
detailed approach. Where a PES determination is required, guidance from DWA should be
obtained regarding the level of detail required to assess the PES. Relevant tools must then
be applied to assess PES and the associated EcoStatus.
Trajectory of change is relevant in that such information can be used to understand how the
current PES is likely to change and so help to understand what may be attainable as a future
management class. For example, a largely natural wetland (B Category) may be located in a
predominantly undeveloped catchment with a new development planned adjacent to this
water resource. Recent authorizations may however have been given to develop much of
the upper catchment to residential housing, which will substantially impact on the hydrology
of the system in the near future. Setting of a local management objective may therefore need
to reflect a lowered management category in light of anticipated future impacts.
A desktop assessment of present ecological status is available for all estuaries from the
National Biodiversity Assessment (van Niekerk & Turpie 2011). This status may need to be
checked for site-based buffer assessment studies. If any more recent ecological reserve
studies than that of van Niekerk & Turpie (2011) exists it should be examined to provide a
higher confidence of the present ecological status. There are a number of ongoing Water
Management Area classification studies which will also provide updates on present
ecological status for estuaries.
6.2. Determine the Importance and sensitivity
of the water resources
Obtaining an understanding of the importance and sensitivity of the
water resource, in ecological, social and economic terms helps to highlight functions that
need to be maintained or enhanced. Such information should be used to guide or influence
the decision on the level of protection required, which in turn determines the appropriate
management objective. Where importance is regarded as high, this may provide an
appropriate motivation to improve management of the water resource, while simply
maintaining the status quo may be acceptable where importance is moderate to low. In
order to determine the overall importance and sensitivity of a water resource, the ecological,
social and economic importance should be considered. Guidance as to how this assessment
should be undertaken is provided below.
6.2.1. Assessing Ecological Importance and Sensitivity
Ecological importance of a water resource is an expression of its importance to the
maintenance of ecological diversity and functioning on local and wider spatial scales.
Ecological sensitivity (or fragility) refers to the system’s ability to tolerate disturbance and its
capacity to recover from disturbance once it has occurred (resilience).
In the determination of EIS, the following ecological aspects are typically considered by an
ecological specialist as the basis for the estimation of ecological importance and sensitivity:
• The presence of rare and endangered species, unique species (i.e. endemic or
isolated populations) and communities, intolerant species and species diversity.
• Habitat diversity, including specific habitat types such as reaches with a high diversity
of habitat types, i.e. pools, riffles, runs, rapids, waterfalls, riparian forests, etc.
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Preliminary Guideline for the Determination of Buffer Zones 2014
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• The importance of the particular resource unit (e.g. river or reach of river) in providing
connectivity between different sections of the whole water resource, i.e. whether it
provides a migration route or corridor for species.
• The presence of conservation areas or relatively natural areas along the river
section.
• The sensitivity (or fragility) of the system and its resilience (i.e. the ability to recover
following disturbance) of the system to environmental changes is also considered.
Consideration of both the biotic and abiotic components is included here.
As with PES, desktop EIS scores are available for some resources and may be used to
obtain an indication of ecological importance in some instances (e.g. desktop assessments).
In most cases however, it is anticipated that site-specific information will need to be collected
to inform an assessment of the importance of the particular water resource under
consideration. DWA have developed a number of tools to assist in this process and should
be selected according to the level of assessment required and the type of water resource
being assessed. Table 10 provides a breakdown of the EIS categories typically applied.
Table 10. Generic EIS categories
EIS CATEGORY DESCRIPTION
Low / marginal Not ecologically important and sensitive at any scale. Biodiversity ubiquitous
and not sensitive to flow and habitat modifications (Wetlands: play an
insignificant role in moderating water quality and quantity)
Moderate Ecologically important and sensitive on provincial/local scale. Biodiversity not
usually sensitive to flow and habitat modifications. (Wetlands: play a small
role in moderating water quantity and quality)
High Ecologically important and sensitive and important. Biodiversity may be
sensitive to flow and habitat modifications. (Wetlands: Play a role in
moderating water quality and quantity)
Very High Ecologically important and sensitive on a national (or even international)
level. Biodiversity usually very sensitive to flow and habitat modifications.
(Wetlands: play a major role in moderating water quantity and quality).
An importance rating / index for all South Africa’s estuaries is available from Turpie and
Clark (2007). This represents the importance of an estuary to the maintenance of biological
and ecological diversity and functioning on a national scale. Importance of the estuary
together with the present ecological status is used to set the recommended ecological
category. The Estuary Importance Score takes size, the rarity of the estuary type within its
biographical zone, habitat and biodiversity of the estuary into account. Biodiversity
importance is based on the assessment of the importance of the estuary for plants,
invertebrates, fish and birds. All scores are presented on a scale of 0 (totally unimportant) to
100 (critically important) (Annexure 5).
6.2.2. Assessing Social Importance
Social importance can be assessed, by a social specialist within a similar framework as that
for ecological importance. Social Importance reflects the dependency of people on a healthy
functional water resource and how people value the resource. It considers the cultural and
tourism potential of the water resource.
Aspects included in the assessment of economic and social/cultural importance are typically:

Preliminary Guideline for the Determination of Buffer Zones 2014
25
• The extent to which people are dependent on the natural ecological functions of the
resource for water for basic human needs (sole source of supply),
• Dependence on the natural ecological functions of the water resource for subsistence
agriculture or aquaculture;
• Use of the water resource for recreation;
• The historical and archaeological value of the water resource;
• Its importance in rituals and rites of passage;
• Sacred or special places (e.g. where spirits live);
• The use of riparian plants (for building or traditional medicine), and
• The intrinsic and aesthetic value for those who live in the catchment, or who visit it.
Guidance for undertaking this assessment can be obtained from DWA, who are responsible
for developing appropriate tools for different water resources. Although some element of
subjectivity is inevitable in assessments such as these, the results are intended to be as
objective as possible and a reflection of the relative importance. They are not intended to be
subject to complex statistical analysis, nor to measure social values with precision, but to
capture a general feeling of the importance of different aspects of a water resource.
6.2.3. Assessing Economic Importance
In some circumstances, it may be appropriate to assess the economic importance of the
water resource. The economic value of a water resource is typically assessed in terms of
the net value generated by consumptive and non-consumptive use of the resource. Typical
indicators include the number and value of jobs generated by the use of the water, or the
amount of revenue generated
Water resources also provide other services which should be included in an economic
resource valuation where possible. These include the services and benefits provided by
aquatic ecosystems such as:
• Transport and/or purification of biodegradable wastes;
• Recreation and aesthetic opportunities;
• Food production;
• Flood attenuation and regulation; and
• Water-based transport.
Several tools to quantify the value of ecosystem services and benefits have been developed
and these should be used when assessing economic importance. Guidance for undertaking
this assessment should also be obtained from DWA, based on the level of detail required to
inform the assessment.
6.3. Determine the management objectives
for water resources
The process required for determining appropriate management objectives is dependent on
whether or not the Water Resource Classification System (WRCS) has been applied and
consequently if RQOs have been determined. Guidance for setting appropriate
management objectives with and without classification is described below.
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Preliminary Guideline for the Determination of Buffer Zones 2014
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6.3.1. With classification
Where the WRCS has been undertaken, and especially where RQOs have been set, then
both ecological and user requirements have been considered and a management class and
associated Nested Ecological Categories (NECs) have been agreed based on due
consideration of relevant management implications. In this case, the management objective
is determined simply by comparing the PES with the gazetted NEC for the water resource
being assessed using Table 11, below.
Table 11. Determining the management objective where the WRCS has been applied
NEC
A B C D
PES
A A
Maintain
B
Controlled
degradation
C
Controlled
degradation
D
Controlled
degradation
B A
Improve B
Maintain
C
Controlled
degradation
D
Controlled
degradation
C A
Improve B
Improve C
Maintain
D
Controlled
degradation
D A
Improve B
Improve C
Improve D
Maintain
<D A
Improve B
Improve C
Improve D
Improve
A description of possible management objectives is briefly described:
• Improve: Employ management measures with a view to improve the resource class.
• Maintain: Employ management measures with a view to maintain the resource class
as is.
• Controlled degradation: Employ management measures with a view to allowing
controlled degradation of the water resource.
It should also be noted that only classes A to D are acceptable ecological management
classes. Assessment categories E and F are not acceptable as future ecological
management classes, since they represent degrees of modification which have already
resulted in, or carry an unacceptably high risk of irreversible degradation of resource quality,
a condition which does not allow sustainable utilization of a water resource (MacKay, 1999).
6.3.2. Without classification
In the case of a desktop assessment, where information is not available and has not been
collected, the default objective should be set to “Maintain” the water resource in its present
state.
For site-based assessments, a Recommended Ecological Class (REC) and associated
management objective for the water resource is informed by an understanding of PES, EIS,
SI and EI where available. Trajectory of change should be considered here in selecting a
PES that is attainable rather than necessarily using the current PES, which may be subject
to rapid change in a high threat environment or to improvement through planned
rehabilitation interventions. The default table used to inform this process is detailed in Table
12 below but may be further informed through a process of formal consultation and
participation where a comprehensive determination is required.

Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 12. Determining the management objective based on PES and importance of the
water resource.
IMPORTANCE
Very high High Moderate Low
ATTAINABLE
PES
A A
Maintain
A
Maintain
A
Maintain
A
Maintain
B A
Improve
A/B
Improve
B
Maintain
B
Maintain
C B
Improve
B/C
Improve
C
Maintain
C
Maintain
D C
Improve
C/D
Improve
D
Maintain
D
Maintain
<D D
Improve
D
Improve
D
Improve
D
Improve
It should be noted that in the absence of classification, the precautionary principle is applied,
and the management objective for the water resource is based primarily on ecological
criteria. The management objective will thus be either to improve the ecological class or to
maintain the ecological class. No opportunity is provided to allow controlled degradation
under this scenario.
While this framework is useful in deciding on broad management objectives, it is very
simplistic and should ideally be adjusted based on an understanding of the rationale for
water resource protection. This encourages a move away from decision making dictated
purely by reference conditions and opens the door for creative thinking and objective-driven
decision making. This thinking is in line with recent ideas of Dufour & Piegay (2009),
described in the text box, below. The stated objective should therefore be appropriately
justified and used to inform how management and mitigation measures are selected and
described. In some cases, this may result in objectives that result in controlled degradation
but help to secure key values and services.
Buffer zone tool:
• Select the appropriate “PES” and “EIS” classes based on assessments undertaken
on the water resource from the drop-down list provided.
• Select the “Management Objective” for the water resource under consideration from
the drop-down list provided.
Rethinking restoration objectives (Dufour & Piegay, 2009)
A review of river restoration strategies argues that the aim of returning streams to a
reference state should be replaced by an objective-based approach where river
repair or improvement is valued in terms of the provision of ecosystem goods
and services, and where objectives are defined by reference to a broad array of
factors, including conservation, aesthetics, resource extraction, water quality,
heritage protection and flood management. The authors suggest that a major
challenge for future river restoration will be evaluating “naturalness” and showing how it
is profitable to human society.

Preliminary Guideline for the Determination of Buffer Zones 2014
28
7. STEP 4: ASSESS THE RISKS FROM PROPOSED
DEVELOPMENTS AND DEFINE MITIGATION MEASURES
NECESSARY TO PROTECT MAPPED WATER RESOURCES IN
THE STUDY AREA
As mentioned previously, it is important to note that this step has been expanded to include
a wide spectrum of risks posed by diffuse lateral surface inputs, to try and ensure that a wide
range of risks are evaluated and appropriately considered as part of a development
application. A range of potential impacts not well addressed by the establishment of buffer
zones, but with potentially significant impacts on water resources, have therefore been
included in this assessment.
It is important to note however that this assessment has been developed as a flagging tool
and has not been developed to replace comprehensive risk assessments or to assess the
significance of potential impacts to water resources. This is specifically relevant to mining
operations where risks are often substantial and are often linked with groundwater impacts
not addressed in this guideline. It is therefore important to note that the risk assessment
included in the buffer zone model specifically excludes risks associated with point-source
discharges and groundwater use and contamination.
7.1. Undertake a risk assessment to assess the potential
impacts of planned activities on water resources
The risk of a proposed activity on water resources is used as the primary driver for defining
the level of mitigation (including buffer zone width) required. In this context, a risk
assessment is a process of gathering data and making assumptions relating to the probable
effects on the environment based on the probability of an event occurring, the factors that
could bring about that event, likely exposure levels and the acceptability of the impact
resulting from exposure.
Where risk is high, a more conservative approach (e.g. larger buffer zone) is recommended
whereas a less conservative approach (e.g. narrower buffer zone) is regarded as
appropriate where risks are low. In this assessment, risk is based on two criteria, namely (i)
the threat or potential impact of the activity on the resource, and (ii) the sensitivity of the
water resource that would be affected by the proposed development / activity. These are
integrated into a risk score which is used to inform the level of mitigation required.
It is also worth noting that the risk assessment considers both construction and operational
phases. This is important in that some risks (e.g. sedimentation) may be very high during
the construction phase but decline considerably in the operational phase while other risks
(e.g. toxic contamination) may be much higher during the operational phase. Some
mitigation measures may therefore only be necessary for a specific phase of the project and
can be removed once risk levels decline.

Preliminary Guideline for the Determination of Buffer Zones 2014
29
7.2. Evaluate the threats posed by land use / activities on
water resources
This step involves an evaluation of the level of threat posed by
proposed land uses / activities on water resources in order to
inform the level of mitigation required. In keeping with the design criteria for the
development of this method, a basic threat assessment is initially undertaken at a desktop
level to inform decision making. This relies on generic threat tables, developed to inform
development planning. Threat ratings must however be reviewed by an aquatic specialist as
part of the site-based assessment.
Generic threat tables have been developed for this assessment for both construction and
operational phases across a wide range of sectors and subsectors ranging from agriculture
to industry and mining activities (Table 12). Wherever possible, activities have been
grouped into uniform classes based on the primary threat type identified (e.g. mining
activities have been grouped according to the risk of toxic contaminants (Mining Hazard
Classes – DWAF (2007)). For a full description of sub-sectors, please see Annexure 6.
Desktop Site-based
Y Y

Preliminary Guideline for the Determination of Buffer Zones 2014
30
Table 13. List of Sectors and sub-sector land use classes / activities
SECTOR
Agriculture Industry Mixed-use
/Commercial/
Retail/Business
Civic and
Social Residential Open space Transportatio
n Service infrastructure Mining
SUB-SECTOR LAND USE CLASSES / ACTIVITIES
Forestry/timber High-risk Chemical
industries Core Mixed-use
Government
and
municipal
Residential Low
impact / Residential
only
Parks and gardens Paved roads
Above-ground
communication/power
(electricity) infrastructure
Prospecting (all
materials)
Nurseries and tunnel
farming operations Chemical storage facilities Medium Impact
Mixed-use
Place of
worship
Residential Medium
Impact Sports fields Unpaved
roads
Below-ground
communication/power
(electricity) infrastructure
High-risk mining
operations
Dryland commercial
cropland (Annual)
Drum/container
reconditioning
Low Impact Mixed-
use Education High density urban Golf courses –
fairways Paved trails Hazardous waste
disposal facility
Moderate-risk mining
operations
Dryland commercial
cropland (Longer
rotation)
Paper, pulp or pulp
products industries
Multi-Purpose
Retail and Office Cemetery Resort
Golf courses – tee
boxes and putting
greens
Unpaved
tracks and
trails
General solid waste
disposal facility
Low-risk mining
operations
Irrigated commercial
cropland Petroleum works Petrol station / Fuel
depot
Health and
Welfare Hotel Maintained lawns
and gardens Parking lots Sewage treatment works
Plant and plant waste
from mining operations –
high risk activities
Subsistence cultivation Livestock processing
operations
Maintenance and
repair
facilities
Informal settlements
Airport –
runways and
taxiways
Sludge dams associated
with concentrated
livestock operations
Plant and plant waste
from mining operations –
moderate risk activities
Extensive livestock
grazing operations
Medium-risk Chemical
industries Offices Residential High
Impact Railway
Pipelines for
transportation of
hazardous substances
Plant and plant waste
from mining operations –
low risk activities
Intensive livestock
grazing operations Ceramic works
Pipelines for the
transportation of waste
water
Moderate-risk quarrying
operations
Concentrated livestock
operations
Electricity generation
works
Low-risk quarrying
operations
Aquaculture or marine
culture
Timber milling or
processing works Exploratory drilling
Dredging works
Cement/concrete works
Breweries/distilleries
Industries processing
livestock derived products
Composting facilities

Preliminary Guideline for the Determination of Buffer Zones 2014
31
Threats posed by lateral (diffuse) surface inputs were qualitatively assessed on the level of threat
posed by land use activities associated with each sub-sector on the following aspects:
• Water Quantity
– volumes of flow
• Water Quantity
– patterns of flow
• Sedimentation and turbidity
• Water Quality
– Increased inputs of nutrients
• Water Quality
– Increased toxic contaminants
• Water Quality – changes in pH
• Water Quality – concentration of salts (salinization)
• Water Quality – temperature
• Water Quality – pathogens (i.e. disease-causing organisms)
This threat assessment was informed as far as possible by an understanding of current legal
obligations for managing impacts to water resources. Although diffuse source impacts are not
specifically regulated at present, wastewater discharges are currently regulated through a licensing
process. A General Authorization6 has been issued for activities disposing <2000 l/day provided it
complies with the wastewater limit values7 defined in the General Authorization. The authorization
defines both general wastewater limit values (GLVs), set for non-listed water resources and stricter
special wastewater limit values (SLVs) set for listed water resources requiring more careful
management. Given that diffuse-source impacts can have a similar effect to wastewater; these limits
were used to inform the threat ratings applied in the threat assessment.
This concept is further illustrated in Figure 5, below. The diagram shows a container filled with
diffuse source discharges of varying pollutant loadings which reflects the level of threat posed by a
development. Where discharge concentrations are likely to be below SLV levels, threat is regarded
as very low (as represented by a small volume in the cup), while a discharge up to the GLV limit is
considered low, in line with current general authorizations. Additional threat classes are defined
based on the anticipated exceedance of GLV standards in diffuse runoff from a development in the
absence of mitigation as reflected by increasing volumes of water in the container.
The threat rating applicable is provided in Table 14 below and includes reference to GLVs and
SLVs. For more details of the specific limits set for evaluating different threat types, see Annexure 7
of this document.
6 Government Notice 399. Revision of General Authorizations in terms of Section 39 of the National Water Act, 1998 (Act
no. 36 of 1998).
7 According to the National Water Act, "wastewater limit value" means the mass expressed in terms of the concentration
and/or level of a substance which may not be exceeded at any time. Wastewater Limit Values shall apply at the last point
where the discharge of wastewater enters into a water resource, dilution being disregarded when determining compliance
with the wastewater limit values. Where discharge of wastewater does not directly enter a water resource, the wastewater
limit values shall apply at the last point where the wastewater leaves the premises of collection and treatment.

Preliminary Guideline for the Determination of Buffer Zones 2014
32
Figure 5. Diagram illustrating how threat classes have been related to SLV & GLV limits.
Table 14. Ratings used to evaluate the level of threat posed by diffuse surface runoff from various
land uses / activities located adjacent to water resources.
THREAT RATING SYMBOL THREAT SCORE DESCRIPTION
Very Low VL 0.2
The level of threat (based on likelihood, magnitude and
frequency of potential impacts) posed by the land use /
activity to water resources is very low for the threat type
assessed. In the case of water quality impacts, SLV
limits are unlikely to be exceeded in diffuse surface
runoff.
Low L 0.4
The level of threat posed by the land use / activity to
water resources is low for the threat type assessed. In
the case of water quality impacts, GLV limits are unlikely
to be exceeded in diffuse surface runoff.
Moderate M 0.6
The level of threat posed by the land use / activity to
water resources is moderate for the threat type
assessed. If not managed, pollutant loads in diffuse
surface runoff may range up to 5x the GLV limit.
High H 0.8
The level of threat posed by the land use / activity to
water resources is high for the threat type assessed. If
not managed, pollutant loads in diffuse surface runoff
may range up to 10x the GLV limit.
Very High VH 1
The level of threat posed by the land use / activity to
water resources is very high for the threat type
assessed. If not managed, pollutants loads in diffuse
surface runoff may exceed 10x the GLV limit.
The threat assessment was initially carried out through an expert-workshop, mostly comprising
DWA personnel. In the case of potential water-quality impacts, land use threats were evaluated
based primarily on the anticipated pollutant loading from surface runoff although the effects of land
uses on runoff characteristics (e.g. increased surface runoff in land uses characterised by hardened
surfaces or bare ground) was also considered. This process was also informed by quantitative
Threat Rating
SLV
GLV
5 x GLV
10 x GLV
Very Low
Low
Moderate
High
Very High

Preliminary Guideline for the Determination of Buffer Zones 2014
33
information pertaining to the Event Mean Concentration8 values obtained from research undertaken in
the United States (Environmental Protection Agency, 2001; and Lin, 2004). EMCs are reported as a
mass of pollutant per unit volume of water (usually mg/l), which allowed these values to be
compared against wastewater limit values. A summary of the average EMC values from a range of
studies is provided in Annexure 8, with further details from specific studies included in Annexure 9.
It is also important to note that a conservative approach was taken when undertaking this
assessment by considering the realistic “worst-case” scenario but given standard accepted
management measures where appropriate9. For example, for extensive livestock grazing, the
ratings applied were by considering potential risks associated with an extensive grazed system
having stocking rates up to (but not exceeding) maximum carrying capacity.
Preliminary threat ratings were then reviewed and refined by the specialist team during the
development and further refinement of the buffer zone model. The outcome is a rating of threats of
each sector and sub-sector for the range of potential threats identified (Annexure 10). These ratings
form a key driver for establishing the risk posed by land uses / activities on water resources as part
of this assessment10. When using the buffer zone tools, the assessor simply selects the sector and
appropriate sub-sector relevant to the assessment, and desktop threat ratings are auto-populated
for each threat type. The threat assessment is used in different ways, depending on the level of
assessment being undertaken:
• Desktop assessment: Where the specific sub-sector is unknown, threat ratings are based on
the worst-case threat ratings for all sub-sector activities. If the sub-sector is known, sub-sector
threat ratings are used to provide a preliminary indication of the level of threat posed by land
uses / activities on water resources.
• Site-based assessment: Desktop sub-sector-specific threat ratings are used to guide the
selection of a specialist threat rating based on available knowledge of the nature of the planned
development. While desktop threat ratings provide an indication of the level of threat posed by
different land uses / activities, there is likely to be some level of variability between activities
occurring within a sub-sector. It is therefore important that these threat ratings be reviewed
based on specialist input for the site-based assessment and that a justification for any
changes is also documented. When reviewing the threat ratings, the following aspects should
be considered:
• Development-specific information: Specific knowledge about the planned
development may provide a strong basis for refining desktop threat ratings.
• Intensity of development: While desktop scores have been rated based on a realistic
worst-case scenario, there may be justification to reduce threat scores in instances
8 “Event Mean Concentration “is defined as the mean concentration of pollutants in the runoff from a storm event. EMCs
are typically used for calculating runoff pollutant loads for watersheds based on the occurrence of landuse types present.
9 When assessing threat at a desktop level, the following assumptions should be made:
- The development being planned is directly adjacent to the water resource (no buffer in place);
- The sub-sector assessed is the dominant landuse and occurs at intensities typical of the sub-sector;
- Where intensities are variable (e.g. informal development / subsistence cultivation), the typical realistic worst-case
scenario should be assessed;
- In the case of sub-sectors that address linear developments (e.g. footpaths / roads); threats should be assessed based
on typical width and characteristics of the specific sub-sector and associated construction and operational activities.
10 It is important to note here that desktop threat ratings were developed in a workshop environment using individuals with
an understanding of difference sectors. In some situations however, confidence in ratings applied was poor, requiring
further consideration. While these preliminary scores were updated through further input from the project team, it is
anticipated that these desktop threat ratings will be reviewed over time and be used to update the buffer zone model
accordingly.

Preliminary Guideline for the Determination of Buffer Zones 2014
34
where development density / intensity is considerably lower than that typical for the sub-
sector.
• Site attributes: There may be situations where site attributes such as slope steepness,
slope length, soil depth and soil erodibility exacerbate potential impacts at a site level.
It is important to emphasize that aquatic impact buffer zones are designed to ensure that threats are
internalized and appropriately mitigated by each and every development, irrespective of scale. It is
only by adopting this precautionary approach, that cumulative impacts can be managed over the
long-term. The threat of a small industrial site or residential development being planned adjacent to
a water resource is therefore treated the same as if this land use was planned along the entire
perimeter of the water resource. As such, threat ratings should not be reduced simply on the basis
of the scale of the planned development relative to the water resource under investigation. This
would however have an impact on the significance ratings calculated as part of any impact
assessment process.
Refined threat ratings should be based on standard accepted management and operational
practices. A range of additional management and mitigation measures can also be used to motivate
for a reduction in the levels of threat posed by different land uses. These are catered for later in the
assessment through the identification and implementation of additional site-specific mitigation
measures (See Section 7.10).
As previously indicated, it is also important to note that this threat assessment is restricted to an
assessment of threats posed by pollutants in diffuse surface runoff. An assessment of other key
threats including (i) threats to groundwater and (ii) threats from point-source discharges was not
considered. These aspects also need to be considered by the aquatic specialist when defining
mitigation measures to reduce potential impacts to water resources.
Buffer zone tool:
• Depending on the level of assessment, select the “Sector” and/or “Sub-sector” for the activity
being investigated.
• For the site-based assessment, review desktop threat ratings and capture specialist threat
ratings based on best-available information.
• Provide a justification for any deviations to desktop threat ratings.
7.3. Integrate climatic factors into the threat
assessment
While potential impacts to water resources are driven primarily by the threats associated with
different land use / activities, surface runoff and associated contamination risk is also influenced by
climatic factors. Indeed, in areas of higher mean annual precipitation (MAP) (Figure 6) and
characterized by more intense rainfall events (Figure 7) the frequency and intensity of surface
overland flow will be higher than in climates characterized by low rainfall and less intensive rainfall
events. This was clearly demonstrated in a hydrological simulation study undertaken for this project
(Annexure 11).
In order to account for this variability, the threat score used to inform buffer zone determination is
adjusted to account for these basic climatic factors. This is accounted for in the buffer zone model
Desktop Site-based
Y Y

Preliminary Guideline for the Determination of Buffer Zones 2014
35
which calculates a “Climate Risk Score” that reflects the variability in peak discharges anticipated as
a result of changes in the climatic criteria relative to “Reference” conditions which were taken as a
MAP range of 1000-2000 mm and a moderately high rainfall intensity zone (Zone 3). The climatic
risk score11 is calculated based on the modifiers for MAP and the rainfall intensity zone in which the
land use / activity is proposed (Table 15).
Figure 6. Mean annual precipitation (Adapted from Schulze et al., 2007)
11 Climatic risk score is calculated by multiplying the modifiers for MAP and rainfall intensity and normalizing these
values to a range from 0-1.

Preliminary Guideline for the Determination of Buffer Zones 2014
36
Figure 7. Rainfall intensity zones based on one day design rainfall over a two year return
(Adapted from Schulze et al., 2007)
Table 15. Modifiers used to calculate a Climate Risk Score.
MEAN ANNUAL
PRECIPITATION
(MAP)
Class 0-400
mm 401-600
mm 601-800
mm 801-1000
mm 1001-
1200 mm >1201
mm
Modifier 0.01 0.25 0.5 0.75 1.0 1.25
RAINFALL
INTENSITY
ZONE
Category Zone 4 Zone 3 Zone 2 Zone 1
Modifier 1.25 1.0 0.75 0.5
The threat score is then adjusted automatically in the buffer zone model by applying an adjustment
factor based on the climate risk score12. This effectively increases the threat ratings in high rainfall
environments or areas located within intense rainfall intensity zones13.
12 Note that the degree of alteration in flow volumes (MAR) and flow patterns are linked primarily to landuse attributes
and are unlikely to be significantly altered by climatic factors. As such, climatic factors were not used to adjust the
threat ratings for these two potential impacts types.
13 Typical pollutant loading of different landuses (as expressed by the desktop threat score) is regarded as being of
overriding importance when assessing buffer zone requirements. However, given that storm flow is the primary
mechanism for diffuse pollutant inputs, climatic factors have also been integrated into the model. The influence of
climatic factors on buffer requirements has been moderated by restricting the change in threat score to a maximum of
one threat class. By following this approach, buffer zone requirements for landuses in arid climates with low rainfall
intensities therefore score one threat class less that when the same landuse is located in a moist climates characterized
by intense rainfall events.

Preliminary Guideline for the Determination of Buffer Zones 2014
37
Buffer zone tool:
• Select the appropriate MAP class for the area under investigation.
• Select the appropriate rainfall intensity zone for the region.
• Based on this information, threat scores are automatically adjusted to account for climatic
factors.
7.4. Assess the sensitivity of water
resources to threats posed by lateral land-
use impacts
The sensitivity of water resources to lateral impacts is another factor that affects the level of risk
posed by a development. A more conservative approach is therefore required where proposed
developments take place adjacent to water resources which are sensitive to lateral impacts as
opposed to the same development taking place adjacent to a water resource which is inherently
less sensitive to the impacts under consideration. For example: Agriculture, posing a high siltation
threat may be planned alongside a small and isolated depression wetland (pan) that is highly
sensitive to lateral sediment inputs. The risk posed by agricultural activities in this instance is far
higher than for agricultural activities adjacent to a large floodplain wetland, characterized by
inherently high natural sediment inputs.
The assessment of sensitivity is based on key attributes of different water resources that act as
easily measurable indicators14. The sensitivity assessment has therefore been tailored for wetlands,
rivers and estuaries. Sensitivity scores and classes used in the assessment are described in
Table 16.
Table 16. Sensitivity classes used to guide the assessment of sensitivity of water resources to
lateral impacts.
SENSITIVITY CLASS SYMBOL SENSITIVITY
SCORE DESCRIPTION
Very Low VL 0.85 Water resource is likely to have a very low susceptibility
to the specific impact type.
Low L 0.93 Water resource is likely to have a low susceptibility to the
specific impact type.
Moderate M 1.00 Water resource is likely to be moderately susceptible to
the specific impact type.
High H 1.08 Water resource is likely to have a high susceptibility to
the specific impact type.
Very High VH 1.15 Water resource is likely to have a very high susceptibility
to the specific impact type.
It is important to point out that this assessment is designed to assess the inherent sensitivity of the
water resource, rather than the sensitivity of important biota that may be reliant on the water
resource. Where important biodiversity elements are present, buffer requirements are adjusted to
account for these features (See Section 8.1).
14 It is important to point out that this assessment is different to that used to define EIS, as the focus is specifically on
the sensitivity of water resources to lateral impacts rather than broader catchment impacts.
Desktop Site-based
Y

Preliminary Guideline for the Determination of Buffer Zones 2014
38
7.4.1. Assessing the sensitivity of wetlands to lateral land-use inputs
The sensitivity of wetlands to lateral impacts is assessed using a range of indicators outlined in
Table 17, below. For details on the rationale for indicator selection, scoring criteria and method of
assessment, refer to the guidelines included in Annexure 12. The rationale and method of
assessment is also captured as comments in the buffer zone models.
Table 17. Indicators used to assess the sensitivity of wetlands to lateral land use impacts
INDICATOR
Overall size
Size of the wetland relative to (as a percentage of) its catchment
Average slope of the wetland’s catchment
The inherent runoff potential of the soil in the wetland’s catchment
The extent to which the wetland (HGM) setting is generally characterized by sub-surface water input
Perimeter to area ratio
Vulnerability of the HGM type to sediment accumulation
Vulnerability of the site to erosion given the site’s slope and size
Extent of open water, particularly water that is naturally clear
Sensitivity of the vegetation to burial under sediment
Peat versus mineral soils
Inherent level of nutrients in the landscape
Sensitivity of the vegetation to increased availability of nutrients
Sensitivity of the vegetation to toxic inputs, changes in acidity & salinization
Natural wetness regimes
Natural salinity levels
Level of domestic use
Average temperature
7.4.2. Assessing the sensitivity of estuaries to lateral inputs
The sensitivity of estuaries to lateral impacts is assessed using a range of indicators, depending on
the threat under consideration and the level of assessment being undertaken. Indicators used to
inform this assessment are briefly outlined in Table 18, below. For details on the rationale for
indicator selection, scoring criteria and method of assessment, refer to the guidelines included in
Annexure 13. The rationale and method of assessment is also captured as comments in the buffer
zone models.
Table 18. Indicators used to assess the sensitivity of estuaries to lateral land use impacts
INDICATOR
Estuary size
Estuary length
Perenniality of river inflow
The inherent runoff potential of the soil in the estuary’s catchment
Mouth closure
Water clarity
Presence of submerged macrophytes
Level of domestic use
Average temperature

Preliminary Guideline for the Determination of Buffer Zones 2014
39
7.4.3. Assessing the sensitivity of rivers and streams to lateral inputs
The sensitivity of rivers and streams to lateral impacts is assessed using a range of indicators,
depending on the threat under consideration and the level of assessment being undertaken.
Indicators used to inform this assessment are briefly outlined in Table 19, below. For details on the
rationale for indicator selection, scoring criteria and method of assessment, refer to the guidelines
included in Annexure 14. The rationale and method of assessment are also captured as comments
in the buffer zone models.
Table 19. Indicators used to assess the sensitivity of rivers and streams to lateral land use impacts
INDICATOR
Stream order
Channel width
Perenniality
Average catchment slope
Inherent runoff potential of catchment soils
Longitudinal river zonation
Inherent erosion potential (K factor) of catchment soils
Retention time
Inherent level of nutrients in the landscape: Is the river/stream and its catchment underlain by sandstone?
Inherent buffering capacity
Underlying geographical formations
River depth to width ratio
Mean annual temperature
Level of domestic use
7.5. Assess the sensitivity of important
biodiversity elements to threats posed by
lateral land-use impacts
While the sensitivity of the water resource to threats posed by lateral inputs may be low, specific
important biota or habitats may well be sensitive to such impacts. Where relevant, it is therefore
important to consider the sensitivity of any important biodiversity elements identified in Step 5 and to
adjust the sensitivity scores accordingly. See Section 8.4 for further guidance on how biodiversity
considerations should be incorporated into an assessment of aquatic impact buffer requirements.
7.6. Determine the risk posed by proposed
activities on water resources
Once both threats posed by potential developments / activities, and
the inherent sensitivity of receiving water resources have been assessed, this information is used to
evaluate the risks posed by such activities on the water resource under consideration. Note that in
the case of a desktop assessment, water resources are assumed to have a very high sensitivity to
the full suite of potential impacts evaluated. Risk scores are calculated by multiplying threat and
Desktop Site-based
Y Y
Desktop Site-based
Y

Preliminary Guideline for the Determination of Buffer Zones 2014
40
sensitivity scores to obtain a risk score for each impact type evaluated, as illustrated in Table 20
below15.
Table 20. Table used to integrate threat and sensitivity scores into a composite risk score as part of
the buffer zone model.
INHERENT SENSITIVITY
POTENTIAL THREAT OF
LAND USE / ACTIVITY
VH H M L VL
1.15 1.08 1.00 0.93 0.85
VH 1 1.15 1.075 1.0 0.925 0.85
H 0.8 0.92 0.86 0.8 0.74 0.68
M 0.6 0.69 0.645 0.6 0.555 0.51
L 0.4 0.46 0.43 0.4 0.37 0.34
VL 0.2 0.23 0.215 0.2 0.185 0.17
From a technical perspective, it is important to note that sensitivity scores for moderately sensitive
water resources have been set at 1. This is consistent with the approach used to link risk classes
with buffer zone widths in step 3.4.2, which links required buffer zone efficiency to compliance with
GLV standards – appropriate for moderately sensitive systems. Where water resources are more
sensitive, the risk class and associated requirement for mitigation typically increases, highlighting
the need for more stringent controls (more effective buffer zones). Where sensitivity is regarded as
low however, mitigation requirements are relaxed accordingly as indicated by lower risk scores for
water resources with a low or very low sensitivity. Risk scores calculated are then grouped into one
of 5 Risk Classes for reporting purposes as described in Table 21 below.
Table 21. Risk classes used in this assessment.
RISK CLASS RISK
SCORE DESCRIPTION
Very Low <0.3 The proposed development / activity pose a very low risk to the water
resource under investigation for the threat type assessed.
Low 0.3-0.5 The proposed development / activity pose a low risk to the water resource
under investigation for the threat type assessed.
Moderate 0.51-0.7 The proposed development / activity pose a moderate risk to the water
resource under investigation for the threat type assessed.
High 0.71-0.9 The proposed development / activity pose a high risk to the water resource
under investigation for the threat type assessed.
Very High >0.91 The proposed development / activity pose a very high risk to the water
resource under investigation for the threat type assessed.
Buffer zone tool:
• For site-based assessments, collect the information necessary to assess the sensitivity of
the water resource using acceptable methods (See Annexures 12-14).
• Review sensitivity scores and select a sensitivity class for biodiversity where this is likely to
be higher than that for the water resource.
• Risk scores are automatically calculated by the buffer zone tool based on threat and
maximum sensitivity score.
15 Note that the range of sensitivity scores was refined through a sensitivity analysis of the model under a range of
scenarios (Bredin et al., 2014). This suggested that a narrow score range selected was most appropriate to cater for
variability in water resource sensitivity.

Preliminary Guideline for the Determination of Buffer Zones 2014
41
7.7. For selected impacts, determine desktop aquatic impact
buffer requirements
Up to this point, the assessment has focused on assessing the level of risk from lateral impacts
posed by proposed developments / activities on water resources. The next step requires
identification of relevant mitigation measures to address the risks identified. Although a range of
mitigation measures can be applied to address these risks, there is good scientific evidence to
indicate that the establishment of vegetated buffer zones can be very effective at addressing a
number of these impacts. As such, buffer zones are advocated as a standard mitigation
measure to reduce the impact of pollutants entering the water resource via diffuse surface
runoff.
It is important to note however that buffer zones can only assist in mitigating some of the risks
identified and that other mitigation measures may be necessary. For example, while buffers can
help to reduce the impact of afforestation on stream flow, the area of the catchment planted to
commercial species is the primary determinant of hydrological impacts. Buffers are also most
effective in reducing pollutants in diffuse surface runoff while their ability to remove pollutants from
sub-surface flows is less well documented. Buffers can also do little to address pollutants
discharged at point-sources or in concentrated flows. Buffers should therefore be seen as only one
of a suite of possible mitigation measures to reduce potential impacts of land uses / activities on
water resources. Table 22 below serves to highlight situations in which the establishment of buffer
zones can have a potentially positive impact and should be considered.
Table 22. Summary of common threats posed by adjoining land uses / activities on water resources
and typical approaches to addressing them. Instances where buffer zones can play a particularly
important role are highlighted in blue.
THREAT SOURCE OF IMPACT APPROACH FOR ADDRESSING
THREATS
Water Quantity – volumes of
flow
Reduction in water
inputs
Source directed controls
Restricting surface flow requirement (SFR)
activities (including application of buffer
zones)
Increase in water inputs Control of water inputs (e.g. piped water)
and other mitigation measures
Water Quantity – patterns of
flow
Concentrated flows Address through on-site Best Management
Practices (BMPs) and mitigation measures
Diffuse runoff BMPs to control runoff and mitigation
measures (including buffer zones) to
address increased storm flows
Sedimentation and turbidity Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff Buffer zone together with other mitigation
measures and BMPs
Water Quality – Increased inputs
of nutrients
Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff Buffer zone together with other mitigation
measures and BMPs
Water quality – Increased
organic contaminants
Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff Buffer zone together with other mitigation
measures and BMPs
Water quality – Increased toxic
contaminants (heavy metals) Concentrated flows Address through on-site BMPs and
mitigation measures

Preliminary Guideline for the Determination of Buffer Zones 2014
42
THREAT SOURCE OF IMPACT APPROACH FOR ADDRESSING
THREATS
Diffuse runoff Buffer zone together with other mitigation
measures and BMPs
Water quality – changes in
acidity (pH) Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff
Water quality – concentration of
salts (salinization) Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff
Water quality – temperature Concentrated flows Address through on-site BMPs and
mitigation measures (including maintenance
of riparian zones).
Diffuse runoff
Water quality – pathogens (i.e.
disease-causing organisms)
Concentrated flows Address through on-site BMPs and
mitigation measures
Diffuse runoff Buffer zone together with other mitigation
measures and BMPs
While the risk assessment has been undertaken for a wide suite of potential impacts, buffer zone
requirements are only advocated where scientific studies have shown that they can be an effective
mitigation measure. Buffer zone recommendations are therefore calculated for the following
potential impacts associated with diffuse lateral surface water inputs:
• Increased sedimentation and turbidity ;
• Increased nutrient inputs;
• Increased organic contaminants;
• Increase toxic contaminants (heavy metals); and
• Increased pathogen inputs.
A buffer zone identified to perform these functions is referred to as an Aquatic impact buffer zone as
defined below:
Aquatic Impact Buffer Zone: A zone of vegetated land designed and managed so
that sediment and pollutant transport carried from source areas via diffuse surface
runoff is reduced to acceptable levels.

Preliminary Guideline for the Determination of Buffer Zones 2014
43
7.8. Determine preliminary aquatic impact
buffer zone widths required to mitigate risks
identified
Determining the required buffer width is largely an exercise in assessing the situation and linking it
to an acceptable level of risk. In this approach, threats have already been defined for each of the
required buffer functions with reference to existing standards (Table 14). The determination of
buffer zone widths is therefore guided by the level of effectiveness required to mitigate risks to
acceptable limits. The relationship between risk classes and buffer zone effectiveness is illustrated
in Table 23 below.
Table 23. Guideline for linking buffer width with buffer zone effectiveness
RISK EFFECTIVENESS
(%) RATIONALE
Very Low 25
Threats are either low or very low and associated with water resources of
moderate to very low sensitivity. Although no buffer is necessarily
required, a minimum buffer zone providing a minimum level of
effectiveness is advocated.
Low 50 Risks are regarded as low based on anticipated threats and sensitivity of
the water resource. A narrow buffer zone providing some level of
protection is advocated to reduce risks to an acceptable level.
Moderately
low 80
Risks are regarded as moderately low based on anticipated threats and
sensitivity of the water resource. In this case, a buffer zone that is 80%
effective will be necessary to reduce impacts to within an acceptable
target range.
Moderately
High 90
Risks are regarded as moderately high based on anticipated threats and
sensitivity of the water resource. In this case, a buffer zone that is 90%
effective will be necessary to reduce impacts to within an acceptable
target range.
High 95 Risks are regarded as high based on anticipated threats and sensitivity of
the water resource. In this case, a buffer zone that is at least 95%
effective will be necessary to reduce impacts to within GLV requirements.
Very High 98
Risks are regarded as very high based on anticipated threats and
sensitivity of the water resource. In this case, a buffer zone that is at
least 98% effective will be necessary to reduce impacts to within GLV
requirements. In many cases, this will not be achievable and therefore
the implementation of additional alternative mitigation measures will be
required.
Rule-curves have been developed, based on the best available science to link buffer width and
buffer effectiveness. These relationships are summarized below, while further information, including
reference to relevant studies that support these relationships is included in Annexure 15 of this
report16.
These relationships assume that buffer width is the most important factor for effective mitigation,
which is consistent with findings in the international literature (e.g. Phillips, 1989). Other factors that
affect buffer zone efficiency such as slope and vegetation cover are not explicitly considered at this
stage but are dealt with later at a site level (See Section 7.9). Details of each of the relationships
used to establish preliminary buffer requirements are presented here.
16 It is important to note here, that these rule curves have been developed based on a suite of default or “reference” buffer
zone attributes (See Section 7.10). Site specific buffer requirements may therefore vary considerably in response to local
buffer zone attributes that affect the effectiveness of buffers to trap pollutants.
Desktop Site-based
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Preliminary Guideline for the Determination of Buffer Zones 2014
44
Desktop aquatic impact buffer zone requirements are automatically calculated in the buffer zone
model based on the level of risk defined for each of the four potential impacts considered17. The
aquatic impact buffer zone width required is then taken as the maximum of the buffer zone widths
proposed for each of the potential impacts evaluated.
7.8.1. Increased sedimentation and turbidity
Numerous studies have been undertaken to assess the effectiveness of buffer zones in retaining
sediments washed off in surface runoff. These suggest that the relationship between the length
covered by the runoff (buffer width) and sediment removal is not linear, with most sediment being
deposited in outer portions of the buffer. Although there is considerable variation in reported
efficiencies it is clear that high efficiencies can be obtained from small (<10 m) buffer zones but that
wider buffer zones are required to effectively remove greater amounts of suspended sediment.
Based on a review of available literature, standard buffer widths of between 2 m and 50 m have
been proposed for sediment removal, depending on the effectiveness of the buffer zone required
(Figure 8).
Figure 8. Relationship between (a) sediment removal efficiency and buffer width and (b) risk of
sediment inputs and buffer requirements used to calculate aquatic impact buffer requirements
(m).
7.8.2. Increased nutrient inputs from lateral inputs
Many studies have shown that buffer zones can be very effective at removing nitrogen and
phosphorous from lateral water inputs. Although removal effectiveness varied widely among
studies, there is a clear relationship between buffer width and buffer effectiveness. As with
sediment removal, a curvilinear relationship is typically used to describe the relationship between
buffer width and nutrient removal efficiency. This relationship is presented in Figure 9, below and
suggests that high levels of buffer efficiency can be achieved with small buffers of < 20 m in width.
Very wide buffers may however be necessary to effectively remove nutrients in high risk situations.
17 Given the importance of following a precautionary approach when calculating desktop buffer requirements, buffers have
been determined based on a worst-case scenario. This assumes that the receiving water resource is very sensitive
(maximum sensitivity score) and that the characteristics of the buffer zone are poorly suited to address diffuse source
pollutants (worst case site-based attributes).
0
10
20
30
40
50
60
70
80
90
100
0 102030405060
Removal efficiency (%)
Buffer Requirement
y = 69.643x
2
- 23.071x + 3.6
R² = 0.9997
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Buffer Requirement
Risk Score
(a) (b)

Preliminary Guideline for the Determination of Buffer Zones 2014
45
Figure 9. Relationship between (a) nutrient removal efficiency and buffer width and (b) risk of
nutrient inputs and buffer requirements used to calculate aquatic impact buffer requirements.
7.8.3. Increased toxic contaminants from lateral inputs
Toxic contaminants cover a broad suite of potentially toxic substances. These include toxins
(including toxic metal ions (e.g. copper, lead, zinc, etc.), toxic organic substances (which reduce
oxygen availability), hydrocarbons, and pesticides. In addition, the efficiency of a buffer at trapping
toxic substances is dependent on a wide range of factors, such as residence times, flushing rates,
dilution and re-suspension rates of the toxic substances.
As an initial approach to determining the effectiveness of a buffer zone at trapping toxic substances,
toxic contaminants have been considered as two broad categories, namely organic contaminants
(which include pesticides) and toxic heavy metals. Buffer widths proposed for these groups have
been based on available information. In addition, the precautionary principle was also applied.
These relationships are presented in Figures 10 and 11 respectively and suggest that for toxic
metals high levels of buffer efficiency can be achieved with small buffers (i.e. approximately 20 m in
width). However, wider buffers (i.e. up to 80 m) may be necessary to effectively remove toxic metals
in high risk situations. For organic pollutants, including pesticides, a buffer of 20 m would also be
effective. However, for high risk situations a larger buffer would be required (i.e. a buffer of
approximately 40 m).
Figure 10. Relationship between (a) toxic metal removal efficiency and buffer width and (b) risk
of toxic metal inputs and buffer requirements used to calculate aquatic impact buffer
requirements.
0
10
20
30
40
50
60
70
80
90
100
0 20406080100120
ERemoval efficien cy (%)
Buffer requirement
y = 176.79x
2
- 91.643x + 13.6
R² = 0.9968
0
20
40
60
80
100
120
0 0 .2 0.4 0.6 0 .8 1
Buffer Requirement
Risk Scor e
(a) (b)
(a) (b)

Preliminary Guideline for the Determination of Buffer Zones 2014
46
Figure 11. Relationship between (a) organic pollutants and pesticide removal efficiency and
buffer width and (b) risk of organic pollutants and pesticide inputs and buffer requirements used
to calculate aquatic impact buffer requirements.
7.8.4. Increased pathogen inputs from lateral sources
Studies undertaken on the effectiveness of buffers at removing pathogens suggest that small
buffers may be effective in performing this function. Based on the information available, maximum
recommended buffers for pathogen removal were set at 30 m, reduced to 2 m in the case of low-risk
activities. Given that research suggests that very small buffers are effective at removing pathogens,
a curvilinear relationship was again assumed as illustrated in Figure 12, below.
Figure 12. Relationship between (a) pathogen removal efficiency and buffer width and (b) risk of
pathogen inputs and buffer requirements used to calculate aquatic impact buffer requirements.
Buffer zone tool:
• Preliminary buffer zone requirements for construction and operational phases are
automatically calculated for each threat type based on risk ratings already calculated.
• The maximum of the buffer widths for construction and operational phase can be used to
define desktop buffer requirements.
7.9. Refine preliminary buffer requirements
based on site-based investigations
While buffer width is widely regarded as the most important factor in determining the level of
effectiveness of buffer zones, large variations in effectiveness can be explained by site-specific
differences. The characteristics of the buffer zone either detract from or contribute to specific
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35
ERemoval efficien cy (%)
Buffer requirement
y = 35.714x
2
- 6.8571x + 1.6
R² = 0.9967
0
5
10
15
20
25
30
35
0 0 .2 0.4 0.6 0.8 1
Buffer Requ irement
Risk Score
Desktop Site-based
Y
(a) (b)
(a) (b)

Preliminary Guideline for the Determination of Buffer Zones 2014
47
functions. As such, it is important to also consider site-based buffer attributes when determining
appropriate buffer requirements.
For the site-based assessment, site-specific buffer characteristics are therefore also included and
are used to adjust the preliminary buffer requirements already calculated. Based on the literature
review undertaken and practicalities associated with undertaking a buffer zone assessment, four
buffer zone attributes were selected to refine buffer zone requirements at a site level. These
included:
• vegetation characteristics;
• slope;
• soil permeability; and
• topography.
Details of why these criteria were selected together with further guidance on undertaking the
assessment are detailed for each buffer zone function in Annexure 16. Buffer width “Modifiers” are
defined for each buffer characteristic based on the anticipated effect of possible attributes on buffer
zone effectiveness across different buffer functions. These characteristics are rated relative to
default or “Reference” buffer characteristics18.
To undertake this assessment, variability in buffer zone attributes must be assessed during the site
visit. This assessment should focus on buffer characteristics within 50 m of the delineation
line from which aquatic impact buffer zones are determined. In the case of small sites, it
should be feasible to describe buffer attributes that reflect typical buffer characteristics for the site as
a whole. In many instances however, there may be significant variability in buffer zone
characteristics that need to be accounted for. In such an instance, existing buffer zones should be
sub-divided into discrete segments with comparable buffer zone attributes. Buffer
characteristics should then be described by selecting buffer attributes in the buffer zone tool that
best reflects local buffer attributes for each buffer segment. In the case of vegetation, buffer
attributes should be assessed according to current characteristics for the construction phase. If
specific management measures are proposed to rehabilitate or in any other way alter vegetation
attributes during the operational phase, these must also be captured in the tool and be specifically
addressed as management measures.
The buffer zone model then calculates a modifier rating for each buffer zone function19 which is
used to adjust the preliminary buffer zone recommendation for each of the buffer segments
identified20.
18 “Reference” buffer zone attributes were defined as follows:
• Slope of buffer: Moderate (10.1-20%);
• Vegetation characteristics (basal cover): High (Dense vegetation, with good basal cover (e.g. natural grass stands));
• Soil permeability: Moderate. Moderately textured soils (e.g. sandy loam);
• Topography of the buffer zone: Dominantly smooth topography with few/minor concentrated flow paths to reduce
interception.
19 Site-based modifiers are determined by calculating a weighted average of site factors. The weighting applied to each
criterion was informed by available literature on the importance of different buffer zone attributes in determining buffer
zone effectiveness. The following weightings were applied to slope; vegetation characteristics; soil permeability and buffer
topography respectively:
• Sedimentation & turbidity (2;1.5;1;1);
• Nutrient inputs: (2;2;1;1);
• Toxic organic contaminants (2;1.5;1;1);
• Toxic metal contaminants (2;1.5;1;1); and

Preliminary Guideline for the Determination of Buffer Zones 2014
48
Buffer zone tool:
• Capture the site attributes for each buffer segment identified.
• Site-Based modifier scores are used to automatically refine the preliminary buffer
requirements for each potential threat considered.
• Site-based aquatic impact buffer requirements for construction and operational phases are
then automatically calculated based on the maximum of the buffer width requirements for all
the threat types considered.
7.10. Where appropriate, identify additional
mitigation measures and refine aquatic
impact buffer width accordingly
While buffer zones are advocated as standard mitigation measures to address a range of threats,
they are only one of a suite of mitigation measures that can be used to reduce potential impacts.
Indeed, pollution prevention and on-site mitigation (e.g. water treatment / water reuse and
reclamation) are regarded as preferable rather than simply relying on a buffer zones as a last form
of defence to address these impacts. It may also be desirable to reduce the buffer zone
requirement by implementing additional complementary mitigation measures that reduce threats
and associated buffer zone requirements.
To help practitioners identify suitable additional complimentary mitigation measures, a range of
potential mitigation options have been identified from existing literature. These have been
consolidated into a user-friendly Excel-based “Mitigation Measures Tool”21. An overview of the
mitigation measures tool is provided in Annexure 17. The look-up lists provided in this tool can be
used to identify a suite of potential additional mitigation measures for different impact types that are
relevant to the sector of interest.
Based on an understanding of the effectiveness of proposed mitigation measures, refined threat
ratings are selected for the affected risks, together with appropriate justifications. For risks that
have a bearing on buffer zone width, buffer zones are adjusted accordingly to obtain a revised
aquatic impact buffer zone requirement.
Buffer zone tool:
• Consult the “Mitigation Measures Tool” and supporting references to identify potential
mitigation measures that could be used to reduce the key risk(s) identified.
• Where relevant, describe additional mitigation measures to be implemented to address risks
associated with construction and operational phases of the proposed development/activity.
• Where appropriate, select a refined threat rating and document the justification for the
revised ratings based on an understanding of the effectiveness of mitigation measures
proposed.
• A refined risk rating is automatically calculated, and is used to update buffer zone
requirements.
• Pathogens (2;1.5;1;1).
20 It is important to note here that maximum buffer zone widths were integrated into the model to limit the possible upper
range of buffer recommendations in line with those cited in the literature report (Annexure 1). In the case of sediment
retention, a maximum buffer of 125 m is applied whilst values of 260 m and 90 m were applied for nutrient and pathogen
removal respectively. In the case of toxics contaminants, a maximum of 200 m was applied.
21 The “Mitigation Measures Tool” is included in the attached CD.
Desktop Site-based
Y

Preliminary Guideline for the Determination of Buffer Zones 2014
49
7.10.1. Review and refine aquatic impact buffer requirements to
cater for practical management considerations
While the buffer zone tool provides a recommended buffer width to address potential risks from
adjacent land use activities, it is essential that buffer zones cater for risks of buffer zone failure and
are sufficiently wide to allow the buffer and any important attributes to be managed and maintained.
In a study on the use and effectiveness of buffer zones, Castelle et al. (1992) found that nearly all of
the buffers assessed that were less than 15 m in width were significantly reduced within a few
years, and some were found to have been eliminated through complete clearing of indigenous
vegetation. Of the buffers assessed that were wider than 15 m, most still had some portion intact
and generally exhibited fewer signs of human disturbance. The risk of poor management is likely to
be particularly high in contexts characterized by low management capacity (e.g. low-cost housing
developments) or in areas subject to high levels of use (e.g. in peri-urban areas where vacant land
is often used for subsistence cultivation).
In addition, a review of recommended minimum buffer zones (i.e. different types of buffer zones)
revealed that the most frequently recommended minimum buffer zones width was 15 m (Table 24).
Table 24. Review of different buffer types and the recommended minimum buffer zone widths
Buffer type Minimum buffer zone
width (m) Reference
Vegetated filter strip 30 Barling & Moore 1994
Vegetated filter strip 11 Corbert et al., 1978
Vegetated filter strip 20 Department of Conservation
and Environment 1990
Forested riparian buffer 15 Blinn & Kilgore 2001
Forested riparian buffer 15 Bray 2010
Grass filter strip and vegetated buffer 35 Hansen et al., 2010
Vegetated filter strip 5 Hawes & Smith 2007
Vegetated filter strip 20 Ives et al., 2005
Vegetated filter strip 15 Lee et al., 2004
Vegetated filter strip 10.7 Lowrance et al., 2001
Vegetated filter strip 50 Mayer et al., 2007
Forested buffer strip 15 Palone & Todd 1997
Vegetated filter strip 27 Parkyn 2004
Vegetated filter strip 10 Parkyn et al., 2000
Vegetated filter strip 30 Castelle et al., 1994
Vegetated filter strip 45 Brosofske et al., 1997
Forested buffer strip 9 Schultz et al., 2004
Grass filter strip and vegetated buffer 15 Semlitsch & Bodie 2003
Vegetated filter strip 15 Technology Associates 2010
Forested buffer strip 11 Tjaden & Weber 1998
Riparian buffer strip 15 Wegner 1999
Hardwood buffer 15 Woodard & Rock 1995
Vegetated filter strip 25 Young et al., 1980

Preliminary Guideline for the Determination of Buffer Zones 2014
50
Buffer type Minimum buffer zone
width (m) Reference
Grass filter strip and vegetated buffer
strip 61 Horner and Mar, 1982
Grass filter strip 9 Ghaffarzader et al., 1992
Grass filter strip 5 Madison et al., 1992
Vegetated filter strip 9 Dillaha et al., 1989
Grass filter strip 18 Nichols et al., 1998
Grass filter strip and forested buffer 4 Doyle et al., 1977
Forested riparian buffer 19 Shisler et al., 1987
Most frequently recommended
minimum buffer zone (m) 15
A minimum aquatic impact buffer zones of 15 m has therefore been integrated into the buffer
zone models to help cater for this concern. There may however be instances where a more risk
adverse approach is required to cater for potential deterioration in buffer conditions (particularly
vegetation cover) over time22. In this instance, the motivation for adjusting the buffer zone upwards
should be clearly documented.
7.11. Evaluate aquatic impact buffer zone
requirements in light of management
objectives
For the purposes of this guideline, mitigation guidelines have been developed in order to reduce
potential risks to a desirable level such that water resource quality should not be compromised.
There may however be an argument to increase or reduce mitigation requirements in line with
management objectives or special local circumstances for the water resources defined in step 3.3.3.
Guidelines for interpreting these requirements are provided in Table 25 below.
Table 25. Guideline for identifying appropriate management and mitigation measures.
MANAGEMENT
OBJECTIVE GUIDELINES FOR IDENTIFYING MITIGATION AND MANAGEMENT MEASURES
Improve
Any potential risks must be managed and mitigated to ensure that no deterioration
to the water resource takes place. In addition, relevant on-site management
measures should be identified to help improve the present state of the water
resource (e.g. through rehabilitation interventions).
Maintain
Any potential risks must be managed and mitigated to ensure that no deterioration
to the water resource takes place. Standard management measures should be
implemented to ensure that any on-going activities do not result in a decline in water
resource quality.
22 Determination of more appropriate setback requirements can be informed by tweaking the buffer zone models to
account for potential changes in vegetation cover during the operational phase. This is simply done by adjusting the
vegetation attributes in the site-based attributes.
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Preliminary Guideline for the Determination of Buffer Zones 2014
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Controlled
degradation
It may be permissible to impact the water resource through the implementation of
less stringent management or mitigation measures. Where relaxation of
requirements is proposed, these would first need to be authorized by the relevant
implementing authority to prevent undue deterioration of the water resource.
While not advocated, where relaxation of buffer widths is proposed, the potential reduction in buffer
zone effectiveness can be estimated based on an understanding of the relationship between buffer
width and buffer zone effectiveness as described in this document23. This could be used by DWA to
assess to what degree relaxation of buffer zones may be acceptable.
Where an improvement in water resource quality is required, standard buffer recommendations are
appropriate but may be increased where a greater level of confidence is regarded as necessary. It
is the implementation of additional management measures (both at the site and catchment level)
that is likely to result in an improvement in water resource quality however.
Note: It should be left up to the relevant authorities to review and / or motivate for a change in
buffer requirements based on management objectives. As such, recommended aquatic impact
buffer zones should be documented without specifically considering management objectives.
8. STEP 5: ASSESS RISKS POSED BY PROPOSED DEVELOPMENT ON
BIODIVERSITY AND IDENTIFY MANAGEMENT ZONES FOR
BIODIVERSITY PROTECTION
While the protection of riparian areas and aquatic impact buffer zones may be adequate to protect
many aquatic species, such buffers may be insufficient to protect a range of aquatic and semi-
aquatic species that rely on terrestrial habitat for their survival. While this may be acceptable for
species that are not at risk, further interventions are required to ensure that important biodiversity
elements are not adversely impacted by planned land uses or activities.
While there are a number of examples in the international literature where buffers are simply
calculated as a horizontal distance from the aquatic resource boundary, such an approach does not
cater for a number of important considerations. These include:
• The location of critical habitat for the species within the aquatic resource: For some
species, this may be a small reed bed or, area of permanent wetland or open water. Under
such a scenario, simply buffering the entire water resource would over-estimate conservation
requirements for the species.
• Specific terrestrial habitat requirements of semi-aquatic species: Species are likely to have
specific habitat requirements that may not be adequately protected through the application of a
fixed-width buffer area around the resource. For example, Crowned Cranes specifically forage
in grassland areas around nest sites, avoiding wooded or transformed habitats. Identification
23 There may be some instances where a strong argument can be made for following a less conservative approach than
advocated in these guidelines. For example, an isolated lodge may be proposed on the edge of a large natural lake within
a protected area where no further development is proposed. In this instance, the risk of pollutants from this isolated
development having a significant impact on the water resource with high assimilative capacity is likely to be low. Setting a
precedent to other developers is also not an important consideration in this instance. In such an instance, recommended
setback requirements should be documented as per this guideline. A motivation for relaxing these requirements should
then be provided by the aquatic specialist in the specialist aquatic report for the proposed development.

Preliminary Guideline for the Determination of Buffer Zones 2014
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and protection of suitable grassland habitats within a reasonable distance from the nest site
would therefore be critical for the survival of this species.
• The condition of adjoining habitat: In some circumstances, very little natural habitat may
remain and, despite these areas being located a little distance from the aquatic resource,
remaining fragments of natural habitat may be critical for the survival of the species. Inclusion of
degraded areas in a buffer zone that is developed without taking this into account may therefore
provide little benefit for a species.
Rather than simply allocating “arbitrary” buffers around water resources, a more scientifically correct
approach is presented here. This includes the identification of core habitat, together with the
consideration of a range of other protection measures to limit impacts from adjoining land uses /
activities on these core habitats.
This assessment should be undertaken in parallel to the assessment of risks posed to the state and
functionality of the water resource in Step 4. The guidelines presented here, have been tailored for
aquatic and semi-aquatic species, which rely at least in part on water resources for their
persistence. The approach is however equally relevant to terrestrial species, for which a similar
assessment should be undertaken.
Note: Undertaking this assessment may be quite arduous for a developer, with financial constraints
and potentially minor impacts to water resources. The need for following this process should
therefore be informed by relevant criteria that include considerations such as:
• The type and scale of the proposed development;
• Anticipated risks associated with the development; and
• The importance of the area for biodiversity conservation.
In some situations, it may well be appropriate for the local authority or provincial conservation body
to undertake such an assessment at an appropriate scale and to identify appropriate zones for
biodiversity protection. This would certainly have significant cost-advantages over numerous site-
based assessments, where risks of not considering landscape-level processes and interactions are
also high. Such an approach would be particularly useful in development nodes where future
applications with a potential impact on biodiversity are anticipated.
8.1. Undertake a desktop assessment to
determine whether important biodiversity
elements are likely to be present
The first step required is to determine the potential occurrence of important biodiversity elements
that could be impacted by the proposed development. Important elements may include, amongst
others, threatened vegetation types, threatened animal or plant species or significant concentrations
of an important species. For a list of important biodiversity elements, users should liaise with
provincial conservation bodies to obtain a list of priority species and ecosystems requiring
protection. This requires a desktop assessment of available information, including consultation with
local stakeholders (e.g. landowners, conservancies, birding clubs, etc.). Key sources of information
that should be consulted include:
• Existing biodiversity surveys undertaken in the area;
• Provincial and local conservation plans for the area; and
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Preliminary Guideline for the Determination of Buffer Zones 2014
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• Maps of national freshwater priority areas.
If no biodiversity elements have been flagged through this investigation, no further assessment may
be required unless specifically requested by a key stakeholder (i.e. provincial conservation body or
interested and affected parties). Where important elements have been flagged, further effort is
required to determine whether or not they occur at the site and if so, what mitigation measures are
necessary to protect them.
For biodiversity elements that have been flagged, obtain information sheets where available from
provincial conservation bodies. Examples of draft information sheets for a range of biodiversity
features have been included in Annexure 18 of this report. These information sheets have been
designed to facilitate the assessment process, and include the following information:
• Scientific and common names
• Description: A description of the species to facilitate identification, including key features
that enable the species to be distinguished from similar species. Where appropriate,
reference is provided to other documents with more detailed descriptive information.
• Conservation status: This section documents the conservation status (both nationally and
internationally) together with a description of relevant criteria that informed the threat status
at a national level. Any information on legislation governing protection of the species,
including National (TOPS listing) or Provincial legislation together with any permit
requirements are also included.
• Distribution: A description of the species distribution range is provided. Where possible,
this includes a map of known and potential occurrence within South Africa. For migratory
species, appropriate descriptive information and a link to a broader distribution map are
provided where appropriate.
• Current level of protection within protected areas: This section provides an indication as
to the degree to which conservation requirements (targets) for the biodiversity element are
already accounted for through an existing protected area network. This should inform the
need for additional protection of remaining sub-populations – see priority actions section.
• Key threats to the species: Key threats to the species identified at a national / provincial
level are included to flag issues of potential concern.
• Priority actions required to protect the species: Key actions / management priorities
required to protect the species at a provincial / national level are documented. This includes
a consideration of the need / importance of protecting sub-populations outside of protected
areas.
• Guidelines for species surveys: Relevant guidelines to inform survey requirements linked
to the ecology of the species are provided in this section. This may include appropriate
seasons for sampling, reference to appropriate survey techniques and the level of expertise
required to undertake the survey. Additional information such as bird or frog calls, track and
scat descriptions are also included where possible.
• Description of core habitat characteristics: This includes areas where the species
occurs and associated areas required for the species to persist. Key habitat characteristics
are therefore identified that are required for the species to live, breed and persist. These
requirements differ for different groups of species and are therefore tailored accordingly.
This information is provided to (i) help direct survey efforts and (ii) to identify key areas of
habitat requiring protection to ensure the persistence of the species.

Preliminary Guideline for the Determination of Buffer Zones 2014
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• Guidelines for identifying and mapping core areas: Guidelines are provided to guide
decision making for the protection of sub-populations of the species where encountered.
This may include, for example, information on recommended minimum patch size or the
need to limit development within a distance from breeding areas to facilitate other life history
activities (e.g. foraging / hibernation).
• Sensitivity to potential site-based impacts: Sensitivity of the species to potential site
based impacts is provided here to inform development planning and associated activities.
This may include:
o Sensitivity to direct disturbance (human presence, noise, dust, light, physical
disturbance) from peripheral development or associated activities (e.g. tourism activities)
that need to be considered to ensure the species is not unduly disturbed.
o Sensitivity to pollutants that could have a direct effect on the species (e.g. pesticides,
nutrients, salts, etc.). These may well be higher than the sensitivity of the water
resource per-se, potentially requiring the implementation of more stringent mitigation
measures than required to protect the water resource.
o Sensitivity to factors that may affect species habitat (e.g. alteration of hydrological
regimes, burning practices.
• Key management considerations: Management measures necessary to maintain the
functionality of core habitats that need to be considered are highlighted in this section. This
includes aspects such as fire management, livestock management, management of tourism
or recreational activities, etc.
• Relevance of corridors for species persistence: An indication of the likely importance of
establishing corridors between sub-populations for the persistence of the species is
provided.
• Corridor design requirements: Where corridors are regarded as important, guidance to
inform corridor design is provided.
• References: A list of key references used to develop the information sheet is provided.
Note: There is a clear need for information sheets to be generated for all relevant biodiversity
features to assist in undertaking this assessment. It is hoped that provincial conservation bodies will
take on the responsibility of drafting and maintaining these documents. This would serve to
substantially improve biodiversity assessment by ensuring that appropriate guidance is available to
inform decision making. Where such information is lacking, relevant information will need to be
obtained from available literature to guide the assessment.
8.2. If important biodiversity elements are
likely to be present, undertake a survey to
verify them and establish the need for site-
based conservation efforts
Where the desktop assessment has flagged the potential occurrence of important biodiversity
features, a survey must be undertaken to assess whether or not the species occurs at or near the
proposed development site. The scope, timing and survey methods should be guided by an
understanding of the ecology of the species being investigated. Where possible, such information
should be included in species information sheets. Depending on the potential importance of
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connectivity, consideration should also be given to extending surveys beyond the immediate site
location to assess whether corridor design is likely to be necessary.
8.3. Identify core areas required to protect
any important biodiversity features
The primary role of identifying areas of core habitat is to ensure that such areas are set aside and
managed in an appropriate manner to ensure the persistence of important biodiversity elements. A
definition for core habitat is provided below, together with a description of key buffer functions that
would be provided for aquatic and semi-aquatic species by such areas (Table 26).
Table 26. Key buffer functions provided by a core habitat.
BUFFER
FUNCTION DESCRIPTION
Maintenance of
habitat for
aquatic species
Vegetation along stream lines provides food that supports in-stream food chains. These
areas are therefore vital for a range of aquatic species, dependent on these resources
for their survival.
Provision of
habitat for semi-
aquatic species
Many semi-aquatic species rely on both aquatic habitats and terrestrial areas for the
successful recruitment of juveniles and to maintain optimal adult survival rates. Such
areas are therefore necessary to meet the living requirements of these species and so
enable such species to persist in the area.
Identifying areas of core habitat for important biodiversity elements, requires a sound understanding
of living requirements of important species and processes required to ensure the maintenance of
important ecosystems and habitats. This knowledge is typically only privy to a small number of
experts, which if not captured in a meaningful way would require specialist input wherever such
species were identified. Interpretation of living requirements amongst “experts” is also likely to vary,
which could lead to differences in approaches under different scenarios. Guidelines for identifying
and mapping such areas have therefore been included in information sheet templates. These must
be used to help identify areas of core habitat and to map out the area required to ensure that
species persistence is promoted. Where such information is not available, requirements will need to
be established through a literature review and through consultation with relevant specialists and
conservation agencies.
8.4. Adjust aquatic impact buffer
requirements based on sensitivities of any
important biota identified
Once core areas have been established, it is important to assess threats posed by planned
developments / activities on the species and associated core areas. The first step here is to re-
assess the sensitivity scores used to define aquatic impact buffer requirements for the water
resource. While aquatic impact buffers may be appropriate to reduce impacts to the functioning of
Core habitat: The area of natural habitat essential for the long-term persistence of a
species and processes in its current distribution range.
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the water resource, more stringent mitigation measures may be necessary based on the
susceptibility (sensitivity) of biodiversity elements to lateral impacts. For example, the sensitivity of
a floodplain system to sediment inputs may be low but an important population of endangered plant
species may occur down-slope of the proposed development which could potentially be significantly
impacted if stringent sediment control measures are not in put in place. In this case, the buffer zone
should be adjusted outwards to ensure appropriate protection of this plant community. This is
accounted for in the buffer zone tool by selecting a sensitivity class for biodiversity where this is
likely to be higher than that for the water resource (See Section 8.1). This refined sensitivity score
is then used to refine aquatic impact buffer requirements.
8.5. Identify any additional biodiversity
buffer requirements
While identification of areas of core habitat is necessary to ensure the persistence of important
biodiversity elements, these areas may be prone to disturbance and degradation from adjacent land
use / activities. Adjacent land use / activities could disrupt natural wildlife activities, such as feeding,
breeding and sleeping, or may affect habitat quality, adversely affecting their survival. The degree
to which wildlife are affected by disturbance is dependent upon many factors however, including
intensity of the disturbance, duration, species, and the life‐cycle stage of the species.
The ‘flushing’ of birds due to human presence is one example of the impact of disturbance on biota.
Such disturbance may cause birds to leave their nests, which can cause clutch failure or the
abandonment of the nest altogether, thereby reducing breeding success of the species. Much
research has been done on this aspect (Annexure 1) and this information should be consulted when
determining biodiversity buffers for species prone to noise and direct human disturbance.
There may therefore be a need to apply additional biodiversity buffers to important biodiversity
features including core areas and corridors to ensure that these areas continue to provide valuable
biodiversity functions. A working definition for biodiversity buffer zones, together with a description
of key functions that would be provided by such areas is included in Table 27.
Table 27. Description of key biodiversity buffer function
BUFFER
FUNCTION DESCRIPTION
Screening of
adjacent
disturbances
Anthropogenic disturbances to aquatic and semi-aquatic species may be direct, such as
human presence and traffic or indirect, such as through noise and light. These disrupt
natural wildlife activities, such as feeding, breeding and sleeping, or may affect habitat
quality, adversely affecting their survival. Biodiversity buffers can mitigate these impacts,
thereby maintaining values of important biodiversity features.
The width of the biodiversity buffer should be informed by the specific threats identified and the
sensitivity of the species or habitat to disturbance. In the case of species of conservation concern,
Biodiversity buffer zone: A buffer zone designed to adequately mitigate adverse
effects of adjacent land use activities on important biodiversity features.
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the need for additional biodiversity buffers should be informed by species information sheets where
available or with appropriate specialist input.
8.6. Assess the need for connectivity and
identify suitable fine-scale corridors where appropriate
In some instances, persistence of a species may be significantly improved by increasing the level of
connectivity between available patches of suitable habitat. Biodiversity corridors should therefore
be introduced where possible to increase the viability of species populations which are dependent
on dispersal between sub-population nodes for long-term persistence. A definition for biodiversity
corridors is included below together with a description of key functions that would be provided by
such areas (Table 28).
Table 28. Description of key biodiversity corridor function
BUFFER FUNCTION DESCRIPTION
Habitat connectivity Buffers along water resources provide potentially useful corridors, allowing the
connection of breeding, feeding and refuge sites crucial to maintain the viability of
populations of semi-aquatic species
The need for establishing biodiversity corridors will depend on characteristics of the species
concerned. As a result, the need for establishing such areas is included in species information
sheets, together with guidelines regarding the nature of such a corridor required to meet the needs
of the particular species concerned. A basic guideline document outlining guiding principles for
corridor design has also been developed to help guide assessors. This is included in Annexure 19
of this report.
Note: Provincial conservation bodies should be consulted to with regards local and landscape-level
corridors identified to maintain biological processes.
9. STEP 6: DELINEATE AND DEMARCATE
RECOMMENDED SETBACK REQUIREMENTS
Now that protection requirements for water resources and associated biodiversity have been
established, the next step is to finalize and delineate setback requirements on a layout plan and in
the field. In doing so, it is also important to ensure that setback requirements also cater for a range
of other potentially important management, functional and legal requirements.
Biodiversity corridor: Typically linear habitats that differ from a more extensive,
surrounding matrix, designed to link one or more patches of habitat to improve species
movement and dispersal.
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9.1. Delineate the boundary of water resources
Water resource boundaries must be mapped according to the guidelines provided in Section 5.1 of
this report. This area effectively represents the preliminary “no-go” area for development.
9.2. Map required for aquatic impact buffer zones
Once the starting point for mapping aquatic impact buffers has been delineated (See Section 5.3),
aquatic impact buffer requirements must be mapped to indicate the implications of buffer
requirements for development planning. In most cases, this will simply entail mapping the maximum
of buffers recommended for construction and operational phases. There may be instances however
where a narrower buffer is permissible during the construction phase (e.g. to account for sediment
risk associated with site clearing) and should be mapped separately from a larger operational buffer
(defining setback requirements for actual infrastructure).
In cases where the initial site-based buffer requirement has been refined through the identification
of additional mitigation measures, it is recommended that both the initial buffer and refined buffer
recommendations (with mitigation) are mapped.
The process of mapping is aided considerably through the use of GIS, which has tools to buffer
mapped features based on whatever width is specified. Where this is not available, the desktop
buffer zone line may be simply drawn on a 1:10 000 topographic map sheet or layout plan. It is
important to note here, that the calculated buffer widths are based on horizontal rather than a
diagonal distance as illustrated in Figure 13.
Figure 13. Cross-section through a slope adjacent a water resource indicating how buffer zone
widths should be measured.
9.3. Map setback requirements for water resource protection
It is important to note that setback requirements are dictated not only by requirements for minimizing
impacts of pollutants on the water resource. No development is typically permitted within the water
resource boundary. As a consequence, setback requirements are effectively determined by the
maximum distance of (i) the water resource boundary (including riparian habitat) or (ii) the aquatic
impact buffer zone required to protect the water resource. This is illustrated for a river and estuarine
system in Figures 14 and 15, below.
Buffer width

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Figure 14. Example 1: Map indicating the active channel, riparian zone, recommended aquatic
impact buffer zone and final recommended setback requirement for a proposed residential
development planned alongside a river system.
Figure 15. Example 2: Map indicating the edge of the supratidal zone, estuary boundary (5 m
AMSL), recommended aquatic impact buffer zone and final recommended setback requirement
for a proposed residential development planned alongside an estuarine system.
Legend
Supratidal zone
5 m AMSL
Aquatic impact buffer
Set-back requirement
Legend
Active Channel
Riparian Zone
Aquatic impact buffer
Set-back requirement

Preliminary Guideline for the Determination of Buffer Zones 2014
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9.4. Map zones for biodiversity protection
Once zones for biodiversity protection have been identified, these
must also be included on a map, together with the proposed layout
plan. This includes the extent of core areas, biodiversity buffers and proposed biodiversity
corridors.
9.5. Ensure that any additional factors have
been considered before finalizing setback
requirements
There may be a range of additional factors that have a bearing on where developments may take
place around targeted water resources. While considerations will vary from case to case, the
following key aspects should be considered:
• Hydrological buffers: Where there is a risk of planned developments having a negative
impact on groundwater, it may be necessary to establish hydrological buffers to reduce the
risk of drawdown or pollution of groundwater resources24. This is typically an important
consideration where mining operations pose a significant risk to groundwater resources.
Guidelines for determining this “hydrological buffer” or protection zone are included in the
Groundwater Resource Directed Measures (Parsons & Wentzel, 2007). Provision is also
made for determining protection zones to cater for anticipated impacts from on-site
sanitation that can affect water resource quality and cause health impacts to communities
(Parsons & Wentzel, 2007; Denise et al., 2013).
• Flood risk: Local policies may require flood lines to be determined which may impose
additional restrictions (other than those required to maintain water resource quality) to
minimize potential impacts associated with risks to water quality during flood events or
potential impacts on the welfare, health or safety of human beings or to property in the
downstream area. In other instances, local authorities may impose wider setback
requirements to provide “adjustment space” to cater for anticipated future flood risks.
• Aesthetic considerations: Buffer zones can screen undesirable views and so enhance
visual quality, appreciation and increase property values particularly in urban areas. There
may therefore be occasions where setback requirements are adjusted for aesthetic
purposes.
• Recreational use: The availability of open space associated with buffer zones provides
opportunities for a range of recreational activities. This is particularly important in urban
areas where availability of open space is often lacking.
Additional buffer zone guidelines may also be applicable for particular habitats. For example,
guidelines for forest buffers are contained within the draft Guidelines for Biodiversity Impact
Assessment in KZN (EKZNW, 2011). These guidelines recommend that buffer widths ranging from
20 m up to 200 m are established for different forest types (measured from the forest edge). In such
instances, setback requirements may need to be adjusted considerably from those initially identified.
24 Ramsar guidelines suggest that boreholes should not be located close to the wetland where the cone of depression
would reduce water levels in the wetland and cause degradation of ecological character (Ramsar Convention Secretariat,
2010).
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9.6. Map recommended setback requirement
based on the maximum width for water
resource, biodiversity protection and
additional considerations
Final recommended setback requirements should be delineated on the layout plan based on the
maximum widths required for water resource or biodiversity protection and any other local
considerations.
9.7. Finalize proposed setback requirements
with motivations for any deviations from
recommended requirements
There may be instances where strong motivations can be made for encroaching on recommended
setback areas. These could be linked to the management objectives of the water resource (See
Section 7.10) or may be linked directly to aspirations of a development proposal. Any plans of such
a nature should be appropriately assessed, motivated and indicated on a revised layout plan.
10. STEP 7: DOCUMENT MANAGEMENT MEASURES NECESSARY TO
MAINTAIN THE EFFECTIVENESS OF SETBACK AREAS
Once a setback area has been determined, appropriate management measures need to be
determined and documented accordingly. Key aspects of the setback requirements will include:
• An aquatic impact buffer zone;
• Possible core habitat requirements;
• Possible corridor requirements; and
• Any additional aspects requiring consideration to ensure effective management of setback
areas.
All of these aspects need to be taken into consideration when determining and documenting
management measures necessary to maintain or enhance the effectiveness of the setback area. To
do this, a buffer zone management plan is required. Management measures for each of the sections
of the buffer zone management plan are discussed in the sections below.
In addition to the key aspects that require management measures there are also a number of
additional aspects that may require consideration. For example, management measures for
potential additional mitigating measures that may be required to be considered before finalizing the
setback requirements (i.e. hydrological buffers, aesthetic considerations, recreational use, etc.).
Likewise, a range of other aspects associated with the effective management of setback areas may
Buffer Zone Management: The principle of buffer zone management is to ensure that
measures are tailored to address the relevant potential threats from the proposed
landuse / adjacent activity, while taking into consideration the site characteristics.
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also need to be considered (e.g. regulation requirements, demarcation, rehabilitation or
enhancement, etc.). A range of these aspects are discussed in Section 10.3.
10.1. Document management measures to
maintain or improve the functionality of
aquatic impact buffers
Once an aquatic impact buffer zone has been determined management measures need to be
tailored to ensure buffer zone functions are maintained to effectively mitigate the relevant threat/s.
Management measures must therefore be tailored to ensure that buffer zone functions are not
undermined. Aspects to consider include:
• Aquatic impact buffer zone management requirements;
• Management objectives for the aquatic impact buffer zone; and
• Management actions required to maintain or enhance the aquatic impact buffer zone in line
with the management objectives. Activities that should not be permitted in the aquatic impact
buffer zone should also be stipulated.
Based on a review of buffer attributes (Annexure 16), it is clear that the following characteristics are
particularly important in ensuring that aquatic impact buffer zones function effectively:
• The slope of the buffer;
• Vegetation characteristics (basal cover);
• Soil permeability; and
• The topography of the buffer zone.
Practically, this means that risks affecting vegetation, soil permeability (and infiltration) and buffer
topography (including erosion) must be managed to ensure that aquatic impact buffer functions are
retained or enhanced.
10.1.1. Buffer zone vegetation
Vegetation mechanically filters runoff, causing sediment to be deposited in the buffer zone. The
more suitable the vegetation is at slowing flows and encouraging infiltration, the more effective the
buffer zone is likely to be. Once infiltration has occurred, other plant characteristics affect the
amount of uptake of pollutants that can occur from the subsurface flow. Whilst simply maintaining
vegetation cover in the buffer zone should be a key management focus, some vegetation attributes
are particularly relevant in trapping or assimilating different pollutants:
• Sediment: Whilst the type of vegetation (grass vs forest) appears to have little bearing on
buffer zone effectiveness, the robustness and density of vegetation, is important since this
has a direct impact on flow rate, encouraging deposition of sediment. For this reason, buffer
zone effectiveness for sediment retention can be maximized by promoting good basal cover
and vegetation that is able to intercept water flow. The latter is particularly important in
situations where high runoff volumes are anticipated (e.g. in climates characterized by large,
intense rainfall events and sites with characteristically steep slopes and shallow or poorly
drained soils).
• Nutrients: Information in the literature suggests that species composition can affect the
ability of buffer zones to assimilate nitrate as can the productivity of buffer zone vegetation.
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Since phosphate is typically bound to sediment, vegetation attributes that promote sediment
retention are regarded as important in assimilating both these nutrients. Because of the
different modes of particulate and dissolved contaminant transport, multi-tier or combination
buffers may be most effective in assimilating nutrients in surface runoff.
• Toxins: Removal of organic pollutants and pesticides typically requires similar buffer
attributes as that for sediment retention. Likewise, removal of toxic metal contaminants
typically requires similar buffer attributes for assimilating nutrients in surface runoff.
• Pathogens: Removal of pathogenic micro-organisms typically requires similar buffer
attributes as that for sediment retention.
While there is some variability in the importance of different vegetation attributes in performing
different functions, it is clear that this has a critical role to play in ensuring that buffer functions are
maintained or enhanced. The key point to emphasize is that buffer zone vegetation must be
managed in a reasonable state to maintain effectiveness. For this reason, management measures
should be carefully documented to ensure that the site is not undermined by poor management or
undesirable activities within the buffer zone.
From a management perspective, there are a range of activities which need to be considered that
can negatively affect buffer zone vegetation. Typical threats to buffer zone vegetation that need to
be prevented by good management include:
• Overgrazing;
• Trampling by livestock;
• Transformation, e.g. new infrastructure;
• Alien plant encroachment; and
• Undesirable burning regimes.
While a range of site-specific mitigation measures may be relevant, the following generic
management measures are recommended to ensure that aquatic impact buffer zones continue to
function in a suitable manner:
• Demarcation in high risk areas (refer to Section 10.3.2);
• Suitable management of livestock and pedestrian traffic. For example:
o Grazing in riparian habitat should be avoided. Livestock generally cause damage to
the banks of rivers (from trampling) and the resulting erosion can be very difficult to
fix. If there are indications that an erosion problem is developing, an alternative may
be to pipe water to a point away from the stream/river (SANBI, 2013).
• To not allow infrastructure that permanently destroys buffer vegetation;
• Maintenance of natural fire regimes, where appropriate, to maintain indigenous vegetation
cover; and
• The application of appropriate alien plant control operations.
10.1.2. Soil characteristics
Whilst soil characteristics are determined by local geology, it is useful to understand what factors
affect the ability of the buffer zone to perform various functions:
• Sediment: Soil characteristics affect soil drainage which has a direct bearing on time taken
for soil saturation to occur and therefore surface runoff that carries soil particles. Soil texture
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reduced as it moves through the buffer zone. This is particularly true for finer clay particles,
as the more the water infiltrates the more fine sediment is trapped in the soil profile.
• Nutrients: The primary mechanism of phosphorous removal is co-deposition with
sediments. As such, buffer zone attributes that promote sediment retention are best suited
for phosphorous removal. The relationship between soil properties and nitrogen removal is
more complicated with coarse soils being well suited for the nutrient removal of sediments
attached nutrients while poorly drained soils, on the other hand, create favourable conditions
for de-nitrification, by promoting the formation of anaerobic conditions.
• Toxins: Refer to Section 10.1.1.
• Pathogens: The primary mechanism for the removal of micro-organisms in runoff is infiltration
(Tate et al., 2004). This is usually coupled with their adsorption to soil particles, hindering their
passage to the water body, resulting in their eventual death.
From a management perspective, there are a range of activities that can negatively affect buffer
zone soil characteristics which need to be considered. Typical threats to buffer zone soil
characteristics include:
• Soil compaction;
• Surface-water flows that create channels, which could lead to erosion25; and
• General physical disturbance to the soil profile.
10.1.3. Topography of the buffer zone
Topography has an influence on the rate at which runoff flows over the landscape. Uniform
topography with few areas where runoff can concentrate to form erosion gullies will lead to uniform
movement across the buffer zone. Where local topography concentrates flows and increases runoff
velocity, buffer zones are likely to be less effective. However, it is useful to understand what factors
affect the ability of the buffer zone to perform various functions:
• Sediment and nutrients: The effectiveness of a buffer at reducing sediment and nutrients
when flows become concentrated is reduced significantly. This suggests that buffer widths
need to be increased significantly where local topography encourages concentrated flows.
• Toxics: Refer to Section 10.1.1.
• Pathogens: Refer to Section 10.1.1.
10.2. Document management measures to
safeguard species and habitat over the long-
term
A review of international literature found that in general significantly larger buffers are required for
the protection of biodiversity that is dependent on water resources, in comparison to those adequate
for providing water quality protection (as illustrated in Figure 16). Many aquatic and semi-aquatic
faunal species depend upon water resources for only portions of their life cycles and they require
terrestrial habitats adjacent to the water resources to meet all their life needs. Without access to
25 Concentrated flow can undermine the effectiveness of buffer zones, leading to contamination of water resources
from adjacent land uses. As such, it is important that concentrated flows are minimised through appropriate on-site
management measures and that any erosion is quickly identified and addressed.
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appropriate terrestrial habitat and the opportunity to move safely between habitats across a
landscape, it will not be possible to maintain viable populations of many species. Therefore, core
habitats and corridors need to be developed for the protection of species or habitats of conservation
concern.
Figure 16. An illustration of the significant difference between biodiversity buffer requirements
and water quality protection requirements (Nichols et al., 2008).
Once protection zones for important biodiversity elements have been identified, the next step is to
define specific management measures to ensure these features persist over the long term. Here,
assessors are referred to information sheets for specific biodiversity features in which key
management considerations are identified (examples are included in Annexure 18). These should
be used to help develop appropriate management plans for the areas identified. Core habitat and
ecological corridor management plans should include:
• Establishing the management requirements for the core habitats and / or corridors;
• Determining management objectives; and
• Determining and documenting management actions required to maintain or enhance the
core habitats and corridors in line with the management objectives. In addition, activities that
should not be permitted in the core habitats and corridors should be noted.
10.2.1. Core habitat management
While determining the area and distribution of a core habitat is important, it is equally important that
appropriate management measures be determined to ensure the core habitat continues to function
effectively. Biodiversity conservation management measures that need to be taken into
consideration when determining management measures for core habitats and corridors include
(adapted from SANBI, 2013):
• Habitat and species management;
• Alien and invasive species management;
• Fire management;
• Grazing management; and
• The management of soil erosion and physical disturbances.
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In general, management measures aimed at maintaining natural disturbance regimes (e.g. grazing
and fire) and reducing impacts from disturbance (e.g. alien vegetation) are likely to contribute
meaningfully towards maintenance of habitat quality of a buffer zone. For example, the maintenance
of natural vegetation structure and composition would largely cater effectively for the needs of the
target species, for which the core habitat and corridor is required.
Note: Buffer averaging26 may also be a useful tool to ensure that important habitat attributes are
retained without unduly constraining development opportunities.
Management measures for biodiversity conservation will be dependent on the relevant species or
habitat requirements and therefore management measures will need to be determined on a site-by-
site basis. Guidelines on biodiversity conservation management are readily available in South Africa
and should be used to inform biodiversity conservation management within buffer areas. In addition,
it is important that the relevant conservation authorities be consulted with regards to the required
specific management measures for the species or habitat of concern (This is where the
recommended biodiversity information sheets in Annexure 18 would be particularly useful).
10.2.2. Ecological corridor design and management
Maintaining connectivity is another key consideration that can largely only be achieved through
broader landscape scale planning initiatives. While scientific literature indicates that corridors should
be hundreds of meters wide to provide functions over an extended period (Bennett, 2003) it may still
be beneficial to provide narrower corridors (Granger et al., 2005). Indeed, corridors as narrow as
30 m may have some wildlife and habitat value (Desbonnet et al., 1994). Design of such corridors
should however be undertaken with due consideration of particular species, particularly where rare,
threatened or endangered species are known to utilize the area. The seven step approach, as
described in Annexure 19, should be used as a guideline for ecological corridor design:
26 An example of buffer averaging (adapted from Nichols et al., 2008): A wetland requires a 30 m minimum buffer,
however, a 20 m buffer over part of its margin may be tolerated if a wider buffer is provided along another part. This
may depend upon such issues as water flow, topography, habitat and species needs, and other factors that can best be
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In addition, the following general recommendations for corridor management should be taken into
consideration (Fischer and Fischenich, 2000):
• Many semi-aquatic and aquatic species may at some stage of their life cycle need to use
corridors for habitat, movements, or dispersal. Therefore management of corridors should be
considered at a landscape level;
• Corridors that maintain or restore natural connectivity are better than those that link areas
historically unconnected;
• Continuous corridors are better than fragmented corridors;
• Wider corridors are better than narrow corridors;
• Riparian corridors are more valuable than other types of corridors because of habitat
heterogeneity, and the general availability of food and water;
• Several corridor connections are better than a single connection;
• Structurally diverse corridors are better than structurally simple corridors;
• Indigenous vegetation in corridors are better than non-indigenous vegetation; and
• Practical ecological management of corridors should mimic naturally occurring processes.
10.3. Additional aspects requiring consideration
to ensure effective management of setback areas
There are many aspects that need to be considered to ensure that, once
established, setback areas continue to provide their required functions. Overlooking these aspects,
discussed below, may result in the degradation of setback areas over time.
10.3.1.
Regulating aquatic impact buffer zones
The responsibility for managing or maintaining a buffer required to mitigate the impacts of an
adjacent land use / activity is suggested to be either the developers or the landowners. They will
Step 1 •Identify priority species requiring protection
Step
2 •Understand the biology of the priority species identified
Step
3
•Assess whether there are other viable patches in the surrounding landscape that support
priority species
Step
4•Identify focal species for further consideration
Step
5•Evaluate feasibility for implementing corridors
Step
6•Refine the list of focal species based on the availability of suitable corridor options
Step
7•Design the ecological corridor
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need to be responsible for ensuring that management measures required, both during the
construction and operation phases (and if necessary the decommissioning/ closure phase) of the
development, are implemented. To achieve this, buffer management measures should be included
in the Environmental Management Plan27 (EMP) for the proposed development.
10.3.2. Aquatic impact buffer zone demarcation
Clearly delineating and marking a buffer zone will help to ensure that it is not degraded over time
(Granger et al., 2005). Once a project has been approved, and prior to construction, the buffer
should be measured and clearly marked on the ground.
Granger et al. (2005) suggest that during the construction phase, constructing a temporary sediment
fence will help to ensure that the boundary is clearly demarcated. Likewise during the operational
phase, erection of a permanent fence may be desirable, particularly in an urban environment where
uncontrolled human access could result in trampling of vegetation and subsequent erosion. Active
exclusion may also be appropriate in intensive livestock operations where over-use could lead to a
reduction in vegetation condition and stream bank collapse. Where buffer zones are established
with a clear emphasis on biodiversity protection, fencing off the boundary may also be important to
reduce noise and light intrusion and to limit direct disturbance to wildlife.
Placement of signage along the boundary of the buffer zone should also be considered to help mark
the boundary and also help educate landowners / stakeholders about the purpose and value of
protecting buffer zones (Granger et al., 2005). In areas where there is the potential for human
disturbance and degradation of the buffer, more extensive signage explaining the value of the buffer
may be necessary to help develop support for protecting the buffer. In addition to signage, it may be
necessary to engage with stakeholders to explain the reasons why the buffer and the water
resource are protected and what human activities are allowed.
10.3.3. Aspects that may require the expansion of the aquatic
impact buffer zone
In documenting the management measures it is important to also consider additional aspects that
may require the buffer zone to be expanded further. For example:
• Fire breaks. These are particularly relevant in circumstances where buffer zone habitat is
prone to outside disturbance or requires regular fire management to maintain the vigour of
indigenous vegetation28.
• There may also be a strong motivation to establish a management buffer to prevent damage
to important intact areas such as intact indigenous riparian areas. Examples of where this
should be considered include:
27 An Environmental Management Plan (EMP) can be defined as “an environmental management tool used to ensure that undue or
reasonably avoidable adverse impacts of the construction, operation and decommissioning of a project are prevented; and that the
positive benefits of the projects are enhanced”. EMPs are therefore important tools for ensuring that the management actions
arising from Environmental Impact Assessment (EIA) processes are clearly defined and implemented through all phases of the
project life-cycle (Lochner, 2005).
28 This is typically the case in forestry areas where buffers need to be wide enough to facilitate burning without such
activities placing an unacceptable risk on plantation areas.

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o Forestry activities where felling of trees and other operational activities could damage
adjacent habitat29; and
o Industrial or similar activities where a physical barrier is required to limit the risk of
machinery impacting important conservation areas.
10.3.4. Maintenance of supporting mitigation measures
In many instances, aquatic impact buffer zones may be reduced based on a commitment to
implement effective alternative mitigation measures. It is therefore essential that these additional
mitigation measures are managed effectively to ensure that contaminant risk is minimized and that
erosion or smothering of buffer zone habitat does not take place. Specific requirements necessary
to ensure the ongoing functioning of these measures must therefore also be clearly documented in
environmental management plans / programmes and be enforced through regular monitoring.
10.3.5. Buffer zones in urban areas
According to Granger et al. (2005), a frequent concern about buffers is their applicability to urban
areas. The concerns generally fall into two categories:
• The science on buffers comes largely from sectors such as the agricultural and forestry
sector, and are therefore perceived to be irrelevant to urban areas; and
• The need to maximize density of development in urban areas is in direct conflict with the
protection of riparian and terrestrial habitat adjacent to water resources.
Granger et al. (2005) suggest that the concern over the relevancy of the literature on buffers to
urban areas is largely unfounded. Buffers do not function any differently in urban settings. The same
processes of sediment, nutrient, toxins, and pathogen removal operate similarly in urban areas as
they do in non-urban areas. In an urban setting it could be argued, for example, that a good storm
water management program could reduce the need for buffers to perform filtration functions to the
same level as those in non-urban areas. The role of buffers in providing needed habitat for aquatic,
semi-aquatic and terrestrial species, and in screening adjacent noise and light is also performed
similarly. In fact, a case can be made that buffers in urban areas are even more important from a
habitat perspective because there is little other habitat available. Factors that may differ in urban
areas are that urban water resources may perform some functions at a lower level because of
degradation, and that species diversity may be lower. However, remaining water resources in urban
areas may, in fact, function as habitat islands and be critical to many species (Granger et al., 2005).
Generally, the protection of habitat functions of water resources requires larger buffers than
29 Forestry South Africa Environmental Guidelines (Forestry South Africa, 2002) recommend that a buffer of at least 5
metres should not be planted around the edge of an indigenous forest (including riparian forest). This buffer should be
kept free of weeds and the indigenous vegetation which exists or regenerates must be protected. The guidelines further
recommend that where there is potential for damage during operational activities, the boundaries should be increased.
Once established, the guidelines suggest that no other activities or roads should be established in these buffer zones.
Note: In the case of intact indigenous riparian areas, where the setback requirement is
determined to be the edge of the riparian area, consideration of a ‘riparian edge management
buffer’ to protect the edge of the riparian area is advised (i.e. This would be in addition to the
aquatic impact buffer zone).

Preliminary Guideline for the Determination of Buffer Zones 2014
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protection of water quality functions. However, the best way to address the issue of buffers in urban
areas is to conduct an assessment of water resources at a landscape level, and develop a plan that
identifies, prioritizes and protects the most important water resources. In addition, the use of
relevant alternative mitigating measures might help to find a balance between development and the
protection of water resources.
10.3.6. Rehabilitation or enhancement of buffer zones
Existing or previous land use practices often impact / alter the terrestrial habitat adjacent to water
resources. These impacts generally include the clearing of vegetation, significant degradation of the
vegetation and soil, and / or the presence of alien invasive vegetation. In these situations, simply
providing a buffer with a set width is likely to fail to provide the necessary characteristics to protect a
water resource’s functions (Sheldon et al., 2005). Rehabilitation will therefore be required to restore
buffer functionality.
In other cases, a buffer zone may be in relatively good condition but still be sparsely vegetated with
trees and shrubs. In such cases, to ensure the relevant functions are provided, it may be desirable
to improve the screening and habitat value of the buffer by planting additional trees and shrubs or
other vegetation appropriate to the vegetation type for the ecoregion. Generally, for buffer zones to
function effectively they need to be well vegetated, and largely with indigenous vegetation (Sheldon
et al., 2005). This assumption should guide rehabilitation or enhancement of buffer zones.
In cases where the area available for a buffer may not be well vegetated, it may be necessary to
either increase the buffer width or require that the recommended buffer zone be rehabilitated. When
buffer rehabilitation is required, indigenous vegetation for the ecoregion of concern should be used
for re-vegetation purposes. Buffer rehabilitation will also require the same diligence as is prescribed
in wetland rehabilitation, and should therefore require monitoring to ensure success.
10.3.7. Buffer zones and climate change
The effects of climate change are likely to add to the challenges of managing aquatic resources and
therefore the development of setback areas should ideally cater for the potential impacts of climate
change. At best, a precautionary approach should be taken when determining setback
requirements, thus ensuring adequate measures are taken to address potential impacts resulting
from the effects of climate change.
Note: The relevant authorities should be consulted as to whether or not a developer / landowner
will be given the option of rehabilitating the recommended buffer or forego rehabilitation /
enhancement and allow a wider but poorly vegetated buffer (this allowance would not apply to
category 1 and 2 alien invasive plant species).

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11. STEP 8: MONITOR IMPLEMENTATION OF BUFFER ZONES
Monitoring the effectiveness of determined setback areas and the recommended management
measures for the relevant aspects of the setback area is vital for ensuring its effectiveness. In
keeping with the approach for determining and documenting management measures, monitoring
implementation should include:
• Determining monitoring objectives and indicators of buffer zone effectiveness; and
• Designing a monitoring program (e.g. timing, methods, etc.) for achieve the monitoring
objectives.
Monitoring implementation and management of the setback areas should be undertaken throughout
the duration of construction activities to ensure that the effectiveness of the setback areas are
maintained and that management measures are appropriately implemented. Regular inspections
during the operational phase should also be undertaken to ensure that functions are not being
undermined by inappropriate activities. Where relevant, inspections may also be required during the
closure phase.
In compliance with the requirements of an EMP the Environmental Officer and/or the Environmental
Control Officer should be checking that the following aspects are being effectively implemented:
• The setback area has been demarcated clearly;
• Disturbances are being managed effectively;
• Possible rehabilitation is being successfully implemented; and
• Required management measures are being effectively implemented.
Where concerns are noted, appropriate actions must be taken to ensure that the functions of
setback areas are not undermined. Key management aspects that will typically need to be
considered include:
• Use of setback areas and whether or not this is appropriately controlled to ensure that buffer
zone functions are not undermined;
• Maintenance of good vegetation cover through appropriate management measures (e.g.
burning, grazing, alien plant control, etc.);
A note on the use of the 100-year flood line: The 100-year flood line is considered to be the
minimum standard for flood management (Holmes and Dinicola 2010). Furthermore, it was
thought to represent an intermediate flooding level that would alert planners and property owners
to the effects of even greater floods (National Academies Keck Center 2004). However, the 100-
year flood line suffers from many drawbacks which limit its applicability: major differences in the
flood-height range between locations, lack of consideration of floods that exceed the standard
and lack of consideration of over-floodplain flow velocities (Holmes and Dinicola 2010). In light of
these limitations, and the expected increase in extreme flooding events under climate change
(Loukas et al., 2002; Nicholls 2004), a call for a higher standard seems to be inevitable. Already,
a simulation study has found that the 100-year flood line will likely be significantly reduced to
10-50 years because of the effects of climate change (Lehner et al., 2006).

Preliminary Guideline for the Determination of Buffer Zones 2014
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• Prevention of erosion and associated concentrated flows that may undermine buffer
functions; and
• Implementation of management controls necessary to ensure that corridors and core
habitats established for biodiversity are maintained.
In addition, where rehabilitation or some form of enhancement of a buffer is required, it is essential
that the maintenance of the buffer zone be monitored. A monitoring/maintenance program should
include evaluation of the rehabilitation measures and provide for alternative mitigation measures to
aid the buffer in achieving its required function. The developer or landowner should be responsible
for any maintenance or monitoring.
Likewise, it is also important to monitor buffer zones when human use is allowed or anticipated
(Granger et al., 2005). If monitored, adverse effects of human access such as vegetation trampling,
littering, and soil compaction or erosion, could be addressed before there is a negative impact on
the water resource. In some scenarios, it may also be appropriate to implement an ecological
monitoring programme to ensure that mitigation measures are effective at addressing potential
impacts to water resources. This is likely to be particularly important in high risk situations and
should be based on specialist input and input from regulating authorities.
Simply designating and marking the boundaries of buffer areas is not sufficient to protect buffers in
all cases. Regular observation of buffer areas is critical to determine whether vegetation and soils
are being damaged and to ensure that adjacent development does not encroach on the buffer over
time. Where illegal activities occur, enforcement actions to restore the buffer may be necessary.
The ‘final’ step in the approach to determining appropriate buffer zones focuses on providing
guidance on the need to monitor implementation and management of buffer zones once
established, to ensure that desired functions are achieved. In some instances, it may also be
necessary to review effectiveness of mitigation measures and apply adaptive management where
appropriate.
12. CONCLUSIONS AND RECOMMENDATIONS
The development of the preliminary guideline for determining buffer zones for rivers, wetlands and
estuaries required a comprehensive literature review to be undertaken at the onset of the project.
This provided the platform for the development of a conceptual framework to work within. Once the
framework was conceived the step-wise approach to determining buffer zones was developed. The
eight-step assessment procedure developed provides the user with a step-by-step approach to
determining appropriate buffer zones, or rather setback areas that take into consideration the
following:
• The aquatic impact buffer zone;
• Potential core habitats;
• Potential ecological corridors; and
• Possible additional aspects that will influence the final setback area or the management of
the setback area.
The assessment procedure detailed in this report, as well as the management practices that need to
be taken into consideration, provide the guidelines for determining and managing appropriate buffer

Preliminary Guideline for the Determination of Buffer Zones 2014
73
zones. The ‘Buffer Zone Tools’ developed in conjunction with this report provide the user with the
primary tool for determining appropriate buffer zones (included on the accompanying CD). In
addition, the extensive supporting documents provided as annexures to the report, either in
hardcopy or as electronic copies on the accompanying CD, provide extensive background
information.
While a sound scientific approach was adopted for the development of the preliminary guideline for
determining buffer zones, a number of assumptions and limitations were identified, these included:
• Whilst the threat assessment was informed by readily available scientific literature, there was
limited information available for some sub-sectors. As such, threat ratings should be seen
as preliminary and subject to further verification. This has been catered for t in the ‘Buffer
Zone Tools’ by making provision for specialists to review the preliminary threat ratings.
• Rule curves developed to inform buffer requirements were developed based on
interpretation of best available science at the time of the assessment. It is however
important to note that there was high variability in reported buffer efficiencies for different
contaminants and therefore these rule curves should be seen as an initial approximation.
These should be reviewed and refined in time to cater for more up-to-date information.
• Whilst minimum buffer requirements have been recommended to address some risks
associated with modelled outcomes and management risks, it is essential that such buffer
zones be appropriately managed to maintain their effectiveness. If this is not done, there is
a real risk that buffer zones will not perform functions in line with expectations.
• Whilst testing of the ‘Buffer Zone Tools’ was undertaken as part of this project, the tools
have subsequently been updated following feedback from the project team and steering
committee members. There is therefore a risk that some errors may be present in the buffer
zone tools. It is hoped that any teething problems will removed during further testing of the
preliminary versions.
• We recognize that biodiversity considerations are largely dependent on species information
sheets being developed. While some examples have been compiled as part of this project,
these should be viewed as preliminary and subject to further specialist input. It is hoped that
conservation agencies will take up the challenge to develop information sheets for priority
species to better inform protection requirements.
The decision to only release a preliminary guideline for buffer zone determination was because the
project team and the WRC steering committee agreed that a second phase to the project will be
required. The primary objective for a second phase would be to provide practitioners, i.e. specialists,
authorities and key stakeholders, with an opportunity to learn how to use the ‘Buffer Zone Tools’
developed. It is envisaged that a series of national training and development workshops will be held
to firstly train participants, and secondly obtain feedback from users to further refine the guideline
document and ‘Buffer Tools’. In following this approach there may also be an opportunity in the
future to incorporate additional aspects, for example the inclusion of possible buffer requirements to
mitigate issues such as groundwater and / or airborne contaminants.
Hopefully, the preliminary guideline for the determination of buffers for rivers, wetlands and
estuaries provides the initial tools to meet the demand for a scientifically defensible approach to
determining buffer zones. Furthermore it is hoped that over time (i.e. a second phase to the project)
there will an opportunity to refine the preliminary guideline document and buffer zone tools.

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establishment and maintenance. Maryland Cooperative Extension, Baltimore, Maryland.
Todd, A.H. (2000). Making decisions about riparian buffer width. In: Wigington, P.J, Bestcha, R.L.
(eds). Riparian ecology and management in multi land-use watersheds. American Water Resources
Association, Middleburg, VA.
Turpie, J.K., Clark B.M. (2007). The health status, conservation importance, and economic value of
temperate South African estuaries and development of a regional conservation plan. Report to
Cape Nature by Anchor Environmental Consultants. Report No. AEC2007/05.
Turpie, J.K., Wilson, G., van Niekerk, L. (2012). National Biodiversity Assessment 2011: National
Estuary Biodiversity Plan for South Africa. Anchor Environmental Consultants Report No
AEC2012/01, Cape Town. Report produced for the Council for Scientific and Industrial Research
and the South African National Biodiversity Institute.
van Niekerk, L., Turpie, J.K. (eds) (2011). South African National Biodiversity Assessment 2011:
Technical Report. Volume 3: Estuary Component. Pretoria: South African National Biodiversity
Institute. CSIR Report CSIR/NRE/ECOS/ER/2011/0045/B. Stellenbosch: Council for Scientific and
Industrial Research.
Wegner, S. (1999). A review of the scientific literature on riparian buffer width, extent and
vegetation. Institute of Ecology, University of Georgia.
Woodward, S. E., Rock, C. A. (1995). Control of residential stormwater by natural by natural
buffer strips. Lake and Reservoir Management 11, 37-45.

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Young, R. A., Huntrods, T., Anderson, W. (1980). Effectiveness of vegetated buffer strips in
controlling pollution from feedlot runoff. Journal of Environmental Quality 9, 438-497.

Preliminary Guideline for the Determination of Buffer Zones 2014
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14. ANNEXURES
Annexure 1 – Deliverable 1: Literature review (electronic copy only – refer to the CD provided)
Annexure 2 – Deliverable 11: Practical testing (electronic copy only – refer to the CD provided)
Annexure 3 – Range of management measures available to address threats posed to water resources
Note – Areas where buffer zones may apply a meaningful role in addressing potential threats are highlighted in blue.
THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
Changing the amount of water
(increasing or decreasing the
amount)
Upstream catchment • Direct abstraction
• Abstraction from groundwater
• Impoundments and associated increased
evaporation losses
• Stream flow reduction activities
• Invasion by woody alien invasive plants
• Inter-basin transfers
• Licensing of water use (including groundwater
abstraction)
• Protection of groundwater reserves
• Reserve determination
• Water resource classification
• Setting and monitoring of Resource Quality
Objectives
• Alien plant control activities
Adjacent land use • Abstraction from groundwater lowering water
levels
• Stream flow reduction activities
• Invasion by woody alien invasive plants
• Discharge of water from outside catchment (e.g.
grey water from municipal supply)
• Diversion of water away from water resource (e.g.
irrigation)
• Limiting impacts to preferential recharge areas
• Restriction of SFR activities (including
maintenance of buffer zones)
• Alien plant control activities
• Preventing diversion of water
Within water resource • Direct abstraction from water resource
• SFR activities in the water resource
• Invasion by woody alien invasive plants
• Extra water into the water resource
• Management of abstraction
• Restriction / removal of SFR activities
• Alien plant control activities
• Management of point discharges
Changing the fluctuation of
water levels (frequency,
Upstream catchment • Impoundments upstream of water resource
• Inter-basin transfers
• Development leading to hardened surfaces in
• Management of releases from impoundments
(allowance for natural floods)
• Stormwater detention and treatment

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
amplitude, direction of flow) catchment
• Poor land management leading to reduced basal
cover
• Sound land management practices
Adjacent land use • Hardened surfaces leading to increased runoff
intensity
• Storm water drains and associated discharge
• Storm water detention and treatment
• Prevention of canalized flows
• Buffer zones to mitigate diffuse flows
Within water resource • Development within water resources
• Drainage to minimize flooding
• Impeding features redirecting flows
• Alteration of surface characteristics (roughness)
• Direct water losses
• Impoundments causing flooding
• Control of activities directly impacting on water
resources
• Blockage of drainage channels
• Demolition of impeding features
• Rehabilitation / restoration of vegetative cover
• Management of on-site water use
• Decommissioning of impoundments
Changing the amount of
sediment entering water
resource and associated
change in turbidity (increasing
or decreasing the amount)
Upstream catchment • Impoundments upstream of water resource
(sediment trapping)
• Breaching of dams (scouring)
• Poor land use management (increased sediment
supply)
• Changes in water inputs resulting in elevated
flows and associated erosion
• Road infrastructure (density and management)
• Mining operations (e.g. coal and gold mines)
• Sound land management practices
• Management of road infrastructure
• Dam construction techniques (dam safety)
• Implementation of buffers at a catchment-
scale to reduce sediment inputs
Adjacent land use • Bulk earthwork activities
• Disturbance of soil surface
• Disturbance of slopes through creation of roads
and tracks
• Poor land management
• Inappropriate burning
•
• Changes in runoff characteristics
• Implementation of best-management practices
o Roads and associated drainage
o Earthwork activities
o Fire and livestock management
o Agricultural activities
• Source-directed controls
• Buffer zones to trap sediments
Within water resource
(geomorphology)
• Channel straightening (reducing flooding)
• Artificial infilling (affecting water distribution)
• Erosion (e.g. gully formation, bank collapse)
• Peat extraction
• Active rehabilitation
• Management of sediment removal activities
(permits)

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
• Sand winning
• Dredging
• Clearing of natural vegetation up to stream banks
• Stock-trampling and overgrazing
Alteration of water quality –
increasing the amounts of
nutrients (phosphate, nitrite,
nitrate)
Upstream catchment • Disposal or discharge of human (including
partially treated and untreated sewage) and
animal debris and excrement into water resources
• Runoff from agricultural activities such as the
large-scale concentration of livestock (feedlots)
• Over-use of nitrate-based fertiliser, for example
KAN, LAN, etc.
• Orthophosphates applied to agricultural or
residential lands as fertilizers and carried into the
surface water during storm events
• Activities that influence the oxidising or reducing
circumstances in the Nitrogen-cycle, such as
aeration or acidification
• Activities that disturbs bedrock which is high in
elemental nitrogen (N) such as excavation,
ploughing, building, and mining (Bossman et al.,
200930)
• Runoff from land areas being mined for
phosphate deposits
• Industrial discharges (e.g. sugar & dairy
industries)
• Elevated phosphorous levels in urban sewage
from use of household products, such as
toothpaste, detergents, pharmaceuticals, and
food-treating compounds
• Runoff / leachate from solid waste disposal sites
• Licensing of water use (including point-source
discharges)
• Provision of sanitation facilities
• Management of waste-water facilities
• Source-directed controls for agricultural
activities
• Management of mining activities
• Implementation of buffers at a catchment-
scale to reduce water quality impacts
Adjacent land use • As above • Rehabilitation / maintenance of riparian zone
30 Bossman, B.P., Nyman, A.J., Klerks, P.L. (2009). Relationship between hydrocarbon measurements and toxicity to a chirinomid, fish larvae, and daphnid for oils and oil spill
chemical treatments in laboratory freshwater marsh microcosms. Environmental Pollution 129, 345-353.

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
• Establishment of buffer zones to reduce
nutrient inputs in diffuse flow
• Implementation of appropriate stormwater
management around the excavation to prevent
the ingress of run-off into the excavation. This
will reduce the volume of pit water that is
contaminated with nitrate, which would reduce
the costs associated with the management of
this water.
• Implementation of appropriate stormwater
management around rock dumps through the
establishment of a clean and dirty water system,
which would reduce the volume of run-off
contaminated with nitrate from the rock dumps.
• Implementation of appropriate containment
measures for all impoundments used to store
contaminated water, such as pollution control
dams, return water dams and tailings dams,
such as clay and plastic linings
Within water resource • Defecation by livestock
• Point-source discharges of waste water
• Management of livestock
• Source directed controls
Alteration of water quality –
toxic contaminants (including
toxic metal ions (e.g. copper,
lead, zinc), toxic organic
substances (reduces oxygen),
hydrocarbons and pesticides)
Upstream catchment Toxic metal ions
• Mining operations, leading to the release of toxic
metal ions
• Purification of metals, e.g., the smelting of copper
and the preparation of nuclear fuels
• Industrial discharge (e.g. electro-plating, tanning,
smelting activities)
• Urban runoff containing lead from road surfaces
Toxic metal ions
• Mining: Implementation of appropriate
containment measures for all impoundments
used to store contaminated water, such as
pollution control dams, return water dams and
tailings dams, such as clay and plastic linings
• Control of waste discharges
• Guidelines for implementing Clean Technologies
• Environmental management systems (such as
ISO14001), which seek continuous improvement
in environmental management.
Toxic organic substances

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
Toxic organic substances
• Spray drift from pesticides
• Runoff of pesticides from agricultural lands
• Careless disposal of pesticide containers
• Release of household pesticides.
• Discharge of solvents, and other industrial
chemicals
• Discharge of pharmaceuticals and personal care
products through excretion or disposal by flushing.
• Control of pesticide application, particularly in
proximity to water resources
Adjacent land use As above • As above
• Maintenance of riparian zones
• Establishment of buffer zones
(especially wooded areas) to catch spray
drift and trap sediments with associated
toxics
Alteration of water quality –
acidity (pH) Upstream catchment • Acid mine drainage (AMD), or acid rock drainage
(ARD), from abandoned and active metal mines
or coal mines
• Runoff from coal stocks, coal handling facilities,
coal washers, and coal waste tips
• Controlled placement of overburden or
management of water to prevent AMD (involves
methods to minimize or neutralize the formation
of AMD. According to the generally accepted
chemical equations for pyrite oxidation, oxygen
and water are necessary to initiate acid
formation. Exclusion of either reactant should
preclude or inhibit acid production)
• Limestone chips may be introduced into sites to
have a neutralizing effect.
• Constructed wetlands to filter out heavy metals
and raise pH
Adjacent land use • As Above • AS above
Alteration of water quality –
concentration of salts
(salinization)
Upstream catchment • Return flows from irrigated croplands
• Fertilizers and biocides applied to agricultural
croplands
• Control of water use and point source
discharges

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
• Mine drainage (e.g. coal & gold mines)
• Point-source releases of salts from industrial
plants (e.g. Tanneries)
Alteration of water quality –
temperature
Upstream catchment • Overflow or release from impoundments
• Release / discharge from industries
• Design of overflow structures
• Control of point-source discharges
Adjacent land use • Removal / damage to riparian zone, important for
shading
• Release / discharge from industries
• Runoff from hardened surfaces
• Protection / re-establishment of riparian zone
to shade water resource
• Establishment of buffer zones to allow cooling of
water before entering water resources
Alteration of water quality –
pathogens (.e. disease-causing
organisms)
Upstream catchment • Wash from animal feeding operations
• Release from municipal wastewater treatment
plant effluents
• Discharge of partially treated sewage from
malfunctioning on-site systems (e.g. septic tanks),
• Treated sewage sludge (bio-solids) for crop and
landscape irrigation.
• Application of untreated manure as fertilizer on
agricultural lands
• Placement and management of animal feeding
areas
• Implementation of microbial standards for
reclaimed wastewater
• Implementation of best-practice guidelines for
construction of waste water systems
• Composting of manure to effectively eliminate
pathogens
Adjacent land use • Wash from animal feeding operations
• Discharge of partially treated sewage from
malfunctioning on-site systems (e.g. septic tanks),
• Treated sewage sludge (bio-solids) for crop and
landscape irrigation.
• Application of untreated manure as fertilizer on
agricultural lands
• Placement and management of animal
feeding areas
• Implementation of microbial standards for
reclaimed wastewater
• Implementation of best-practice guidelines for
construction of waste water systems
• Composting of manure to effectively eliminate
pathogens
• Establishment of buffer zones to help trap
pathogens before reaching water resource
Within water resource • Drainage inflows eliminated or managed
Changing the physical
structure within a water
resource (habitat)
Upstream catchment • Alteration of hydrological regime
• Alteration in sediment regime
• Alteration of water quality
• See relevant sections
Adjacent land use • Encroachment to achieve maximum commercial
returns
• Delineation and protection of water resource
• Establishment of buffer zones to limit

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THREAT LOCATION OF
THREAT SOURCE OF THREAT PRIMARY MANAGEMENT MEASURES
• Loss of fringing vegetation and erosion from stock
trampling
• Loss of fringing vegetation to provide aesthetic
views
• Alteration in natural fire regimes
• Shading of natural vegetation
disturbance
• Weed control in buffer zone
• Barriers to prevent trampling / damage to buffer
zone
• Introduction of fire break & appropriate burning
regime
Within water resource • Infrastructure development (e.g. housing, bridges,
etc.)
• Canalization or diversion of watercourses
• Mining within water resources
• Inundation by impoundments
• Cropping & pastures
• Encroachment by alien invasive plants
• Overgrazing and trampling by livestock
• Sports fields & gardens
• Seepage below dams
• Alteration in natural fire regimes
• Restricting developments with direct impact on
water resources
• Removing of crops and pastures & associate re-
vegetation
• Alien invasive plant control within water
resource
• Control of livestock numbers
• Introduction of fire break & appropriate burning
regime
Other disturbances Adjacent land use • Noise from urban areas and transportation
networks
• Light pollution from residential / industrial
developments
• Physical disturbance through hunting or
recreational activities
• Dust pollution from exposed areas, active
earthworks and dirt roads
• Restrict development away from water
resources with threatened species sensitive to
disturbance
• Construction of barriers (including buffers)
to reduce disturbance
• Use fencing or other means to control access
• Use best management practices to control dust
Within water resource • Physical disturbance through direct human
presence
• Restrict access, particularly where sensitive
species occur

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Annexure 4 – National and/or sub-national (CAPE) priority estuaries
(electronic copy only – refer to the CD provided)
Annexure 5 – Estuary importance scores for all South African estuaries
(electronic copy only – refer to the CD provided)

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Annexure 6 – Description of sectors and sub-sectors included in the threat assessment
SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Agriculture
Agricultural-based land-use
activities that range from the
large-scale commercial
production of crops and
timber to small-scale
subsistence crop farming
and livestock rearing. May
be associated with rural
and/or urban contexts.
Forestry/timber Includes the planting and harvesting of various species of non-
indigenous trees (pine, wattle, gum) but also includes
intensive planting and harvesting of indigenous species.
Nurseries and tunnel farming
operations
Intensive agricultural activities, associated with the production
of flowers, vegetables or other plant materials (e.g. flower
farms and crops in tunnels).
Dryland commercial cropland
– Annual rotation
The agricultural production of produce including crops,
vegetables or other plant material using conventional tillage
cultivation with no irrigation and requiring annual re-
establishment.
Dryland commercial cropland
– infrequent rotation
The agricultural production of produce including crops, trees,
seeds, fruit, or other plant material using conventional tillage
cultivation with no irrigation. Re-establishment takes place on
a bi-annual or more infrequent basis.
Irrigated commercial cropland The agricultural production of produce including crops, trees,
seeds, fruit, vegetables or other plant material using
conventional means of irrigation.
Subsistence cultivation
Communal land used for the cultivation of crops and for
livestock grazing activities. Typically involves less intensive
use of machinery, with lower nutrient and fertilizer inputs than
commercial operations.
Extensive livestock grazing
operations
Includes the rearing and husbandry of a range of domestic
livestock (e.g. cattle, sheep, horses, goats) on areas of natural
or largely natural pastures without irrigation.
Intensive livestock grazing
operations
Includes the rearing and husbandry of a range of
domesticated livestock (e.g. cattle, sheep, horses, goats) on
enhanced pastures, typically supplemented with irrigation.

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Concentrated livestock
operations
Livestock intensive operations associated with areas of
concentrated animal activities including (1) Dairies; (2)
Piggeries; (3) Poultry Facilities; (4) Stables, (5) Sale yards (6)
Feedlots and (7) Zoos.
Sludge dams associated with
concentrated livestock
operations
Sludge dams containing waste water from intensive livestock
operations.
Aquaculture or marine culture
Commercial production including the breeding, hatching,
rearing or cultivation of marine, estuarine or freshwater
organisms, including aquatic plants or animals (such as fin
fish, crustaceans, molluscs or other aquatic invertebrates but
not including oysters).
Industry
Includes a range of industrial
activities from light industrial
with limited impacts on
surrounding land use, to
hazardous or noxious
industry with high impact on
surrounding land use.
Includes activities such as
the processing of resources
and storage of manufactured
materials and products.
High-risk Chemical industries
Industries that produce/manufacture batteries (acid and
alkaline), paint solvents, petrochemicals, explosives,
radioactive materials, pharmaceuticals, pesticides, herbicides,
fungicides, rodenticides, nematocides, miticides, fumigants
and related products.
Chemical storage facilities Includes facilities to store or package chemical substances in
containers, bulk storage facilities, stockpiles or dumps.
Drum/container reconditioning
Industries that recondition and package containers (including
metal, plastic or glass drums, bottles or cylinders) previously
used for the transport of storage or substances classified as
poisonous or radioactive.
Paper, pulp or pulp products
industries Industries that manufacture paper, pulp or pulp-related
products.
Petroleum works
Industries that: (1) refine crude petroleum, shale oil or natural
gas; (2) Manufacture petroleum products (including aviation
fuel, petrol, kerosene, mineral turpentine, fuel oils, lubricants,
wax, bitumen, liquefied gas and the precursors to
petrochemicals, such as acetylene, ethylene, toluene and
xylene); or (3) Dispose of oil waste or petroleum waste or
process or recover oil waste or petroleum.
Breweries/distilleries Industries responsible for the production of alcohol-based

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
products such as ethanol and beer.
Cement/concrete works
Industries involved in the production of quicklime including the
use of argillaceous and calcareous materials in the production
of cement clinker. Includes the production of pre-mixed
concrete or concrete products.
Ceramic works Industries responsible for the production of products such as
bricks, tiles, pipes, pottery goods, refractories or glass
manufactured through a firing process.
Medium-risk Chemical
industries
Including the production of (1) agricultural fertiliser; (2) carbon
black industries, (3) explosive or pyrotechnics (for purposes
including extractive industries and mining uses, ammunition,
fireworks or fuel propellants); (4) paints, pigments, dyes,
printing inks, industrial polishes, adhesives or sealants; (5)
soap or detergent industries (including domestic, institutional
or industrial soaps or detergents); (6)plastics and (7) rubber
products.
Dredging works Storage and processing of materials obtained from the bed,
banks or foreshores of many waters.
Electricity generation works Facilities that supply electrical power from energy sources
(including coal, gas, bio-material or hydro-electric stations),
but not including solar powered generators.
Timber milling or processing
works
(Other than a joinery, builders’ supply yard or home
improvement centre) that saw, machine, mill, chip, pulp or
compress timber or wood
Livestock processing
operations
Processing of livestock including: (1) Slaughter animals
(including
poultry, piggeries, cattle and sheep)
Industries processing
livestock derived products
Industries involved with secondary processing of products
derived from the slaughter of animals (including tanneries,
fellmongeries, rendering or fat extraction plants, wool or
fleeces with an intended production capacity.
Composting facilities Facilities for the production of compost/manure originating
from livestock waste.

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Mixed-
use/Commercial/Retail/Business
Land use activities including
retail, commercial and
business with varying
degrees of mix.
Core Mixed-use
Intended for the development of the major activity focus or foci
of urban areas and provides for land and buildings where the
full range of residential, businesses, offices, service and light
industry, civic and social, educational and environmental uses
are freely permitted and under certain conditions general
industry is permitted but excludes extractive or noxious
industry.
Medium Impact Mixed-use
A mixed-use area where the full range of residential,
businesses, offices, service and light industries, civic and
social, educational and environmental uses are freely
permitted but excludes other forms of industry.
Low Impact Mixed-use
Includes areas where a full range of residential, businesses,
offices, civic and social, educational and environmental uses
are freely permitted, and under certain conditions light industry
might be permitted but excludes other industrial uses, and
which can act as an interface between residential and higher
impact non-residential uses or major traffic routes. The
general level of amenity is intended to be good.
Multi-Purpose Retail and
Office
Land use that provides for the development of a full range of
shopping centre types and can comprise a mix of retail, office,
residential and entertainment uses. Examples include:
Commercial/ Business; Hawking/Informal Trading; Laundrette;
Parking Garage; Restaurant ; Shop; Spaza; Take Away/Fast
Food; Tavern/Bar.
Petrol station / Fuel depot Land designated for buildings used for the sale of motor fuels,
lubricants, motor spares and motor accessories.
Maintenance and repair
facilities Facilities for the repair and maintenance of vessels, vehicles
or other machinery. Includes workshops, service yards, etc.
Offices
This includes all office development as the primary
developmental focus in suburban and peripheral locations,
adjacent to shopping centres or a mixed-use core, or as
independent zones. Forms of office development may include:
Doctor’s Consulting Rooms; Home Business; Office Building;
Private Clinic; Professional Office.

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Civic and Social
This category includes
buildings and land
associated with public and
private service providers and
administrative or
government functions
including education, health,
pension offices, museums,
libraries, correctional
facilities and community
halls.
Government and municipal Buildings to be used for National, Provincial and Municipal
administration and services.
Place of worship Buildings or portion of a building to be used as a church,
chapel, oratory, synagogue, mosque, and temple.
Education Educational facilities, including infants, pre-primary, primary,
secondary, tertiary and adult education and training with
associated buildings.
Cemetery Land used for public and private cemeteries, memorial parks,
funeral chapel and crematoria.
Health and Welfare Buildings for public and private hospital, medical centres,
clinics, sanatoria, community care, welfare and social
requirements.
Residential
Provides for land and
buildings for a variety of
housing types, ranging from
areas that are almost
entirely residential to those
areas having a mix of other
compatible land uses, where
the predominant land use is
residential.
Residential Low impact /
Residential only
Includes buildings for a variety of housing types with a limited
number of compatible ancillary land uses permissible so as to
cater for every day needs of the residents. The building
density is likely to be low (<1unit/acre) and the amenity high,
and generally in harmony with the natural environment.
Residential Medium Impact
Buildings for primary residential land uses with an increasing
number of appropriate ancillary land uses to satisfy local
demands and convenience. The residential density may also
increase which will increase the impact of the residential land
use on the area. Housing density of <1unit/acre: Includes
tourism cottage settlements, smaller cluster complexes, family
hotels, B&B Lodges.
High density urban –
Residential High Impact
Comprises the full range of residential accommodation and a
wide variety of services and activity mix to cater for broader
community needs. The residential density is likely to be higher
(>1unit/acre) thus increasing the impact of the residential use
on the area and requiring additional retail, civic and social and
service activity to serve the needs of the community.
Resort Accommodation in the form of lodges, bush camps, cultural
villages and bed and breakfast establishments within a rural
setting.

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Hotel The development of a licensed hotel. Accommodation and
public lounge and bar areas may be provided as well as other
recreational facilities and parking.
Informal settlements Housing density of >1unit/acre: intensive rural housing
development such as formal/informal settlements.
Open space
Areas defined as open
space include a range of
land-uses with minimal
infrastructural development,
such as parks, gardens and
off-road trails. Includes
areas set aside for
preservation and
conservation because they
provide ecosystem services,
are unique natural
landscapes, viewpoints,
areas of ecological, historical
and/or cultural importance,
bio-diversity, and/or have
unique, rare or endangered
habitats or species.
Parks and gardens
Land which is either publicly or privately owned/managed as
part of the sustainable open space system and the local
authority’s environmental services. It includes independent or
linked open space areas and green lung areas such as parks,
lawns and gardens for sporting and recreational activities.
Sports fields Land which is typically grassed and regularly maintained for
sporting activities.
Golf courses – fairways The part of a golf course covered with short grass and
extending from the tee to the putting green and maintained
through regular mowing.
Golf courses – tee boxes and
putting greens
Small areas of a golf course with very short grass that are
heavily manicured to maintain the condition of the grass
surface.
Maintained lawns and gardens Areas of lawn and gardens of introduced species, typically
requiring maintenance (fertilization, and / or irrigation).
Transportation infrastructure
Land used to provide for
developments and buildings
associated with public and
private transportation in all
its forms.
Paved roads
Land that has been provided for the full range of road
infrastructures within rural and urban areas. Roads that have
been paved/asphalted (includes major roads and freeways, as
well as bridges over waterways).
Unpaved roads
Land that has been provided for the full range of road
infrastructures mainly within rural areas. Including dirt tracks
and gravel roads that have not been formerly paved /
asphalted.
Paved trails Small trails that have been constructed by paving/asphalting.
Unpaved tracks and trails Unpaved tracks and trails used for recreational purposes (e.g.
biking/jogging)
Parking lots Extensively asphalted/paved areas used for the parking of
vehicles.

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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Airport – runways and
taxiways
Tarred runways and taxiways associated with private and
commercial airports used by various forms of commercial and
private aircraft.
Railway
Commuter, passenger and goods railway infrastructure within
the rural and urban context. Activities include one or more of
the following: installation of track; on-site repair of track; onsite
maintenance of track; on-site upgrading of track; construction
or significant alterations; operation of rolling stock on track.
Service infrastructure
Land use relating to the
provision of all necessary
utility services such as
communication, municipal
waste handling facilities and
associated transfer pipeline
infrastructure for fuels and
water.
Above-ground
communication/power
(electricity) infrastructure
Above-ground infrastructure designed for the transfer of power
(electricity cables) or data (telephone lines).
Below-ground
communication/power
(electricity) infrastructure
Below-ground infrastructure designed for the transfer of power
(electricity cables) or data (underground data cables).
Hazardous waste disposal
facility
Facilities for the disposal of Hazardous Waste, as analysed
and characterised according to SABS Code 0228, the Basel
Convention and Appendix 9.2 “Hazardous Waste
Classification Tables”, of the Department of Water Affairs and
Forestry’s Minimum Requirements for the Handling,
Classification and Disposal of Hazardous Waste. Material with
a Hazard Rating 1 (extreme risk) or Hazard Rating 2 (high
risk) can only be disposed of at a permitted landfill with an H:H
classification.
General solid waste disposal
facility
Facilities such as landfills for the disposal of household waste,
builder’s rubble and industrial waste that is not classified as
hazardous.
Sewage treatment works Treatment works and associated infrastructure including
pumping stations, sewage overflow structures and the

Preliminary Guideline for the Determination of Buffer Zones 2014
96
SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
reticulation system.
Septic tanks and french drains Septic tank and french drains used in residential areas for the
bacterial treatment and distribution of waste water.
Sludge dams associated with
concentrated livestock
operations
Sludge dams containing waste water from intensive livestock
operations.
Pipelines for transportation of
hazardous substances Pipelines (above or underground) for the transportation of
fuels and related chemicals.
Pipelines for the
transportation of waste water Pipelines for the transportation of waste water (e.g. sewage) to
treatment facilities.
Mining
This class comprises all
mining-related activities
including surface and sub-
surface mining, quarrying
and dredging for the
extraction of minerals or
materials, including sand
and stone.
Prospecting (all materials) Prospecting activities including excavation of test-pits
High-risk mining operations
Mining operations (including mine and mine waste) posing a
high water quality risk to water resources including mining of
the following substances: Antimony (Large mines), Asbestos,
Base metals (Copper Cadmium, Cobalt, Iron ore,
Molybdenum, Nickel, Tin, Vanadium) – sulphide ore, Coal,
Gold, silver, uranium.
Moderate-risk mining
operations
Mining operations (including mine and mine waste) posing a
high moderate risk to water resources. Includes underground
mining of the following substances: Antimony (Small mines),
Base metals (Copper Cadmium, Cobalt, Iron ore,
Molybdenum, Nickel, Tin, Vanadium) – oxide ore, Chrome,
Diamonds and precious stones, Phosphate, Platinum,
Magnesium, Manganese, Mineral sands (Ilmenite, Titanium,
Rutile, Zircon), Zinc and Lead, Industrial Minerals (Andalusite,
Barite, Bauxite, Cryolite, Fluorspar)

Preliminary Guideline for the Determination of Buffer Zones 2014
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SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Low-risk mining operations
Mining operations (including mine and mine waste but
excluding underground mining operations) posing a low water
quality risk to water resources including mining of the
following substances: Antimony (Small mines), Base metals
(Copper Cadmium, Cobalt, Iron ore, Molybdenum, Nickel, Tin,
Vanadium) – oxide ore, Chrome, Diamonds and precious
stones, Phosphate, Platinum, Magnesium, Manganese,
Mineral sands (Ilmenite, Titanium, Rutile, Zircon), Zinc and
Lead, Industrial Minerals (Andalusite, Barite, Bauxite, Cryolite,
Fluorspar)
Plant and plant waste from
mining operations – high risk
activities
Waste generated from plant and plant waste from processing
of minerals and metals extracted from the ground, which pose
a high water quality risk to water resources. These include:
Antimony (Large mines), Asbestos, base metals (Copper
Cadmium, Cobalt, Iron ore, Molybdenum, Nickel, Tin,
Vanadium), Chrome (Large mines), Coal, Gold, silver,
uranium, Zinc & Lead
Plant and plant waste from
mining operations – moderate
risk activities
Waste generated from plant and plant waste from processing
of minerals and metals extracted from the ground, which pose
a moderate water quality risk to water resources. These
include: Diamonds and precious stones(Large mines),
Phosphate (Large mines), Platinum, Magnesium (Large
mines), Manganese (Large mines), Mineral sands (Ilmenite,
Titanium, Rutile, Zircon) – (Large mines).
Plant and plant waste from
mining operations – low risk
activities
Waste generated from plant and plant waste from processing
of minerals and metals extracted from the ground, which pose
a low water quality risk to water resources. These include:
Diamonds and precious stones(small mines), Phosphate
(Small mines), Magnesium (Small mines), Manganese (Small
mines), Mineral sands (Ilmenite, Titanium, Rutile, Zircon) –
(Small mines), Industrial Minerals (Andalusite, Barite, Bauxite,
Cryolite, Fluorspar)

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98
SECTOR SECTOR DESCRIPTION LAND USE / ACTIVITY DESCRIPTION OF LAND USE / ACTIVITY
Moderate-risk quarrying
operations
Quarrying operations of minerals with a moderate water
quality risk to water resources. These include: Granite,
Cement limestone, Limestone, Slate
Low-risk quarrying operations
Quarrying operations of minerals with a low water quality risk
to water resources. These include: Attapulgite (Special clays),
Calcrete, Clays, Dolerite, Kyanite, Mica, Norite (Dimension
stone), Pyrophyllite, Quartzite (Dimension Stone and
abrasive), Sand and Gravel, Siltstone Fines, Soil, Bentonite
(Special clays), CaC03, Diatomaceous Earth, Feldspar,
Graphite, Lime (Produced from limestone), Mineral
Aggregates, Phosphate Rock, Quartz, Rare earths, Shale,
Silica, Talc, Calcite, Dolomite, Fullers Earth, Kaolin,
Montmorillonite, Pumice, Quartzite, Salt, Siltstone (Dimension
Stone), Vermiculite
Exploratory drilling Drilling for mineral/fuel exploration.

Preliminary Guideline for the Determination of Buffer Zones 2014
99
Annexure 7 – Specific limits set for evaluating different threat types
assessed (electronic copy only – refer to the CD provided)
Annexure 8 – Summary of Average Event Mean Concentrations (EMCs)
for sectors & sub-sectors (electronic copy only – refer to the CD
provided)
Annexure 9 – Event Mean Concentrations (EMCs) for sectors & sub-
sectors obtained from international literature (electronic copy only –
refer to the CD provided)
Annexure 10 – Initial desktop threat ratings based on expert workshops
(electronic copy only – refer to the CD provided)

Preliminary Guideline for the Determination of Buffer Zones 2014
100
Annexure 11 – Hydrological sensitivity analysis
A hydrological sensitivity analysis was undertaken by Hydro-Geomorphic Systems, based at the
University of KwaZulu-Natal31 in order to better understand how a suite of climatic and site-based
attributes affect peak discharge (when surface flows are most likely to take place).
Understanding such relationships is important from a buffer zone perspective since buffer zones are
typically designed to assimilate contaminants in surface overland flows. The effect of climatic
conditions on overland flow is therefore likely to affect the risk of contaminants being washed from
land uses upstream of the buffer zone while site-based characteristics may affect the ability of the
buffer zone to slow flows and promote pollutant assimilation.
1. Methodology applied
The ACRU agrohydrological model (version 3) (Schulze, 1995) model was used to simulate a
hypothetical catchment of 1 km2 (1 km x 1 km) which included a 30 m buffer zone along the edge of
a river\stream, with an area of 0.03 km2. Above this buffer is the land use “section” of this
catchment, the area of which is 0.97 km2. A schematic of this hypothetical catchment is illustrated in
Figure 1.
Various simulations represented changes in slope, soil textures, land cover, mean annual
precipitation (MAP32) and rainfall intensity. The input climate data was from the quinary catchment
database and for the 50 year period 1950 to 1999. Five scenarios were simulated to establish the
sensitivity of changing the catchment land use, rainfall intensity, slope, change in the buffer zone
vegetation, and change in the soil texture. For the rainfall intensity simulations, the Schmidt-Schulze
equation (Schmidt and Schulze, 1984) was used for peak discharge, as it considers the 30-minute
rainfall intensity (mm.h-1) for the 2-year return period. The other peak discharge simulations used
the SCS equation as it considers the impact of land use and soil on peak discharge. The land uses
considered included grassland, maize cultivation, commercial forestry, urban residential and
industrial. In the buffer zone, the vegetation cover included grassland in good condition, degraded
grassland and bare soil. Four rainfall intensity scenarios of 90 mm.h-1, 70 mm.h-1, 50 mm.h-1 and 30
mm.h-1 were considered in the simulation of peak discharge. Slope was varied from a 0-45o. Eight
soil textural classes were also considered.
31 Authors included: Mr Nicholas Davis (MSc Hydrology); Dr Hartley Bulcock (PhD hydrology); and Mrs Lauren Bulcock
(MSc Bioresource Systems).
32 Rainfall data for a suite of test-catchments reflecting the variability in MAR across the country was selected. MARs in
these catchments were 192 mm, 666 mm, 1117 mm and 1281 mm for very low to very high MAR classes and were
selected as MAR in each catchment reflected approximate mid-points for the MAR classes used in simulations.

Preliminary Guideline for the Determination of Buffer Zones 2014
101
Figure 1. Schematic of the hypothetical 1 km2 catchment used for hydrological simulations.
Given that the buffer zone model has been developed by applying a series of modifiers to a given
“reference” scenario, it was important to set reference parameters against which changes in site-
characteristics could be evaluated. For this exercise, the baseline simulation considered the land
use to be grassland, slope to be between 5-10 degrees, the buffer zone vegetation to be grass in
good condition, and the soil texture to be clay-loam. These variables were kept constant for all
simulation unless the scenarios required them to be changed (for example, the land use was
grassland for all scenarios unless the scenario was specifically considering a change of land use,
etc.). The parameters that were kept constant are highlighted in grey in the results tables. The
rainfall intensity zones were not kept constant for all simulations because they were only required in
the calculation of peak discharge using the Schmidt-Schulze equation. Thereafter, the model did not
require rainfall intensity for the other simulations. Table 1 below details the input parameters used
for to each simulation.
Not to Scale
Landuse
(Area = 0.97 km2)
Buffer zone
(Area = 0.03 km2)
Channel
1 km
1 km
30 m

Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 1. Input variables used
SIMULATION VARIABLE
CHANGED FULL VARIABLE NAME VALUE
XI30_Z1 MAP\XI30 Mean Annual Precipitation (mm) \
30min 2yr return period rainfall
intensity (mm\h)
666; 192; 1117; 1281
[90 mm.h-1]
XI30_Z2 MAP\XI30 Mean Annual Precipitation (mm) \
30min 2yr return period rainfall
intensity (mm\h)
666; 192; 1117; 1281
[70 mm.h-1]
XI30_Z3 MAP\XI30 Mean Annual Precipitation (mm) \
30min 2yr return period rainfall
intensity (mm\h)
666; 192; 1117; 1281
[50 mm.h-1]
XI30_Z4 MAP\XI30 Mean Annual Precipitation (mm) \
30min 2yr return period rainfall
intensity (mm\h)
666; 192; 1117; 1281
[30 mm.h-1]
LU_GRASS CROPNO Land cover type Southern tall grassveld
LU_FORESTRY CROPNO Land cover type Eucalyptus general
LU_INDUSTRIAL CROPNO Land cover type Industrial
LU_MAIZE CROPNO Land cover type Maize October
planting date
LU_RESIDENTIAL CROPNO Land cover type Residential (formal,
medium density)
LUS_GRASS (1) SLOPE Slope (%) 2.2
LUS_GRASS (5) SLOPE Slope (%) 5
LUS_GRASS(10) SLOPE Slope (%) 16.5
LUS_GRASS(15) SLOPE Slope (%) 27.5
LUS_GRASS(30) SLOPE Slope (%) 49.5
LUS_GRASS(45) SLOPE Slope (%) 82.5
BZ_GRASS_GOOD CROPNO Buffer zone land cover type Veld in good condition
– general
BZ_GRASS_DEG CROPNO Buffer zone land cover type Veld in poor condition
– general
BZ_GRASS_BARE_SOIL CROPNO Buffer zone land cover type Bare Rock\soil
BZ_GRASS_SLOPE(1) SLOPE Slope of only buffer zone (%) 2.2
BZ_GRASS_SLOPE(5) SLOPE Slope of only buffer zone (%) 5
BZ_GRASS_SLOPE(10) SLOPE Slope of only buffer zone (%) 16.5
BZ_GRASS_SLOPE(15) SLOPE Slope of only buffer zone (%) 27.5
BZ_GRASS_SLOPE(30) SLOPE Slope of only buffer zone (%) 49.5
BZ_GRASS_SLOPE(45) SLOPE Slope of only buffer zone (%) 82.5
BZ_SOIL_TEXT1 ITEXT Soil texture 1 (Clay)
BZ_SOIL_TEXT2 ITEXT Soil texture 2 (Loam)
BZ_SOIL_TEXT3 ITEXT Soil texture 3 (Sand)
BZ_SOIL_TEXT4 ITEXT Soil texture 4 (Loamy sand)
BZ_SOIL_TEXT5 ITEXT Soil texture 5 (Sandy loam)
BZ_SOIL_TEXT7 ITEXT Soil texture 7 (Sandy Clay loam)
BZ_SOIL_TEXT8 ITEXT Soil texture 8 (Clay loam)
BZ_SOIL_TEXT10 ITEXT Soil texture 10 (Sandy clay)

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2. Results of the hydrological sensitivity assessment
The results presented in the tables below are for the outputs of total streamflow from the
subcatchment and includes the upstream contributions (CELRUN) and peak discharge (QPEAK)
although peak discharge is the variable of interest to this study. The simulations were for four
climatic zones with different MAP ranging from 0-400 mm to >1200 mm. The QPEAK values were
summed for the 50 year period in order to be able to make a relative comparison of the impact of
each scenario. It was decided for this study that the QPEAK value would be used as this accounts
for rainfall intensity, which was a required outcome of this study and provides a useful surrogate
measure for surface overland flow (flows carrying diffuse pollutants through the buffer zone).
2.1. Land use impacts
The comparison shows that land use has a clear impact on runoff characteristics with land uses
dominated by high levels of hardened surfaces / bare ground leading to increased peak discharge
(Table 3.1.2). When compared to reference conditions, this shows that maize lands and industrial
land uses in particular can result in peak discharges that are more than double that simulated under
natural (grassland) conditions (Table 3.1.3). The importance of climate is also clearly demonstrated
here, with a dramatic reduction in simulated peak discharge occurring in drier climatic conditions
and is discussed further in section 3.6. Table 3.1.4 shows that peak discharge responds consistently
to land use changes across all climatic ranges.
These changes in peak discharge, together with potential presence of pollutants contribute to the
risk of land use activities in delivering pollutants into adjacent water resources. These variations
have already been subjectively accounted for in the land use risk assessment process but reinforce
the importance of land use adjacent to water resources in contributing to stormwater runoff into
buffer zones and the associated risk of pollutants being transported into adjacent water resources.

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Table 3.1.1. Impacts of changes in land use on runoff from the test
catchment Table 3.1.2. Impacts of changes in land use on peak quick flows from the
test catchment
land use MAP (mm) land use MAP (mm)
0-400 401-800 801-1200 >1200 0-400 401-800 801-1200 >1200
celrun (mm)
Grassland 0.86 69.26 355.7 489.34
Qpeak (m3.s-1)
Grassland 5.93 388.77 1694.20 2187.84
Maize 1.1 81.92 479.28 639.14 Maize 15.01 831.47 3633.90 4670.81
Forestry 0.56 58.1 265.14 319.36 Forestry 3.94 383.83 1693.58 2124.39
Residential 0.7 67.56 317.98 418.02 Residential 7.34 625.95 2614.43 3337.37
Industrial 0.78 71.44 351.8 483.3 Industrial 13.41 1003.01 4254.32 5468.79
Table 3.1.3. Variation in peak discharge relation to
"Reference" conditions
Table 3.1.4 Consistency of peak discharge responses to
rainfall intensity zones across different MAP zones
land use MAP (mm) land use MAP (mm)
0-400 401-800 801-1200 >1200 0-400 401-800 801-1200 >1200 Average
Qpeak (m3.s-1)
Grassland 0.00 0.23 1.00 1.29
Qpeak (m3.s-1)
Grassland 1.00 1.00 1.00 1.00 1.00
Maize 0.01 0.49 2.14 2.76 Maize 2.53 2.14 2.14 2.13 2.24
Forestry 0.00 0.23 1.00 1.25 Forestry 0.66 0.99 1.00 0.97 0.91
Residential 0.00 0.37 1.54 1.97 Residential 1.24 1.61 1.54 1.53 1.48
Industrial 0.01 0.59 2.51 3.23 Industrial 2.26 2.58 2.51 2.50 2.46
2.2. Rainfall intensity
The simulation outcomes show that the rainfall intensity zone has a moderate effect on peak discharge across all ranges of MAP considered. In high
rainfall intensity zones, a 24% increase in peak discharge can be expected over "Reference" whereas a reduction of 25% and 51% can be expected in
rainfall zones 3 and 4, respectively (Table 3.2.3). This relationship is consistent across different MAP zones (Table 3.2.4) and a suite of adjustment
factors have therefore been included relative to the "Reference" to account for variations in Rainfall intensity zone in the buffer zone model (Table
3.2.5).

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105
Table 3.2.1 Impacts of changes in rainfall intensity on runoff
from the test catchment
Table 3.2.2 Effect of rainfall intensity on peak discharge from
the test catchment
Rainfall zone
MAP (mm)
Rainfall zone
MAP (mm)
0-
400 401-800 801-1200 >1200 0-
400
401-800 801-1200 >1200
celrun (mm)
Zone 4 0.86 69.26 355.7 489.34
Qpeak
(m3 s
1)
Zone 4 5.00 84.00 204.00 225.00
Zone 3 0.86 69.26 355.7 489.34 Zone 3 4.00 67.00 164.00 182.00
Zone 2 0.86 69.26 355.7 489.34 Zone 2 3.00 50.00 123.00 137.00
Zone 1 0.86 69.26 355.7 489.34 Zone 1 2.00 32.00 80.00 89.00
Table 3.2.3 Variation in peak discharge relation to
"Reference" conditions
Table 3.2.4. Consistency of peak discharge responses to rainfall
intensity zones across different MAP zones
Rainfall zone
MAP (mm)
Rainfall zone
MAP (mm)
0-
400 401-800 801-1200 >1200 0-
400 401-800 801-1200 >1200 Average
Qpeak (m3.s-
1)
Zone 4 0.03 0.51 1.24 1.37
Qpeak (m3.s-
1)
Zone 4 1.25 1.25 1.24 1.24 1.25
Zone 3 0.02 0.41 1.00 1.11 Zone 3 1.00 1.00 1.00 1.00 1.00
Zone 2 0.02 0.30 0.75 0.84 Zone 2 0.75 0.75 0.75 0.75 0.75
Zone 1 0.01 0.20 0.49 0.54 Zone 1 0.50 0.48 0.49 0.49 0.49
Table 3.2.5. Simulated adjustment factors for buffer zones to account for
Rainfall intensity
Rainfall
intensity
zone
Category Zone 4 Zone 3 Zone 2 Zone 1
Modifier 1.25 1.00 0.75 0.49

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2.3. Slope of the buffer zone
As expected, simulation outcomes show that the slope angle across the buffer zone has a clear impact on peak discharges across all ranges of MAP
considered (Table 3.3.2). In situations where slopes are steep, an increase of 66% above reference was simulated while this declined to only 56% of
reference where buffer zones were very gently sloping (Table 3.3.3). This relationship is consistent across different MAP zones (Table 3.3.4) and a
suite of adjustment factors have therefore been included relative to the "Reference" to account for variations in Rainfall intensity zone in the buffer
zone model (Table 3.2.5).
Table 3.3.1. Impacts of changes in the slope of the buffer
zone on runoff from the test catchment
Table 3.3.2. Effect of slope (degrees) on peak discharge
from the test catchment
degrees MAP (mm) degrees MAP (mm)
0-400 401-800 801-1200 >1200 0-400 401-800 801-1200 >1200
celrun (mm)
0-1 0.86 69.26 355.7 489.34
Qpeak (m3.s-1)
0-1 3 51 125 139
0-5 0.86 69.26 355.7 489.34 0-5 4 65 160 177
5-10 0.86 69.26 355.7 489.34 5-10 5 93 227 251
10-15 0.86 69.26 355.7 489.34 10-15 7 109 265 292
15-30 0.86 69.26 355.7 489.34 15-30 8 130 315 348
30-45 0.86 69.26 355.7 489.34 30-45 9 151 367 405

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Table 3.3.3. Variation in peak discharge relation to
"Reference" conditions Table 3.3.4. Consistency of peak discharge responses to slope
variation across different MAP zones
degrees MAP (mm) degrees MAP (mm)
0-400 401-800 801-1200 >1200 0-400 401-800 801-1200 >1200
Average
Qpeak (m3.s-1)
0-1 0.01 0.22 0.55 0.61
Qpeak (m3.s-1)
0-1 0.60 0.55 0.55 0.55 0.56
0-5 0.02 0.29 0.70 0.78 0-5 0.80 0.70 0.70 0.71 0.73
5-10 0.02 0.41 1.00 1.11 5-10 1.00 1.00 1.00 1.00 1.00
10-15 0.03 0.48 1.17 1.29 10-15 1.40 1.17 1.17 1.16 1.23
15-30 0.04 0.57 1.39 1.53 15-30 1.60 1.40 1.39 1.39 1.44
30-45 0.04 0.67 1.62 1.78 30-45 1.80 1.62 1.62 1.61 1.66
Table 3.3.5. Simulated adjustment factors for buffer zones to account for variations in
buffer zone slope.
Slope of buffer
zone
Category 0-1 0-5 5-10 10-
15 15-30 30-45
Modifier 0.56 0.73 1.00 1.23 1.44 1.66
2.4. Vegetation characteristics of the buffer zone
As expected, simulated results show that buffer zone vegetation has a clear impact on peak discharge with higher simulated peak discharge volumes
occurring in situations where the buffer zone is degraded (lower basal cover) that natural grassland reference conditions (Table 3.4.2). Indeed, where
vegetation is lacking (bare soil), peak discharge is likely to be more than double that observed under reference conditions (good condition grassland)
(Table 3.4.3). This emphasizes the importance of buffer zone management in slowing surface overland flow, promoting infiltration and allowing
pollutants to be deposited in the buffer zone. A range of preliminary adjustment factors have therefore been calculated relative to the "Reference" to
account for variations in buffer zone vegetation characteristics in the buffer zone model.

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108
Table 3.4.1 Impacts of changes in the buffer zone vegetation
characteristics on runoff from the test catchment
Table 3.4.2 Effect of changes in buffer zone vegetation
characteristics on peak discharge from the test catchment
Buffer
vegetation
MAP (mm)
Buffer vegetation
MAP (mm)
0-
400
401-800 801-1200 >1200 0-
400
401-800 801-1200 >1200
celrun
good grass 0.86 69.26 355.7 489.34
Qpeak
good grass 0.2 12.4 53 69
degraded grass 0.92 69.76 358.08 492.84 degraded grass 1.3 28.5 114 149
bare soil 0.9 70.32 359.62 494.54 bare soil 1.4 33 129 168
Table 3.4.3 Variation in peak discharge relation to
"Reference" conditions Table 3.4.4 Consistency of peak discharge responses to variation in
buffer vegetation characteristics across different MAP zones
Buffer
vegetation
MAP (mm) Buffer
vegetation
MAP (mm)
0-
400
401-800 801-1200 >1200 0-
400
401-800 801-1200 >1200 Average*
Qpeak
good grass 0.00 0.23 1.00 1.30
Qpeak
good grass 1.00 1.00 1.00 1.00
1.00
degraded grass 0.02 0.54 2.15 2.81 degraded grass 6.50 2.30 2.15 2.16 2.20
bare soil 0.03 0.62 2.43 3.17 bare soil 7.00 2.66 2.43 2.43 2.51
* In this case, the average excludes very low MAR values which show
inconsistencies in typical relationships
Table 3.4.5. Simulated adjustment factors for buffer zones to account for variations in buffer vegetation characteristics.
Condition of
buffer zone
vegetation
Category good
grass
degraded
grass
bare
soil
Modifier 1.00 2.20 2.51

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2.5. Soil texture in the buffer zone
This simulation shows a reduction in peak discharge where soil characteristics of the buffer zone are more coarsely textured (Table 3.4.2). When
compared with reference (clay-loam soils), there is approximately a 25% reduction in peak discharge for sandy soils while clay soils result in a
considerable increase in discharge (Table 3.4.3). This is in line with expectations as such soils have a higher infiltration capacity than fine textured
soils. A range of preliminary adjustment factors have therefore been calculated relative to the "Reference" to account for variations in variations in soil
texture in the buffer zone.
Table 3.5.1. Impacts of changes in the soil textural
characteristics in the buffer zone on runoff from the test
catchment
Table 3.5.2 Effect of changes in soil texture in the buffer
zone on peak discharge from the test catchment
Soil texture
MAP (mm)
Soil texture
MAP (mm)
0-
400 401-800 801-1200 >1200 0-
400 401-800 801-1200 >1200
celrun (mm)
Sand 0.78 69.74 358.16 491.42
Qpeak (m3.s-1)
Sand 0.13 8.9 39 51
Loamy sand 0.8 69.42 356.76 490.08 Loamy sand 0.13 9 39 50
Clay loam 0.86 69.26 355.7 489.34 Clay loam 0.19 12.1 53 68
Sandy loam 0.84 69.34 356.26 489.62 Sandy loam 0.23 15.5 67 86
Loam 0.84 69.28 355.98 489.44 Sandy loam 0.23 15.5 67 86
Sandy clay
loam 0.84 69.28 355.98 489.44 Loam 0.24 15.5 67 86
Sandy clay 0.78 69.6 357.76 490.92
Sandy clay
loam 0.28 18.5 80 102
Clay 3.64 108.84 396.18 529 Clay 0.83 24.7 85 112

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Table 3.5.3 Variation in peak discharge relation to
"Reference" conditions
Table 3.5.4 Consistency of peak discharge responses to variation in
soil textural characteristics of the buffer zone across different MAP
zones
Soil texture
MAP (mm)
Soil texture
MAP (mm)
0-
400 401-800 801-1200 >1200 0-
400 401-800 801-1200 >1200 Average*
Qpeak (m3.s-1)
Sand 0.00 0.17 0.74 0.96
celrun (mm)
Sand 0.68 0.74 0.74 0.75 0.74
Loamy sand 0.00 0.17 0.74 0.94 Loamy sand 0.68 0.74 0.74 0.74 0.74
Clay loam 0.00 0.23 1.00 1.28 Clay loam 1.00 1.00 1.00 1.00 1.00
Sandy loam 0.00 0.29 1.26 1.62 Sandy loam 1.21 1.28 1.26 1.26 1.27
Sandy loam 0.00 0.29 1.26 1.62 Sandy loam 1.21 1.28 1.26 1.26 1.27
Loam 0.00 0.29 1.26 1.62 Loam 1.26 1.28 1.26 1.26 1.27
Sandy clay
loam 0.01 0.35 1.51 1.92
Sandy clay
loam 1.47 1.53 1.51 1.50 1.51
Clay 0.02 0.47 1.60 2.11 Clay 4.37 2.04 1.60 1.65 1.76
* In this case, the average excludes very low MAR values which show
inconsistencies in typical relationships
Table 3.5.5. Simulated adjustment factors for buffer zones to account for variations in buffer zone
soil characteristics.
Soil texture of
buffer zone
Category Sand Loamy
sand
Clay
loam
Sandy
loam
Sandy
loam Loam
Sandy
clay
loam
Clay
Modifier 0.74 0.74 1.00 1.27 1.27 1.27 1.51 1.76

Preliminary Guideline for the Determination of Buffer Zones 2014
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2.6. Mean Annual Precipitation (MAP)
This simulation shows that MAP has a significant and consistent effect on peak discharge with dramatic reductions in discharge expected in drier parts
of the country (Tables 3.6.1 to 3.6.6). Indeed, in very low rainfall areas, even peak discharge is likely to be very low due to typically small rainfall
events. This suggests that the risk of contaminated surface flows emanating from land use activities adjacent water resources is likely to be negligible
in very dry areas and significantly lower in moderate rainfall areas (MAP = 401-800 mm) than in high rainfall areas (MAP = 801-1200 mm). A range of
preliminary adjustment factors have therefore been calculated relative to the "Reference" to account for variations in MAP in the buffer zone model.
Table 3.6.1 Consistency of the effect of MAP on peak
discharge across changes in land use types
Table 3.6.2 Consistency of the effect of MAP on peak
discharge across different rainfall intensity zones
Land use
MAP (mm)
Rainfall zone
MAP (mm)
0-400 401-
800
801-
1200 >1200 0-400 401-
800
801-
1200 >1200
Qpeak (m3.s-1)
Grassland 0.00 0.23 1.00 1.29
Qpeak
(m3 s
1)
Zone 4 0.02 0.41 1.00 1.10
Maize 0.00 0.23 1.00 1.29 Zone 3 0.02 0.41 1.00 1.11
Forestry 0.00 0.23 1.00 1.25 Zone 2 0.02 0.41 1.00 1.11
Residential 0.00 0.24 1.00 1.28 Zone 1 0.03 0.40 1.00 1.11
Industrial 0.00 0.24 1.00 1.29 Average 0.02 0.41 1.00 1.11
Average 0.00 0.23 1.00 1.28

Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 3.6.3 Consistency of the effect of MAP on peak
discharge in relation to changes in buffer zone slope classes
Table 3.6.4 Consistency of the effect of MAP on peak
discharge in relation to changes in buffer zone vegetation
characteristics
degrees
MAP (mm) Buffer
vegetation
MAP (mm)
0-400 401-800 801-1200 >1200 0-
400
401-800 801-1200 >1200
Qpeak (m3.s-1)
0-1 0.02 0.41 1.00 1.11
Qpeak
(
m3.s-1
)
good grass 0.00 0.23 1.00 1.30
0-5 0.03 0.41 1.00 1.11 degraded grass 0.01 0.25 1.00 1.31
5-10 0.02 0.41 1.00 1.11 bare soil 0.01 0.26 1.00 1.30
10-15 0.03 0.41 1.00 1.10 Average 0.01 0.25 1.00 1.30
15-30 0.03 0.41 1.00 1.10
30-45 0.02 0.41 1.00 1.10
Average 0.02 0.41 1.00 1.11

Preliminary Guideline for the Determination of Buffer Zones 2014
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Table 3.6.5 Consistency of the effect of MAP on peak
discharge in relation to changes in buffer zone textural
characteristics
Table 3.6.6 Consistency of the effect of MAP on peak
discharge across different criteria considered during the
simulation
Soil texture MAP (mm) Criteria MAP (mm)
0-400 401-800 801-1200 >1200 0-400 401-800 801-1200 >1200
Qpeak (m3.s-1)
Sand 0.00 0.23 1.00 1.31
Qpeak (m3.s-1)
Land use 0.00 0.23 1.00 1.28
Loamy sand 0.00 0.23 1.00 1.28 Rainfall Zone 0.02 0.41 1.00 1.11
Clay loam 0.00 0.23 1.00 1.28 Slope 0.02 0.41 1.00 1.11
Sandy loam 0.00 0.23 1.00 1.28 Buffer
vegetation 0.01 0.25 1.00 1.30
Loam 0.00 0.23 1.00 1.28 Soil texture 0.00 0.24 1.00 1.29
Sandy clay
loam 0.00 0.23 1.00 1.28 Overall
Average 0.01 0.31 1.00 1.22
Sandy clay 0.00 0.23 1.00 1.28
Clay 0.01 0.29 1.00 1.32
Average 0.00 0.24 1.00 1.29
Table 3.6.7. Simulated adjustment factors for buffer zones to account for variations in MAP.
Mean Annual
Precipitation
Category 0-400 401-
800
801-
1200 >1200
Modifier 0.01 0.31 1.00 1.22
3. References
Schmidt, E.T., Schulze, R.E. (1984). Improved estimation of peak flow rates using modified SCS lag equations. Water Research Commission, Pretoria,
RSA.
Schulze, R.E. (1995). Hydrology and agrohydrology. A text to accompany the ACRU 3.00 agrohydrological modelling system. Department of
Agricultural Engineering, University of Natal, Pietermaritzburg, RSA.

Preliminary Guideline for the Determination of Buffer Zones 2014
114
Annexure 12 – Guidelines for assessing the sensitivity of wetlands to
lateral land-use inputs
The focus of this assessment is on the sensitivity of wetlands to lateral impacts rather than broader
catchment impacts. The sensitivity of the wetland itself, rather than the sensitivity of important biota
is assessed here. Where important biodiversity elements are present, additional protection
measures need to be identified in line with the sensitivity of focus species to threats identified.
Indicators have been defined in order to assess the sensitivity of wetlands to common threats posed
by lateral land-use impacts. The indicators were scored relative to a typical “reference” wetland of
intermediate sensitivity and are used to calculate a sensitivity score and associated class for each
threat type under consideration.
1. Sensitivity to changes in water quantity (volumes of flow) from lateral inputs
Table 1. Wetland characteristics affecting the sensitivity of the water resource to changes in the
volumes of inputs from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Size of the wetland relative
to (as a percentage of) its
catchment
Large
(>20%) 10-20 Intermediate
(6-10%) 2-5% Small (<2%)
The extent to which the
wetland (HGM) setting is
generally characterized by
sub-surface water input
High
(Hillslope
seepage)
Moderatel
y high
Intermediate
(The
remaining
HGM types)
Moderately
low
Low
(Floodplain)
1.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to changes in water inputs. Large
wetlands have a greater inherent buffer capacity and are therefore less likely to be affected by
changes in lateral water inputs than small wetlands where moderate changes in water inputs could
have a substantial impact by affecting hydrologic functions and reducing water available to support
wetland biota.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
1.2 Size of the wetland relative to its catchment
Rationale: Reinlet and Taylor (2001) observed that wetlands that were small in relation to their
contributing watersheds had greater water level fluctuations and were dominated by surface inflow.
Wetlands that were larger in comparison to their contributing watersheds had smaller water level
fluctuations and more groundwater interface. By implication then, the larger the wetland relative to
its catchment, the greater the extent to which a wetland is fed hydrologically by lateral inputs from its
immediate catchment as opposed to from an upstream area, and the more sensitive it will be to

Preliminary Guideline for the Determination of Buffer Zones 2014
115
changes in water quantity from lateral inputs. At the one extreme, a wetland fed almost entirely by
lateral inputs would be the most sensitive, whereas a wetland fed almost entirely from an upstream
area would be the least sensitive.
Method: This assessment requires that the catchment of the HGM unit adjacent to the proposed
development be roughly estimated. Once estimated, the relative extent of the wetland is compared
to that of catchment. Here, it is important to note that although the wetland itself may be large, the
HGM unit potentially impacted may be small, and largely reliant on lateral inputs. A sensitivity score
is then assigned with reference to the diagram above and wetland: area ratios indicated in Table 1.
Note: In the case of groundwater-fed systems, sensitivity should be based on the anticipated
importance of lateral flows to the groundwater system relative to the broader recharge area.
1.3 The extent to which the HGM setting is characterized by sub-surface water input
Rationale: Generally, hillslope seepages are fed primarily from lateral inputs from their immediate
catchment, whilst floodplains are fed primarily from an upstream area (although some floodplains,
particularly those in higher rainfall areas, may be fed by extensive lateral inputs). Other HGM types
tend to be intermediate.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 1. At a
rapid level it is assumed that hillslope seepages are characterized by high levels of lateral input and
floodplains by low levels, and further that the other HGM types are characterized by intermediate
levels. Where site assessments are undertaken, this assumption should be verified and sensitivity
scores adjusted where required based on field observations.
2. Sensitivity to changes in patterns of flow (frequency, amplitude, direction of flow) from
lateral inputs.
Table 2. Wetland characteristics affecting the sensitivity of the water resource to changes in the
patterns of flow from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large
(>300 ha)
Size of the wetland relative
to (as a percentage of) its
catchment
Large
(>20%) 10-20% Intermediate
(6-10%) 2-5% Small
(<2%)
Average slope of the
wetland’s catchment <3% 3-5% 6-8% 9-11% >11%
Very high sensitivity
(Score = 1.5)
Intermediate sensitivity
(Score=1.0)
Very low sensitivity
(
Score=0.5
)

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116
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Inherent runoff potential of
catchment soils Low Moderately
low Moderate Moderately
high High
The extent to which the
wetland (HGM) setting is
generally characterized by
sub-surface water input
High
(Hillslope
seepage)
Moderately
high
Intermediate
(The
remaining
HGM types)
Moderately
low
Low
(Floodplain)
2.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to changes in water inputs. Large
wetlands have a greater inherent buffer capacity and are therefore less likely to be affected by
increased flood peaks than small wetlands where moderate changes in water inputs could have a
substantial impact by affecting water levels and potentially accelerating erosive processes.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
2.2 Size of the wetland relative to its catchment
Rationale: The larger the wetland relative to its catchment, the greater the extent to which a wetland
is fed hydrologically by lateral inputs from its immediate catchment as opposed to from an upstream
area, and the more sensitive it will be to changes in changes in timing from lateral inputs. At the
one extreme, a wetland fed almost entirely by lateral inputs would be the most sensitive, whereas a
wetland fed almost entirely from an upstream area would be the least sensitive.
Method: Use method 1.2 to determine the size of the wetland relative to the catchment. A sensitivity
score is then assigned with reference to the diagram above and wetland: area ratios indicated in
Table 2. Note: In the case of groundwater-fed systems, sensitivity should be based on the
anticipated importance of lateral flows to the groundwater system relative to the broader recharge
area.
2.3 Average slope of the wetland’s catchment
Rationale: The steeper the slope and the greater the inherent runoff potential of the soils, the lower
will be the infiltration and, in turn, the higher flood peaks are likely to be. Wetland systems located
at the base of steep catchments with poor infiltration rates are therefore likely to be characterized by
naturally flashy flow. Wetlands located below catchments with gentle slopes and high permeabilities
are however likely to be characterized more by higher base flows and less flashy flows. These
systems are therefore likely to be more sensitive to changes in flow patterns than those that are
subject to naturally high variations in flows.
Very high sensitivity
(Score = 1.5)
Intermediate sensitivity
(Score=1.0)
Very low sensitivity
(
Score=0.5
)

Preliminary Guideline for the Determination of Buffer Zones 2014
117
Method: Average slope can be roughly calculated simply from available topographic maps or from
GIS datasets or Google Earth information. This is done by first taking elevation readings from (i) the
upper-most point of the catchment and (ii) the site being assessed and calculating the altitudinal
change. The distance between these points is then measured and average slope estimated by
dividing the altitudinal change by the distance from the upper reaches of the catchment.
2.4 The inherent runoff potential of catchment soils
Rationale: The ability of a catchment to partition runoff into surface and sub-surface flow
components depends largely on prevailing catchment conditions, which may be the result of both
natural and anthropogenic processes. Soils are a key natural regulator of catchment hydrological
response due the capacity that soils have for absorbing, retaining and releasing/redistributing water
(Schulze, 1989). Catchments dominated with deep, well-drained soils generally have high rates of
permeability and thus a greater proportion of rainfall can infiltrate into the soil profile. Consequently
catchments with highly permeable soils therefore have a much lower runoff potential compared to
soils with a low permeability (e.g. clay soils). As such, wetlands fed by catchments characterized by
higher permeabilities are characterized by less flashy flows than those fed by catchments
characterized by low permeabilities. Wetlands fed by catchment inputs which are naturally flashy
are therefore regarded as less sensitive to changes in the pattern of lateral water inputs (e.g.
increased runoff during heavy rains) than those characterised by less variable flow regimes.
Method: The Soil Conservation Services method for Southern Africa (SCS-SA) uses information of
hydrologic soil properties to estimate surface runoff from a catchment (Schulze et al., 1992). With
reference to the SCS-SA (Figure 1 and Table 3), determine the appropriate hydrological soil group
that defines the entire catchment based on available soils information.
Figure 1. Distribution of SCS soil groups A to D over South Africa at a spatial resolution of Land
Type polygons (Schulze 2010)

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118
Table 3. Runoff potential classes (after Schulze, at al. 1992)
LOW RUNOFF
POTENTIAL MODERATELY LOW
RUNOFF POTENTIAL MODERATELY HIGH
RUNOFF POTENTIAL HIGH RUNOFF
POTENTIAL
Soil Group A:
Infiltration is high and
permeability is rapid.
Overall drainage is
excessive to well-
drained.
Soil Group B:
Moderate infiltration
rates, effective depth
and drainage.
Permeability slightly
restricted.
Soil Group C:
Infiltration rate is slow
or deteriorates rapidly.
Permeability is
restricted.
Soil Group D: Very
slow infiltration and
severely restricted
permeability. Includes
soils with high shrink-
swell potential.
2.5 The extent to which the HGM setting is characterized by sub-surface water input
Rationale: Generally, hillslope seepages are fed primarily from lateral inputs from their immediate
catchment, and are typically located in steep settings. These wetlands are therefore likely to be
most sensitive to changes in runoff characteristics. Floodplains on the other hand, are characterized
by highly variable flows and fed primarily from an upstream area (although some floodplains,
particularly those in higher rainfall areas, may be fed by extensive lateral inputs) and are likely to be
considerable less sensitive. Other HGM types tend to be intermediate.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 2. At a
rapid level it is assumed that hillslope seepages are characterized by high levels of lateral input and
floodplains by low levels, and further that the other HGM types are characterized by intermediate
levels. Where site assessments are undertaken, this assumption should be verified and sensitivity
scores adjusted where required based on field observations.
3. Sensitivity to changes in sediment inputs and turbidity from lateral inputs
Table 4. Wetland characteristics affecting the sensitivity of the water resource to changes in
sediment inputs and turbidity from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Perimeter to area ratio High (>1500 m
per ha)
Moderately
high
Moderate
(e.g. 1000 m
per ha)
Moderately
low
Low (<500 m
per ha)
Vulnerability of the
HGM type to sediment
accumulation
Depression –
endorheic, Flat
Depression
– exhoreic
Hillslope
seep, Valley
head seep,
Unchannelled
valley bottom
Channelled
valley-
bottom
Floodplain
wetland
Vulnerability of the site
to erosion given the
site’s slope and size
High
(Vulnerability
score>8)
Moderately
High
(Vulnerabilit
y score: 6-7)
Moderate
(Vulnerability
score :4-5)
Moderately
Low (
Vulnerability
score: 2-3)
Low
(Vulnerability
score <2)
Extent of open water,
particularly water that is
naturally clear
High (>9% of
the area)
Moderately
High (7-9%)
Moderate
(4-6%)
Low (0.5-
3%)
Very low
(<0.5%)

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119
Peat versus mineral
soils Peat - Mixed - Mineral
Sensitivity of the
vegetation to burial
under sediment
(adjacent planned
development)
High (e.g.
short growing
& slow
colonizing)
Moderately
high Intermediate Moderately
low
Low (e.g. tall
growing & fast
colonizing)
3.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to sediment inputs. Large
wetlands have a greater inherent buffer capacity and are therefore less likely to be affected by
changes in lateral sediment inputs than small wetlands where moderate changes in sediment inputs
could have a substantial impact by reducing storage capacity and affecting hydrologic functions.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
3.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral inputs of sediment. Long, thin wetlands are
therefore regarded as more susceptible than round or oval systems that would be less affected by
edge impacts.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter: area ratio. Use this to place the wetland into one of three classes
indicated.
3.3 Vulnerability of the HGM type to sediment accumulation
Rationale: Wetland systems that are well connected to the drainage network, characterized to
naturally high sediment inputs and subject to regular flushing are likely to be significantly less
susceptible to long-term impacts of sedimentation than wetlands that have not formed under these
processes. Floodplains are therefore likely to be least sensitive to increased sediment inputs, with
sediment deposition characteristic of these systems, together with high flows that may cause
considerable scouring of sediments. Pans, particularly those with a closed drainage system
however, are likely to be highly susceptible to increases in sediment inputs, as are flats, where any
accumulation of sediment is likely to remain. Other HGM types are likely to be of intermediate
sensitivity as detailed in Table 4.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 4.
3.4 Vulnerability of the site to erosion given the site’s slope and size
Rationale: Deposition of sediment within a wetland results in a steepening of the wetland’s gradient
on the downstream side of the deposition, which potentially increases the threat of erosion taking
place in this part of the wetland (Ellery et al., 2008). If the wetland is inherently vulnerable to
erosion then this threat is much more likely to be realized than if the vulnerability of the wetland is
low. Assessment of vulnerability is achieved by establishing the controls on the distribution and
occurrence of each HGM, and then assessing vulnerability through an analysis of longitudinal slope
in relation to wetland size.

Preliminary Guideline for the Determination of Buffer Zones 2014
120
Method: Measurement of the approximate longitudinal slope can be carried out using a
topographical map or available contour data. To calculate longitudinal slope, simply estimate the
change in elevation from the top to the bottom of the wetland and divide this value by the length of
the wetland and covert into a percentage. Measurement of the approximate area of the wetland is
based upon a map of the wetland (see 3.1). The vulnerability score is then derived with reference to
Figure 2 below), which assumes that wetland area is a proxy for discharge.
Figure 2. Vulnerability of HGM units to geomorphological impacts based on wetland size (a simple
surrogate for mean annual runoff) and wetland longitudinal slope (Macfarlane et al., 2007).
3.5 Extent of open water, particularly where water is naturally clear
Rationale: Increased water turbidity from suspended sediment reduces light penetration and thus
the light available for aquatic plant growth. Open water areas generally support a greater diversity
of submerged aquatic plants and/or aquatic fauna than occurs in dense stands of emergent
vegetation, particularly those with very shallow water. In addition, increased turbidity can reduce the
visual clarity for sighted organisms (e.g. fish) that typically make use of open water areas.
Method: This assessment is informed by a rapid site assessment to estimate the average extent of
open water. Where possible, this assessment should be supplemented with orthophoto maps or
aerial photographs that can be used to better understand the relative extent of open water habitat.
3.6 Peat versus mineral soils
Rationale: In wetlands, peat soils typically form under conditions of limited clastic sediment input,
whereas mineral soils typically (although not always) form under conditions of clastic sediment input
(Ellerey et al., 2008). Sheldon et al. (2003) further report that seeds, seedlings, and plants that
have evolved in wetland types in which sedimentation is rare are highly sensitive to buirial.
Therefore, anthropogenically-driven lateral inputs of clastic sediment would generally alter the
1 10 100 1000 10000
100000
0.01
0.1
1.0
10
0
2
5
8
10
PROTECTED
VULNERABLE
Wetland area (ha)
Longitudinal slope (%)

Preliminary Guideline for the Determination of Buffer Zones 2014
121
sediment regime more profoundly in a wetland area with peat soil than in a wetland area with
mineral soil.
Method: Peat is defined as organic soil material with a particularly high organic matter content
which, depending on the definition of peat, usually has at least 20% organic carbon by weight. The
presence of peat can be determined in the field based on observation of soil morphology and the
“feel” of the peat in the hand.
3.7 Sensitivity of the vegetation to burial under sediment
Rationale: Sedimentation may lead to burying of established seed banks and natural vegetation.
This may lead to a reduction in germination and survival rates of natural species, favouring plant
species tolerant to sediment inputs. The sensitivity of vegetation to increased sediment inputs is
therefore a useful indicator of sensitivity. In this regard, many mature plants, and especially woody
species, apparently are not harmed by a small amount of sediment (Wang et al., 1994). Growth of
species such as the reed Phragmites australis, also reportedly typically keeps pace with moderate
levels of sedimentation (Pyke and Havens, 1999). Typically short-growing, slow-growing and/or
species with limited capacity to colonize new areas are however likely to be most sensitive to burial
under sediment.
Method: This assessment is based on observation, during a rapid field visit, of the growth form of
the dominant plant species present in the HGM unit adjacent to planned developments. 4.
Sensitivity to increased inputs of nutrients (phosphates, nitrite, nitrate) from lateral inputs
Table 5. Wetland characteristics affecting the sensitivity of the water resource to increase nutrient
inputs from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5 ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Perimeter to area ratio High (>1500 m
per ha)
Moderately
high
Intermediate
(e.g. 1000 m per
ha)
Moderately
low
Low (<500 m
per ha)
Inherent level of
nutrients in the
landscape: Is the
wetland and its
catchment underlain by
sandstone?
- Yes Partially No -
Vulnerability of the HGM
type to nutrient
enrichment
Depression –
endorheic, Flat
Depression
– exhoreic
Hillslope seep,
Valley head
seep,
Unchannelled
valley bottom
Channelled
valley-
bottom
Floodplain
wetland
Extent of open water,
particularly water that is
naturally clear
High (>9% of
the area) Moderately
High (7-9%) Moderate (4-6%) Low (0.5-
3%) Very low
(<0.5%)
Sensitivity of the
vegetation to increased
availability of nutrients
High (e.g. short
and/or sparse
vegetation
Moderately
high
Intermediate
(e.g. short
vegetation with
Moderately
low
Low (e.g. tall
and dense
vegetation with

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122
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
cover with high
natural
diversity)
moderate natural
plant diversity) low natural
diversity)
4.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to nutrient inputs. Large wetlands
have a greater inherent buffer capacity and are therefore less likely to be affected by changes in
lateral nutrient inputs than small wetlands where moderate changes in nutrient inputs could have a
substantial impact on natural nutrient dynamics.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
4.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral nutrient inputs. Long, thin wetlands are
therefore regarded as more susceptible than round or oval systems that would be less affected by
edge impacts.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter:area ratio. Use this to place the wetland into one of three classes
indicated.
4.3 Inherent level of nutrients in the landscape
Rationale: Increased nutrient availability in naturally nutrient-poor systems allows grasses and
common opportunistic plants to outcompete rare plants that are adapted to nutrient-poor conditions
(Sheldon et al., 2003). Wetlands occurring in landscapes which are inherently low in nutrients
(notably, those dominated by sandstone) are likely to have evolved under low nutrient inputs, and
are therefore considered to be more sensitive to increased nutrient inputs than wetlands in
landscapes faced with less severe nutrient limits.
Method: This assessment is based on existing geological maps for the area. Where the threat of
nutrients is high or very high, it may be beneficial to assess current nutrient levels through nutrient
sampling.
4.4 Vulnerability of the HGM type to nutrient enrichment
Rationale: The less open (i.e. the more closed) the drainage system of a wetland (e.g. in the case of
an endorheic pan) and the less common natural flushing events, the more readily nutrients will be
able to accumulate within the system. Wetland systems with open drainage systems that are
characterized by regular flushing are therefore likely to be significantly less susceptible to nutrient
inputs. Floodplains are therefore likely to be least sensitive while pans, particularly those with a
closed drainage system, are likely to be most susceptible. Other HGM types are likely to be of
intermediate sensitivity as detailed in Table 5.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 5.

Preliminary Guideline for the Determination of Buffer Zones 2014
123
4.5 Extent of open water, particularly where the substrate is non-muddy
Rationale: Nutrient enrichment stimulates plant growth, potentially changing the composition of
naturally occurring vegetation. Areas of open water, which generally support a higher diversity of
submerged aquatic plants and fauna, are regarded as more sensitive than wetland areas with very
shallow water. In addition, submerged aquatic plants and aquatic fauna are generally severely
affected by increased nutrients.
Method: This assessment is informed by a rapid site assessment to estimate the average extent of
open water. Where possible, this assessment should be supplemented with orthophoto maps or
aerial photographs that can be used to better understand the relative extent of open water habitat.
4.6 Sensitivity of the vegetation to increased availability of nutrients
Rationale: An area that is already dominated by tall, dense vegetation has a low sensitivity because
it is much less likely to be overgrown by species, e.g. Typha capensis, which are well suited to
responding to increased nutrients. In contrast short and/or sparse vegetation may easily be
overgrown by such species. Naturally high plant species richness may further add to the sensitivity
of the vegetation to compositional and structural change as a result of the increased availability of
nutrients, which stimulates plant growth of specific species.
Method: This assessment is based on a rapid observation of the vegetation characteristics in the
HGM unit below the area of planned development. Note must be made of the height of natural
vegetation and diversity of indigenous vegetation. Occurrence of alien invasive species should not
be considered.
Note: Although little work has been done on the growth response of individual species to nutrients in
South Africa, numerous studies have been undertaken in North America. Information on the
response of many individual species to nutrients can be obtained for the National Database of
Wetland Plant Tolerances at:
http://www.epa.gov/owow/wetlands/bawwg/publicat.html#database1
5. Sensitivity to increases in toxic contaminants (including toxic metal ions (e.g. copper,
lead, zinc), toxic organic substances (reduces oxygen), hydrocarbons and pesticides) from
lateral inputs
Table 6. Wetland characteristics affecting the sensitivity of the water resource to increase inputs of
toxic substances from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Perimeter to area ratio High (>1500
m per ha) Moderately
high Intermediate (e.g.
1000 m per ha) Moderately
low Low (<500
m per ha)
Vulnerability of the HGM
type to toxic inputs
Depression –
endorheic,
Flat
Depression
– exhoreic
Hillslope seep,
Valley head seep,
Unchannelled
valley bottom
Channelled
valley-
bottom
Floodplain
wetland
Sensitivity of the
vegetation to increased
toxic inputs
High (high
natural
diversity)
Moderately
high
Intermediate (e.g.
moderate natural
plant diversity)
Moderately
low
Low (e.g.
low natural
diversity)

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5.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to toxic inputs. Large wetlands
have a greater inherent buffer capacity and are therefore less likely to be affected by changes in
lateral toxic inputs than small wetlands where moderate changes in toxic inputs could have a
substantial impact on wetland biota.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
5.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral toxic inputs. Long, thin wetlands are therefore
regarded as more susceptible than round or oval systems that would be less affected by edge
impacts that are likely to be felt most notably on the periphery where toxics enter the wetland.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter:area ratio. Use this to place the wetland into one of three classes
indicated.
5.3 Vulnerability of the HGM type to toxic inputs
Rationale: The less open (i.e. the more closed) the drainage system of a wetland (e.g. in the case of
an endorheic pan) and the less common natural flushing events, the more readily toxics will be able
to accumulate within the system. Wetland systems with open drainage systems that are
characterized by regular flushing are therefore likely to be significantly less susceptible to toxic
inputs. Floodplains are therefore likely to be least sensitive while pans, particularly those with a
closed drainage system, are likely to be most susceptible. Other HGM types are likely to be of
intermediate sensitivity as detailed in Table 6.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 6.
5.4 Sensitivity of the vegetation to toxic inputs
Rationale: Most plant species are relatively tolerant to toxic contaminants, with shifts in the
composition of the plant community in response to toxic contaminants not widely documented
(Sheldon et al., 2003). Despite the lack of reported responses of plants to toxic contaminants, the
potential of impacts occurring is likely to be higher in naturally diverse (typically un-impacted)
systems. The diversity of wetland vegetation is therefore used as a surrogate for the sensitivity of
wetland vegetation to toxic inputs.
Method: This assessment is based on a rapid observation of the vegetation characteristics in the
HGM unit below the area of planned development. Note must be made of the diversity of
indigenous vegetation. Occurrence of alien invasive species should not be considered.

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6. Sensitivity to changes in acidity (pH) from lateral inputs
Table 7. Wetland characteristics affecting the sensitivity of the water resource to changes in acidity
from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Perimeter to area ratio High (>1500
m per ha)
Moderately
high
Intermediate
(e.g. 1000 m
per ha)
Moderately
low
Low (<500
m per ha)
Vulnerability of the HGM
type to changes in pH
Depression –
endorheic,
Flat
Depression –
exhoreic
Hillslope seep,
Valley head
seep,
Unchannelled
valley bottom
Channelled
valley-bottom
Floodplain
wetland
Sensitivity of the
vegetation to changes in
acidity
High (high
natural
diversity)
Moderately
high
Intermediate
(e.g. moderate
natural plant
diversity)
Moderately
low
Low (e.g.
low natural
diversity)
Natural wetness regimes
Dominated
by
temporarily
saturated
soils
Mix of
seasonal and
temporarily
saturated
soils
Dominated by
seasonally
saturated soils
Mix of
permanently
and
seasonally
saturated
soils
Dominated
by
permanently
saturated
soils
6.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to toxic inputs. Large wetlands
have a greater inherent buffer capacity and are therefore less likely to be affected by changes in pH
in influent water than small wetlands where moderate changes in toxic inputs could have a
substantial impact on wetland biota.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
6.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral inputs. Long, thin wetlands are therefore
regarded as more susceptible than round or oval systems that would be less affected by edge
impacts that are likely to be felt most notably on the periphery where toxics enter the wetland.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter:area ratio. Use this to place the wetland into one of three classes
indicated.
6.3 Vulnerability of the HGM type to changes in pH
Rationale: The less open (i.e. the more closed) the drainage system of a wetland (e.g. in the case of
an endorheic pan) and the less common natural flushing events, the more likely that pH levels will

Preliminary Guideline for the Determination of Buffer Zones 2014
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change in response to lateral impacts. Wetland systems with open drainage systems that are
characterized by regular flushing are therefore likely to be significantly less susceptible. Floodplains
are therefore likely to be least sensitive while pans, particularly those with a closed drainage
system, are likely to be most susceptible. Other HGM types are likely to be of intermediate
sensitivity as detailed in Table 7.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 7.
6.4 Sensitivity of the vegetation to changes in acidity
Rationale: pH is reportedly critical in determining the distribution of plants in wetlands, by altering
the availability of some inorganic nutrients and carbon and increasing the toxicity of heavy metals
such as aluminium and manganese (Sheldon et al. (2003). Changes in acidity are likely to affect
wetland plants differently, depending on the sensitivity of specific species. The diversity of
indigenous wetland vegetation is likely to provide a useful surrogate for the sensitivity of wetland
vegetation to changes in acidity.
Method: This assessment is based on a rapid observation of the vegetation characteristics in the
HGM unit below the area of planned development. Note must be made of the diversity of
indigenous vegetation. Occurrence of alien invasive species should not be considered.
6.5 Natural wetness regimes
Rationale: Generally permanently saturated/flooded areas, which would support anaerobic soil
conditions, are better buffered than temporarily saturated soils. Seasonally saturated areas are
probably intermediate.
Method: The level of wetness can be determined by inferring level of wetness from soil morphology
(described based on visual observations of soil samples extracted with a Dutch screw auger to a
depth of 0.5 m) using the guidelines given in DWAF (2005). Knowledge of the hydric status of
wetland plants can also provide a useful indication of wetness regimes in untransformed wetland
areas.

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7. Sensitivity to changes in concentration of salts (salinization) from lateral inputs.
Table 8. Wetland characteristics affecting the sensitivity of the water resource to changes in acidity
from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large (>300
ha)
Perimeter to area ratio High (>1500
m per ha)
Moderately
high
Intermediate
(e.g. 1000 m
per ha)
Moderately
low
Low (<500 m
per ha)
Vulnerability of the
HGM type to changes in
salinity
Depression –
endorheic,
Flat
Depression –
exhoreic
Hillslope
seep, Valley
head seep,
Unchannelled
valley bottom
Channelled
valley-
bottom
Floodplain
wetland
Natural salinity levels - - Naturally low
saline levels
Intermediate
salinity
levels
Naturally
saline
systems
Sensitivity of the
vegetation to changes
in salinity
High (high
natural
diversity)
Moderately
high
Intermediate
(e.g.
moderate
natural plant
diversity)
Moderately
low
Low (e.g. low
natural
diversity)
7.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to lateral inputs. Large wetlands
have a greater inherent buffer capacity and are therefore less likely to be affected by increases in
salt concentrations in influent water than small wetlands where moderate changes in salinity could
have a substantial impact on wetland biota.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
7.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral inputs. Long, thin wetlands are therefore
regarded as more susceptible than round or oval systems that would be less affected by edge
impacts that are likely to be felt most notably on the periphery where toxics enter the wetland.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter:area ratio. Use this to place the wetland into one of three classes
indicated.
7.3 Vulnerability of the HGM type to changes in pH
Rationale: The less open (i.e. the more closed) the drainage system of a wetland (e.g. in the case of
an endorheic pan) and the less common natural flushing events, the more likely that salinity levels
will change in response to lateral impacts. Wetland systems with open drainage systems that are
characterized by regular flushing are therefore likely to be significantly less susceptible. Floodplains

Preliminary Guideline for the Determination of Buffer Zones 2014
128
are therefore likely to be least sensitive while pans, particularly those with a closed drainage
system, are likely to be most susceptible. Other HGM types are likely to be of intermediate
sensitivity as detailed in Table 8.
Method: Assign a sensitivity score based on the grouping of different HGM types in Table 8.
7.4 Natural salinity levels
Rationale: Biota that inhabit naturally saline wetlands (e.g. those associated with estuaries or pans
with naturally high salt levels) are adapted to tolerating salt levels that would kill most other wetland
species. Inland wetlands characterized by naturally low saline concentrations are however
anticipated to be far more susceptible.
Method: For wetlands with naturally high salt levels, the sensitivity score is refined downwards.
7.5 Sensitivity of the vegetation to changes in acidity
Rationale: In general, high concentrations of soluble salts are lethal to freshwater plants, and lower
concentrations may impair growth (Rending & Taylor, 1989 cited in Sheldon et al., 2003). Woody
plants also tend to be less tolerant than herbaceous plants because they do not have mechanisms
for removing salt, other than accumulating salts in leaves and subsequently dropping them (Adamus
et al. 2001). It can be expected that the plant community in a wetland will therefore change to one
dominated by salt-tolerant plants when additional salts are introduced. The diversity of wetland
vegetation is likely to provide a useful surrogate for the sensitivity of wetland vegetation to changes
in acidity.
Method: This assessment is based on a rapid observation of the vegetation characteristics in the
HGM unit below the area of planned development. Note must be made of the diversity of
indigenous vegetation. Occurrence of alien invasive species should not be considered.
8. Sensitivity to changes in water temperature from lateral inputs
Table 9. Wetland characteristics affecting the sensitivity of the water resource to changes water
temperature from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate (51-300 ha) Large
(>300 ha)
Perimeter to area ratio High (>1500
m per ha)
Moderately
high
Intermediate (e.g.
1000 m per ha)
Moderately
low
Low (<500
m per ha)
Extent of open water High (>9%
of the area)
Moderately
High (7-9%) Moderate (4-6%) Low
(0.5-3%)
Very low
(<0.5%)
Mean Annual
Temperature MAT Zone 1
(Coolest)
MAT Zone
2 MAT Zone 3 MAT Zone
4
MAT Zone
5
(Warmest)

Preliminary Guideline for the Determination of Buffer Zones 2014
129
8.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to lateral inputs. Large wetlands
have a greater inherent buffer capacity and are therefore less likely to be affected by changes in
temperature in influent water than small wetlands where moderate changes in salinity could have a
substantial impact on wetland biota.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).
8.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral inputs. Long, thin wetlands are therefore
regarded as more susceptible than round or oval systems that would be less affected by edge
impacts that are likely to be felt most notably on the periphery where toxics enter the wetland.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter: area ratio. Use this to place the wetland into one of three classes
indicated.
8.3 Extent of open water
Rationale: Submerged aquatic plants and aquatic fauna are generally more severely affected by
changes in water temperature, given the fact that they are contained entirely within the water
column. Therefore, open water areas are considered more sensitive to changes in water
temperature from lateral inputs than emergent vegetation areas.
Method: This assessment is informed by a rapid site assessment to estimate the average extent of
open water. Where possible, this assessment should be supplemented with orthophoto maps or
aerial photographs that can be used to better understand the relative extent of open water habitat.
8.5 Mean Annual Temperature
Rationale: Rivers characterised by cooler water are more sensitive to thermal pollution than rivers
with higher temperatures. Rivers situated in cooler regions are likely to be more sensitive to
changes in water temperature (Figure 3).
Method: At a desktop level of assessment, determine the mean annual temperature zone that
characterises the catchment.

Preliminary Guideline for the Determination of Buffer Zones 2014
130
Figure 3. Mean annual temperature separated into five temperature zones, based on five equal
quantiles) (Data from Schulze et al., 2007)
9. Sensitivity to changes in pathogens from lateral inputs
Table 10. Wetland characteristics affecting the sensitivity of the water resource to increased
pathogen inputs from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size Small (<0.5
ha) 0.5-5 ha (6-50)
Intermediate
(51-300
ha)
Large (>300
ha)
Perimeter to area ratio High (>1500
m per ha)
Moderately
high
Intermediate
(e.g.1000 m per
ha)
Moderately
low
Low (<500 m
per ha)
Level of domestic use High Moderately
high Moderate Moderately
low Low
9.1 Overall size
Rationale: Wetland size provides a broad surrogate for sensitivity to lateral inputs. Large wetlands
have a greater inherent buffer capacity and are therefore likely to be affected by increases in
pathogen inputs to a lesser degree than small wetlands where moderate increases in pathogen
inputs could lead to rapid increases in pathogen levels.
Method: Determine the approximate area of the wetland (HGM unit) being assessed using available
tools (e.g. GIS).

Preliminary Guideline for the Determination of Buffer Zones 2014
131
9.2 Perimeter to area ratio
Rationale: The greater the perimeter to area ratio, the greater the likelihood that much of the
wetland could potentially be impinged upon by lateral inputs. Long, thin wetlands are therefore
regarded as more susceptible than round or oval systems that would be less affected by edge
impacts that are likely to be felt most notably on the periphery where toxics enter the wetland.
Method: Determine the approximate perimeter of the wetland being assessed and divide this by the
area to obtain a perimeter: area ratio. Use this to place the wetland into one of three classes
indicated.
9.3 Level of domestic use
Rationale: The higher the level of domestic water use, the higher the threat of increasing pathogen
levels to water users.
Method: Based on an evaluation of land use around the wetland and discussions with local
stakeholders, establish the level of domestic water use (including recreational use).
10. References
Adamus, P.R., Danielson, T.J, Gonyaw, A. (2001). Indicators for monitoring biological integrity of
inland freshwater wetlands: A survey of North American Technical Literature (1990-2000). Office of
Water, US Environmental Protection Agency, Washington D.C.
Department of Water affairs and Forestry (2005). A practical field procedure for identification and
delineation of wetland and riparian areas. Edition 1, September 2005. DWAF, Pretoria.
Ellery WN, Grenfell M, Grenfell S, Kotze DC, McCarthy TS, Tooth S, Grundling PL, Beckedahl H, Le
Maitre D and Ramsay L, 2008. WET-Origins: Controls on the distribution and dynamics of wetlands
in South Africa. WRC Report No TT 334/08. Water Research Commission, Pretoria.
Macfarlane, D., Kotze, D.C., Ellery, W.N., Walters, D., Koopman, V., Goodman, P., Goge, C. (2007).
Wet-health: a technique for rapidly assessing wetland health. WRC Report No TT 340/08, Water
Research Commission, Pretoria.
Pyke, C.R., Havens, K.J. (1999). Distribution of the invasive reed Phragmites australis relative to
sediment depth in a created wetland. Wetlands 19, 282-287.
Rendig, V.V., Taylor, H.M. (1989). Principles of soil-plant interrelations. McGraw-Hill, New York,
USA.
Reinelt, R.E., Taylor, B.L. (2001). Effects of watershed development on hydrology. In: Azous, A.L.,
Horner, R.R. (2001). Wetlands and Urbanization: implications for the future. Lewis Publishers, Boca
Raton, Florida.
Schulze, R.E. (ed) (1989). ACRU: Background concepts and theory. ACRU Report No. 36,
Department of Agricultural Engineering, University of Natal, Pietermaritzburg, RSA.
Schulze R.E. (ed) (2007). South African Atlas of Climatology and Agrohydrology. WRC Report No.
1489/1/06. Water Research Commission, Pretoria.

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132
Schulze, R.E. (2010). Mapping Hydrological Soil Groups over South Africa for Use with the SCS –
SA Design Hydrograph Technique: Methodology and Results. School of Agricultural, Earth and
Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Schulze, R.E., Schmidt, E.J., Smithers, J.C. (1992). PC-based SCS flood estimates for small
catchments in Southern Africa. Department of Agricultural Engineering, University of Natal,
Pietermaritzburg, RSA.
Sheldon, D., Hruby, T., Johnson, P., Harper, K., McMillan, A., Stanley, S., Stockdale, E. (2003).
Freshwater wetlands in Washington State. Volume 1: A synthesis of the science. Washington
Department of Ecology, Washington D.C.
Wang, S.C., Jurik, T.W., van der Valk, A.G. (1994). Effects of sediment load on various stages in
the life and death of cattail (Typhax glauca). Wetlands 14, 166-173.

Preliminary Guideline for the Determination of Buffer Zones 2014
133
1
1
1 1 1
1
1 1
1 1
1 1
2 2
2
2 4
3
3
Annexure 13 – Guideline for assessing the sensitivity of rivers and
streams to impacts from lateral land use inputs
The focus of this assessment is on the sensitivity of streams and rivers to lateral impacts rather than
broader catchment impacts. The sensitivity of the river as an integrated ecosystem, rather than the
sensitivity of important biota is assessed here. Where important biodiversity elements are present,
additional protection measures need to be identified in line with the sensitivity of focus species to
threats identified. Other existing legislated frameworks, policies, etc. should be considered to afford
protection to species.
Indicators have been defined in order to assess the sensitivity of rivers to common threats posed by
lateral land-use impacts. The indicators were scored relative to a typical “reference” river of
intermediate sensitivity and are used to calculate a sensitivity score and associated class for each
threat type under consideration.
1. Sensitivity to changes in water quantity (volumes of flow) from lateral inputs
Table 1. Stream / river characteristics affecting the sensitivity of the water resource to changes in
the volumes of inputs from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Stream order 1s
t
order 2n
d
order 3r
d
order 4
th
order > 5
th
order
Channel width < 1 m 1-5 m 5-10 m 10-20 m > 20 m
Perenniality
Perennial
systems
Ephemeral
systems
Episodic
systems
1.1. Stream order
Rationale: Small streams are likely to be more sensitive to changes in quantity of water generated
within the catchment than larger systems. As a result small contributions of water from lateral inputs
will have a much greater effect on streams and rivers fed by small catchments as opposed to those
fed by large catchments. Stream ordering is a useful surrogate for determining the relative size of
catchments and is used here as a method for estimating catchment size for a particular section of
river.
Method: Using the Horton-
Strahler stream ordering
method, determine the stream
order using 1:50 000 rivers
coverage or 1:50 000
topographical maps to
ascertain the stream order for
the reach of river. The
following diagram illustrates
how stream orders are
incrementally determined
relative to catchment position.
This is a desktop procedure where stream order is manually determined using 1:50 000

Preliminary Guideline for the Determination of Buffer Zones 2014
134
topographical maps or rivers coverage in GIS. Alternatively, numbering may be derived using a GIS
algorithm.
1.2. Channel width
Rationale: River width is a useful measure of the size of a river and therefore provides an indication
of a river’s sensitivity to changes in flow volumes from lateral inputs. River widths are based on site
specific measurements and therefore accounts for any possible variations of the size of rivers that
may have the same stream order (as determined in the previous step).
Method: Widths of streams are grouped into broad categories, obviating the need for detailed site-
based measurements. Width is taken as the distance between active channel banks which can be
established during site visits or estimated based on measurements made from appropriate remote
imagery such as that available on Google Earth.
1.3. Perenniality
Rationale: The perenniality of a river affects how sensitive the water resource will be to changes in
water inputs. In this regard, perennial systems (particularly small streams) are regarded as most
sensitive as habitat and biota is adapted to constant flow regimes. Ephemeral systems are
regarded as moderately sensitive as organisms are adapted to periods of no flow. Episodic streams
are naturally highly variable and usually associated with low MAR and are therefore adapted to no-
flow conditions. Additional reductions in flow will simply increase the variability or duration of no-
flow conditions. The following classes are used to define perenniality; non-perennial (seasonal), and
non-perennial (intermittent).
Method: At a desktop level, perenniality may be interpreted from 1:50 000 topographical sheets
where rivers indicated with a solid line are considered to be perennial systems and dotted lines
represent non-perennial rivers (i.e. seasonal and intermittent). Distinction between seasonal and
intermittent rivers is made where the former consists of river systems that flow for extended periods
during the wet seasons/s (generally between 3 to 9 months), at intervals varying from less than a
year to several years (Ollis et al., 2013). Intermittent rivers flow for a relatively short time of less
than one season’s duration (i.e. less than approximately 3 months) at intervals varying from less
than a year to several years (Ollis et al., 2013). The perenniality of the watercourse can typically be
identified by checking the stream bed for signs of wetness (linked to groundwater interaction) and
the presence of hydric plant species in the active channel. In the case of episodic streams, signs of
wetness and hydric plant species are typically absent.
2. Sensitivity to changes in patterns of flow (frequency, amplitude, direction of flow) from
lateral inputs
Table 2. Stream / river characteristics affecting the sensitivity of the water resource to changes in
the patterns of flow from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Stream order 1s
t
order 2n
d
order 3r
d
order 4
th
order > 5
th
order
Average catchment slope <3% 3-5% 6-8% 9-11% >11%
Inherent runoff potential
of catchment soils Low (A & A/B) Mod. Low (B) Moderate (B/C) Mod. High (C) High (C/D & D)

Preliminary Guideline for the Determination of Buffer Zones 2014
135
2.1. Stream order
Rationale: Similar to Section 1.1, streams with small catchments are generally more sensitive to
changes in patterns of flow as they are to changes in quantity of water generated within the
catchment. As a result small contributions of water from lateral inputs will have a much greater
effect on a small streams as opposed to those associated with larger catchments. For example, a
volume of stormflow generated from an impervious area (e.g. parking areas and roofs) adjacent to a
river of a small catchment will have a more dramatic effect on the natural hydrograph than a river
draining a large catchment. The diagram below illustrates this example of the relative sensitivity of
small and large catchments to a similar volume of effluent water (note the scale of river discharge is
not in proportion).
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
2.2. Average catchment slope
Rationale: Catchment topography is a key driver of hydrological responses in the landscape. Slope
is therefore particularly important in terms of encouraging surface runoff in response to rainfall
events where steeper slopes generally produce higher surface runoff compared to flat/moderate
slopes. The result of higher surface runoff is a natural tendency for “flashy” flow properties in rivers.
Rivers that are naturally “flashy” are likely to be less sensitive to impacts on patterns of flow from
lateral inputs.
Method: Average slope can be roughly calculated simply from available topographic maps or from
GIS datasets or Google Earth information. This is done by first taking elevation readings from (i) the
upper-most point of the catchment and (ii) the site being assessed and calculating the altitudinal
change. The distance between these points is then measured and average slope estimated by
dividing the altitudinal change by the distance from the upper reaches of the catchment.
2.3. Inherent runoff potential of catchment soils
Rationale: The ability of a catchment to partition runoff into surface and sub-surface flow
components depends largely on prevailing catchment conditions, which may be the result of both
natural and anthropogenic processes. Soils are a key natural regulator of catchment hydrological
Small
catchment
hydrograph
Large
catchment
hydrograph
Effluent discharge
Time
River
discharge

Preliminary Guideline for the Determination of Buffer Zones 2014
136
response due the capacity that soils have for absorbing, retaining and releasing/redistributing water
(Schulze, 1989). Catchments dominated with deep, well-drained soils generally have high rates of
permeability and thus a greater proportion of rainfall can infiltrate into the soil profile. Consequently
catchments with highly permeable soils therefore have a much lower runoff potential compared to
soils with a low permeability (e.g. clay soils). As such, rivers fed by catchments characterized by
higher permeabilities are characterized by less flashy flows than those fed by catchments
characterized by low permeabilities. Rivers with naturally flashy flows are therefore regarded as
less sensitive to changes in the pattern of lateral water inputs (e.g. increased runoff during heavy
rains) than those characterised by less variable flow regimes.
Method: The Soil Conservation Services method for Southern Africa (SCS-SA) uses information of
hydrologic soil properties to estimate surface runoff from a catchment (Schulze et al., 1992). With
reference to the SCS-SA (Table 3), determine the appropriate hydrological soil group that defines
the entire catchment based on available soils information. Such information is obtainable from the
Land Type maps of South Africa, which includes information on soil texture.
Table 3. Runoff potential classes (after Schulze et al., 1992)
LOW RUNOFF
POTENTIAL MODERATELY LOW
RUNOFF POTENTIAL MODERATELY HIGH
RUNOFF POTENTIAL HIGH RUNOFF
POTENTIAL
Soil Group A:
Infiltration is high and
permeability is rapid.
Overall drainage is
excessive to well-
drained.
Soil Group B:
Moderate infiltration
rates, effective depth
and drainage.
Permeability slightly
restricted.
Soil Group C:
Infiltration rate is slow
or deteriorates rapidly.
Permeability is
restricted.
Soil Group D: Very
slow infiltration and
severely restricted
permeability. Includes
soils with high shrink-
swell potential.
Figure 1. Distribution of SCS soil groups A to D over South Africa at a spatial resolution of Land
Type polygons (Schulze 2010)

Preliminary Guideline for the Determination of Buffer Zones 2014
137
3. Sensitivity to changes in sediment inputs and turbidity from lateral inputs
Table 4. Stream / river characteristics affecting the sensitivity of the water resource to changes in
sediment inputs and turbidity from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 510 m 10-20 m > 20 m
Longitudinal river zonation Upper foothill
river
Transitional
river
Mountain
stream
Lower foothill
river
Lowland
river
Inherent erosion potential (K
factor) of catchment soils < 0.13 0.13-0.25 0.25-0.50 0.50-0.70 > 0.70
Average catchment slope <3% 3-5%
6-8% 9-11% >11%
Inherent runoff potential of
catchment soils Low (A & A/B) Mod. Low (B) Moderate
(B/C) Mod. High (C) High (C/D
& D)
3.1. Channel width
Rationale: Stream size provides a broad surrogate for sensitivity to sediment inputs. Large rivers
have a greater inherent buffer capacity and are therefore less likely to be affected by changes in
lateral sediment inputs than small streams where moderate changes in sediment inputs could have
a substantial impact on turbidity levels.
Method: See method in 1.2 for estimating channel width
3.2. Longitudinal river zonation
Rationale: Whether a river is characterised as an upland or lowland river depends on various
geomorphological characteristics driven by factors such as topography and hydrology. These
characteristics in turn affect the rates of sediment transport and deposition taking place within a river
along its longitudinal length. Rivers situated in the upper reaches of catchments tend to be
“sediment-free” due to effective removal mechanisms resulting from river flow rates whilst rivers
situated in the lower reaches are naturally driven by sediment deposition (notable of river
floodplains). Intermediate river sections, however, are arguably more sensitive to sediment inputs
than headwater and lowland sections due to limited abilities for sediment removal as well as
reasonably high potential for deposition.
Method: At a desktop level33, determine the suitable geomorphological classification of the river
based on the classification system of Rowntree and Wadeson (2000); establish which of the
following categories the river would be classed as:
• Mountain stream – Steep to very steep-gradients where gradients exceed 0.04 (Includes
Mountain headwater streams). Substrates are generally dominated by bedrock and
boulders, with cobbles or coarse gravels in pools.
• Transitional River – moderately steep stream dominated by bedrock and boulders; reach
types include plain-bed, pool-riffle or pool-rapid; usually in confined or semi-confined valley.
Characteristic gradient is 0.02-0.039.
33 Geomorphological categories have been mapped at a national scale using the 1:500 000 rivers of South Africa. These
maps may be obtained from the Department of Water Affairs’ Water Quality Services
(http”//www.dwa.gov.za/iwqs/gis_data/rivslopes/rivprofil.asp) . The NFEPA rivers map (available via a link from
http://bgis.sanbi.org/nfepa/NFEPAmap.asp) also provides longitudinal river zonation information for mainstem rivers
and larger tributaries.

Preliminary Guideline for the Determination of Buffer Zones 2014
138
• Upper Foothill River – moderately steep, cobble-bed or mixed bedrock-cobble bed
channels, with plain-bed, pool-riffle or pool-rapid reach types; length of pools and
riffles/rapids is similar. Characteristic gradient is 0.005-0.019.
• Lower Foothill River – lower-gradient, mixed-bed alluvial channel with sand and gravel
dominating the bed and may be locally bedrock controlled; reach types typically include pool-
riffle or pool-rapid, with sand bars common in pools; pools are of significantly greater extent
than rapids or riffles. Characteristic gradient is 0.001-0.005.
• Lowland River – low-gradient, alluvial fine-bed channels, which may be confined, but fully
developed meandering pattern within a distinct floodplain develops in unconfined reaches
where there is increased silt content in bed or banks. Characteristic gradient is
0.0001-0.001.
Rapid site assessments are recommended in addition to desktop determination procedures in order
to verify site specific river characteristics. The aforementioned features should be considered when
conducting site assessments, i.e. typically channel substrates, deposition features, etc.
3.3. Inherent erosion potential of catchment soils
Rationale: Soils vary in terms of processes such as soil particle detachment and transport caused
by raindrop impact and surface runoff. Different soils also have different rates of infiltration into the
soil profile. Soil characteristics such as these therefore determine the erosive potential of different
soils. Rivers driven by soils with characteristically high erodibility potential, are characterized by
naturally higher sediment inputs and are therefore considered less sensitive to additional sediment
inputs than river catchment systems dominated by soils with a low erodibility potential.
Method: Using the South African Atlas of Climatology and Agrohyrology (Schulze, 2007) determine
the soil erodibility factor for the general catchment area within which the river reach occurs
according to the corresponding soil erodibility classes and K-factors (Figure 2).

Preliminary Guideline for the Determination of Buffer Zones 2014
139
Figure 2. Soil erodibility (K-Factor) (Schulze et al., 2007)
The following are used to define soil erodibility according to the prevailing soil K-factor.
SOIL ERODIBILITY CLASS SOIL K-FACTOR
Very high > 0.70
High 0.50-0.70
Moderate 0.25-0.50
Low 0.13-0.25
Very low < 0.13
Note: For catchments characterised by more than one area of differing K-factors, an average area-
weighted K-factor for the catchment needs to be determined.
3.4. Average catchment slope
Rationale: Given that slope is a key driver of catchment hydrological response (c.f. Section 2.2) it is
also has a significant influence on secondary factors such as soil erosion. Catchments that are
affected by heavy soil erosion are expected to have high rates of sedimentation within the rivers. As
a consequence, rivers draining catchments characterised by steep topography are likely to
experience higher levels of sedimentation due to higher erosion.
Method: Refer to Method 2.2 when calculating average catchment slope.

Preliminary Guideline for the Determination of Buffer Zones 2014
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3.5. Inherent runoff potential of catchment soils
Rationale: Refer to Rationale 2.3.
Method: Using the method from 2.3, determine the appropriate hydrological soil group that defines
the entire catchment based on available soils information.
4. Sensitivity to increased inputs of nutrients (phosphate, nitrite, nitrate) from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 510 m 10-20 m > 20 m
Stream order 1st order 2nd order 3rd order 4th order > 5th order
Retention time
Generally
free-
flowing
(lotic)
Generally
slow
moving
(lentic)
Inherent level of nutrients in
the landscape: Is the
river/stream and its catchment
underlain by sandstone?
Yes Partially No
Inherent erosion potential (K
factor) of catchment soils < 0.13 0.13-0.25 0.25-0.50 0.50-0.70 > 0.70
4.1. Channel width
Rationale: Stream size provides a broad surrogate for sensitivity to inputs of various pollutants.
Large rivers have a greater inherent buffer capacity and are therefore less likely to be affected by
changes in lateral pollutant inputs than small streams where moderate changes in pollutant inputs
could have a substantial impact on water quality.
Method: See method in 1.2 for estimating channel width.
4.2. Stream order
Rationale: Small catchments are generally more sensitive to pollutant loading compared to larger
systems where smaller systems have a much smaller inherent potential to dilute sources of
pollutants. As a result a source of pollution from lateral inputs will have a much greater effect on a
small catchment as opposed to a large catchment. For example, a 2 ML discharge of effluent water
from a wastewater treatment works into a small catchment will have a much greater impact in terms
of nutrient pollution than a large catchment system.
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
4.3. Retention time
Rationale: Rivers dominated by pools and slow flowing sections have a greater tendency for
nutrients to accumulate and thus for higher impacts to occur (such as increased algal growth) due to
higher retention times. Thus rivers characterised by higher retention times are more sensitive to
nutrient loads received from lateral inputs.
Method: Assess whether the section of river is generally free-flowing (lotic) or slow moving (lentic).

Preliminary Guideline for the Determination of Buffer Zones 2014
141
4.4. Inherent level of nutrients in the landscape
Rationale: Increased nutrient availability in naturally nutrient-poor systems allows grasses and
common opportunistic plants to outcompete rare plants that are adapted to nutrient-poor conditions
(Sheldon et al., 2003). Rivers located in landscapes which are inherently low in nutrients (notably,
those dominated by sandstone) are likely to have evolved under low nutrient inputs, and are
therefore considered to be more sensitive to increased nutrient inputs than streams / rivers in
landscapes faced with less severe nutrient limits.
Method: This assessment is based on existing geological maps for the area. Where the threat of
nutrients is high or very high, it may be beneficial to assess current nutrient levels through nutrient
sampling.
4.5. Inherent erosion potential of catchment soils
Rationale: Soil erosion is regarded as a major contributor to Phosphorous levels in streams. As
such, streams fed by catchments with high erodibility are likely to have higher inherent Phosphate
loadings that where catchments are characterized by low soil erodibility.
Method: Using the method from 3.3.
5. Sensitivity to increases in toxic contaminants (including toxic metal ions (e.g. copper,
lead, zinc), toxic organic substances (reduces oxygen), hydrocarbons and pesticides)
from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 5-10 m 10-20 m > 20 m
Stream order 1st order 2nd order
1-5 m 3rd order 4th order > 5th order
Inherent erosion potential (K
factor) of catchment soils < 0.13 0.13-0.25 0.25-0.50 0.50-0.70 > 0.70
Inherent runoff potential of
catchment soils Low (A &
A/B)
Mod. Low
(B)
Moderate
(B/C)
Mod. High
(C)
High (C/D
& D)
5.1. Channel width
Rationale: See Rationale 4.1
Method: See method in 1.2 for estimating channel width.
5.2. Stream order
Rationale: See Rationale 4.2.
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
5.3. Inherent erosion potential of catchment soils (heavy metals only)
Rationale: Concentrations of heavy metals in rivers are derived naturally by the weathering of
underlying geological formations resulting in a natural enrichment of heavy metals contained in
weathered sediments. Therefore catchments with a high erodibility potential are likely to experience

Preliminary Guideline for the Determination of Buffer Zones 2014
142
high levels of heavy metal enrichment through geological weathering. Catchments that are driven
naturally by heavy metal enrichments are considered less sensitive than catchments with low
weathering (and thus low enrichment).
Method: Refer to Method 3.3 to determine the appropriate soil erodibility classes and K-factors.
5.4. Inherent runoff potential of catchment soils
Rationale: Toxic contamination in rivers is driven naturally by processes such as surface runoff, a
key factor resulting in the transport of various toxic contaminants from the land and into rivers.
Based on the prevailing soils, catchments with a high runoff potential are more susceptible to toxic
contamination in the rivers than catchments with low runoff potential.
Method: Using the method from 2.3, determine the appropriate hydrological soil group that defines
the runoff potential for the entire catchment based on available soils information.
6. Sensitivity to changes in acidity (pH) from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 510 m 10-20 m > 20 m
Stream order 1st order 2nd order 3rd order 4th order > 5th order
Inherent buffering capacity
Pure
waters
with poor
pH
buffering
Neutral
pH
“Hard”
water rich
in bicarbo-
nate and
carbonate
ions or
naturally
acid
waters
high in
organic
acids34
6.1. Channel width
Rationale: See Rationale 4.1
Method: See method in 1.2 for estimating channel width
6.2. Stream order
Rationale: See Rationale 4.2.
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
34http://yosemite.epa.gov/r10/ecocomm.nsf/c6b2f012f2fd7f158825738b0067d20b/9a6226e464ecdb3f88256b5d0067
de0d/$FILE/chapter3.pdf

Preliminary Guideline for the Determination of Buffer Zones 2014
143
6.3. Inherent buffering capacity
Rationale: pH is determined by the concentration of hydrogen ions (H+). In very pure waters (i.e.
water containing no solutes) pH can change rapidly because the rate of change is determined by
the buffering capacity, which in turn is usually determined by the concentration of carbonate and
bicarbonate ions in the water. Consequently, pH in river water to some degree is driven naturally by
geological formations due to the dominance of bicarbonate and carbonate ions present in the
mineral composition of geological formations. At the opposite end of this scale, acid rivers
dominated by organic acids have an entirely different buffering system based on the presence of
those organic acids. This system is not well understood.
Method: At a desktop level determine whether the river system has a low buffering capacity and
thus sensitive to changes in pH according to the four broad geographical patterns as defined by Day
and King (1995).
7. Sensitivity to changes in concentration of salts (salinization) from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 510 m 10-20 m > 20 m
Stream order 1st order 2nd order 3rd order 4th order > 5th order
Underlying geographical
formations
Rock formations
characterised
with granite,
siliceous sand
and well-
leached soils
Primarily
Precambrian
formations
Primarily
Palaeozoic
and Mesozoic
sedimentary
rock
formations
7.1. Channel width
Rationale: See Rationale 4.1
Method: See method in 1.2 for estimating channel width
7.2. Stream order
Rationale: Salts tend to accumulate with downstream distance as salts are continuously added
through natural and anthropogenic sources and due to the fact that very little is removed through
natural processes.
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
7.3. Underlying geographical formations
Rationale: River water has natural salt concentrations that are a result of the dissolution of minerals
in rocks and soils; hence the natural contributions of the minerals vary according to geological
formations. As a result the concentrations of salts in river water are low where granite, siliceous
sand and well-leached soils prevail. Salt concentrations are higher where Precambrian formations
are present and highest for Palaeozoic and Mesozoic sedimentary rock formations.

Preliminary Guideline for the Determination of Buffer Zones 2014
144
Method: At a desktop level of assessment, determine the dominant geological formations that
characterise the catchment.
8. Sensitivity to changes in water temperature from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Stream order 1st order 2nd
order 3rd order 4th
order > 5th order
River depth to width ratio > 0.25 0.25-0.75 < 0.75
Mean Annual Temperature MAT Zone
1 (Coolest)
MAT
Zone 2 MAT Zone 3
MAT
Zone
4
MAT Zone 5
(Warmest)
Longitudinal river zonation Mountain
stream and
headwaters
Transitional
and upper
foothill rivers
Lower
foothill and
lowland
rivers
8.1. Stream order
Rationale: See Rationale 4.1.
Method: Refer to Method 1.1 to determine the stream order using the Horton-Strahler stream
ordering method.
8.2. River depth to width ratio
Rationale: Rivers that have a large depth to width ratio have a low thermal inertia and thus a low
capacity to absorb solar radiation compared to shallow systems. Systems with a low thermal inertia
are therefore more sensitive to changes in water temperature from lateral inputs, e.g. heated
industrial effluents.
Method: Determine the approximate depth and width of the river channel for the site and then
calculate the depth to width ratio (i.e. depth divided by width).
The following categories are used to represent the sensitivity of a river to changes in water
temperature based on the river’s thermal capacity:
• Large depth to width ratio: >0.75
• Medium depth to width ratio: 0.25-0.75
• Small depth to width ratio: < 0.25
8.3. Mean Annual Temperature
Rationale: Rivers characterised by cooler water are more sensitive to thermal pollution than rivers
with higher temperatures. Rivers situated in cooler regions are likely to be more sensitive to
changes in water temperature (Figure 3).
Method: At a desktop level of assessment, determine the mean annual temperature zone that
characterises the catchment.

Preliminary Guideline for the Determination of Buffer Zones 2014
145
Figure 3. Mean annual temperature separated into five temperature zones, based on five equal
quantiles) (Data from Schulze et al., 2007)
8.4. Longitudinal river zonation
Rationale: The position of a river relative to the landscape and its catchment affects the hydrological
processes that drive the river system. Hydrology, particularly flow rate, in turn affects the river’s
thermal regime due to influences on residence time thus the amount of solar radiation that can be
absorbed. Therefore headwater and mountain systems are likely to vary in temperature more
compared to slower flowing lowland rivers.
Geomorphological status also defines to some extent the concentration of suspended sediments
contained within the river which further influences river water temperature. Lowland rivers, because
of the accumulation of sediments and fines with downstream distance, tend to be more turbid than
rivers situated in the upper catchment reaches. Rivers with a high turbidity have a low albedo35 and
thus have a greater ability to absorb solar radiation rather than reflecting incoming solar rays. Thus
rivers that are naturally turbid are generally warmer and thus less sensitive to changes in river water
temperature caused by thermal pollution from lateral inputs.
Method: At a desktop level determine the geomorphological position of the river according to the
geomorphological classification system of Rowntree and Wadeson (2000) as outlined in Section 3.2.
These are grouped broadly into three classes, namely:
35 Is a measure of how strongly an object reflects light from light sources such as the sun.

Preliminary Guideline for the Determination of Buffer Zones 2014
146
• Mountain Headwater Streams and Mountain Streams – Steep to very steep-gradients
where gradients exceed 0.04. Substrates are generally dominated by bedrock and boulders,
with cobbles or coarse gravels in pools.
• Transitional and Upper Foothill Rivers – Moderately steep stream (characteristic gradient
is 0.005-0.04) dominated by bedrock, boulders and cobbles; reach types include plain-bed,
pool-riffle or pool-rapid.
• Lower Foothill and Lowland Rivers – lower-gradient (characteristic gradient is 0.0001-
0.005). Substrates range from mixed-bed alluvial channel with sand and gravel dominating
the bed to alluvial fine-bed channels. Reach types range from pool-riffle or pool-rapid, with
sand bars common in pools to fully developed meandering pattern within a distinct floodplain
and unconfined reaches where there is increased silt content in bed or banks.
9. Sensitivity to changes in pathogens from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Channel width < 1 m 1-5 m 510 m 10-20 m > 20 m
River depth to width ratio > 0.25 0.25-0.75 < 0.75
Level of domestic use High Moderately
high Moderate Moderately
low Low
9.1. Channel width
Rationale: See Rationale 4.1
Method: See method in 1.2 for estimating channel width
9.2. River depth to width ratio
Rationale: Increased exposure of pathogens to solar radiation results in higher inactivation rates
due to processes such as photo oxidative damage (Sinton et al., 2007). Thus river with higher
surface area to volume ratios have a greater potential for exposing pathogens to solar radiation, and
hence the greater amount of pathogenic inactivation. Rivers with small surface area to volume
ratios are considered to have a high sensitivity to pathogen influxes due to limited breakdown and
inactivation from sunlight exposure.
Method: Similar to Section 8.3, conduct a rapid site assessment to determine the approximate depth
and width of the river channel for the site and then calculate the depth to width ratio (i.e. depth
divided by width). For detailed assessments, refer to Method 8.3.
9.3. Level of domestic use
Rationale: The higher the level of domestic water use, the higher the threat of increasing pathogen
levels to water users.
Method: Based on an evaluation of land use around the river and discussions with local
stakeholders, establish the level of domestic water use (including recreational use).

Preliminary Guideline for the Determination of Buffer Zones 2014
147
10. References
Day, J.A., King, J.M., 1995. Geographical patterns and their origins in the dominance of major ions
in South African rivers. South African Journal of Aquatic Science 90: 299-306.
DWAF, 2005. A Practical Field Procedure for Identification and Delineation of Wetland and Riparian
areas. Edition 1, September 2005. Department of Water Affairs and Forestry, Pretoria.
Ollis, D., Snaddon, K., Job, N., Mbona, N., 2013. Classification system for wetlands and other
aquatic ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22.
South African National Biodiversity Institute, Pretoria.
Rowntree, K., Wadeson, R., 2000. The development of a geomorphological classification system for
the longitudinal zonation of South African rivers. South African Geographical Journal 82: 163-172.
SANBI, 2009. Further Development of a Proposed National Wetland Classification System for South
Africa. Primary Project Report. Prepared by the Freshwater Consulting Group (FCG) for the South
African National Biodiversity Institute (SANBI).
Schulze, R.E., 1989. ACRU: Concepts, background and theory. WRC Report No. 154/1/89. Water
Research Commission, Pretoria.
Schulze, R.E., (ed) 2007. South African Atlas of Climatology and Agro-hydrology. WRC Report No.
1489/1/06. Water Research Commission, Pretoria, RSA.
Schulze, R.E. (2010). Mapping Hydrological Soil Groups over South Africa for Use with the SCS –
SA Design Hydrograph Technique: Methodology and Results. School of Agricultural, Earth and
Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Schulze, R.E., Schmidt, E.J., Smithers, J.C., 1992. PC-based SCS flood estimates for small
catchments in Southern Africa. South Africa: Department of Agricultural Engineering, University of
Natal, Pietermaritzburg, RSA.
Sheldon, F., Boulton, A.J., Puckridge, J.T., 2003. Conservation value of variable connectivity:
aquatic invertebrate assemblages of channel and floodplain habitats of a central Australian arid-
zone river. Biological Conservation 103: 13-31.
Sinton, L., Hall, C., Braithwaite, R., 2007. Sunlight inactivation of Campylobacter jejuni and
Salmonella enterica, compared with Escherichia coli, in seawater and river water. Journal of Water
Health 5: 357-365.
WRC, 2004. Assessment of the South African Diatom Collection. WRC Report No. K8/508/2004.
Water Research Commission, Pretoria.

Preliminary Guideline for the Determination of Buffer Zones 2014
148
Annexure 14 – Guidelines for assessing the sensitivity of estuaries to
lateral land-use inputs
The focus of this assessment is on the sensitivity of estuaries to lateral impacts rather than broader
catchment impacts. The sensitivity of the overall estuary, rather than the sensitivity of important
biota is assessed. Where important biodiversity elements are present, additional protection
measures need to be identified in line with the sensitivity of focus species to threats identified.
Indicators have been defined in order to assess the sensitivity of estuaries to common threats posed
by lateral land-use impacts. These impacts include volume and timing of lateral water inputs,
sediment, nutrients & toxins and pathogen inputs from lateral inputs as well as changes in salt input
and temperature. The indicators were scored relative to a typical “reference” estuary of
intermediate sensitivity and are used to calculate a sensitivity score and associated class for each
threat type under consideration.
Sensitivity to changes in water quantity (volumes of flow) from lateral inputs
Table 1. Estuary characteristics affecting the sensitivity of the water resource to changes in the
volumes of inputs from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Perenniality of river inflows Intermittent
Seasonal Perennial
1.1 Estuary size
Rationale: Estuary size provides a broad surrogate for sensitivity to lateral flow inputs. Large
estuaries are typically fed by large catchments and lateral inputs can have localized effects. For
example run-off can decrease salinity encouraging reed encroachment. In small estuaries lateral
flow inputs would have a greater impact relative to overall size of the system. The size categories
from the National Biodiversity Assessment (NBA) document (Van Niekerk et al. 2012) have been
used (Large > 1000 ha, Medium 100-1000 ha, small 10-100 ha, very small <10 ha). About 50%
(144 estuaries) of South Africa’s estuaries are between 10 and 100 ha, while 32% (94 estuaries) are
less than 10 ha in size.
Method: NBA dataset available for estuary size. If necessary check the approximate area of the
estuary being assessed using available tools (e.g. GIS).
1.2 Estuary length
Rationale: Longer estuaries will be more sensitive to lateral inputs than shorter systems with a
smaller perimeter. Medium sized estuaries are between 10 and 20 km in length whereas small
systems are less than 5 km in length. Systems smaller than 500 m were not included in the national
estuary list of the NBA until such time as it can be established that they are of functional importance

Preliminary Guideline for the Determination of Buffer Zones 2014
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Method: NBA dataset available for estuary length. If necessary check the approximate length of the
estuary being assessed using available tools (e.g. GIS).
Perenniality of river inflows
Rationale: The perenniality of river inflow to an estuary affects how sensitive the estuary will be to
changes in water quantity and thus to impacts from adjoining land use. In this regard, estuaries fed
by non-perennial rivers are likely to be more affected by increases or decreases in water quantity
from lateral inputs than those fed by perennial inflow. The following classes are used to define
perenniality of rivers feeding the estuary being assessed; perennial, non-perennial (seasonal), and
non-perennial (intermittent).
Method: At a desktop level, perenniality may be interpreted from 1:50 000 topographical sheets
where rivers indicated with a solid line are considered to be perennial systems and dotted lines
represent non-perennial rivers (i.e. seasonal and intermittent). Distinction between seasonal and
intermittent rivers is made where the former consists of river systems that flow for extended periods
during the wet seasons/s (generally between 3 to 9 months), at intervals varying from less than a
year to several years (Ollis et al., 2013). Intermittent rivers flow for a relatively short time of less
than one season’s duration (i.e. less than approximately 3 months) at intervals varying from less
than a year to several years (Ollis et al., 2013).
Sensitivity to changes in patterns of flow (frequency, amplitude, direction of flow) from
lateral inputs?
Table 2. Estuary characteristics affecting the sensitivity of the water resource to changes in the
patterns of flow from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Inherent runoff potential of
catchment soils Low Mod. Low
Moderate Mod. high High
Mouth closure >80% 50-80%
50% 20-50% 20%
2.1 Estuary size
Rationale: Estuary size provides a broad surrogate for sensitivity to lateral flow inputs. In large
estuaries lateral inputs can have localized effects changing the frequency, amplitude and direction
of flow. For example run-off could add water to the system during a natural low flow period. This
would change salinity conditions and influence the biota at the specific sites of input. In small
estuaries lateral flow inputs would have a greater impact relative to the overall size of the system.
The size categories from the National Biodiversity Assessment (NBA) document (Van Niekerk et al.
2012) have been used (Large > 1000 ha, Medium 100-1000 ha, small 10-100 ha, very small <10
ha). About 50% (144 estuaries) of South Africa’s estuaries are between 10 and 100 ha, while 32%
(94 estuaries) are less than 10 ha in size.
Method: See method in 1.1 for assessing estuary size.

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2.2 Estuary length
Rationale: Longer estuaries will be more sensitive to changes in patterns of lateral inputs than
shorter systems with a smaller perimeter. Medium sized estuaries are between 10 and 20 km in
length whereas small systems are less than 5 km in length. Systems smaller than 500 m were not
included in the national estuary list of the NBA until such time as it can be established that they are
of functional importance
Method: See method in 1.2 for assessing estuary length.
2.3 Inherent runoff potential of catchment soils
Rationale: The ability of a catchment to partition runoff into surface and sub-surface flow
components depends largely on prevailing catchment conditions, which may be the result of both
natural and anthropogenic processes. Soils are a key natural regulator of catchment hydrological
response due the capacity that soils have for absorbing, retaining and releasing/redistributing water
(Schulze, 1989). Catchments dominated with deep, well-drained soils generally have high rates of
permeability and thus a greater proportion of rainfall can infiltrate into the soil profile. Consequently
catchments with highly permeable soils therefore have a much lower runoff potential compared to
soils with a low permeability (e.g. clay soils). As such, estuaries fed by catchments characterized by
higher permeabilities are characterized by less flashy flows than those fed by catchments
characterized by low permeabilities. Estuaries fed by catchment inputs which are naturally flashy
are therefore regarded as less sensitive to changes in the pattern of lateral water inputs (e.g.
increased runoff during heavy rains) than those characterised by less variable flow regimes.
Method: The Soil Conservation Services method for Southern Africa (SCS-SA) uses information of
hydrologic soil properties to estimate surface runoff from a catchment (Schulze et al., 1992). With
reference to the SCS-SA (Table 2), determine the appropriate hydrological soil group that defines
the entire catchment based on available soils information. Such information is obtainable from the
Land Type maps of South Africa, which includes information on soil texture.
2.4 Mouth closure as a measure of water exchange
Rationale: The duration of mouth closure can be used as a surrogate for tidal exchange. Those
estuaries closed to the sea are less influenced by tidal exchange. They will be more sensitive to
changes in the patterns of flow from lateral inputs. The duration of mouth closure is used to indicate
water retention. Open estuaries are usually characterized by higher freshwater inflow. Temporarily
open / closed estuaries will be more sensitive to lateral inputs than permanently open estuaries or
river mouths where these effects would be reduced by dilution from sea and river inputs.
Method: With the use of available data estimate the duration of mouth closure for a year.

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Sensitivity to changes in sediment inputs and turbidity from lateral inputs
Table 3: Estuary characteristics affecting the sensitivity of the water resource to increased sediment
inputs from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Water clarity Clear
blackwater turbid -
Submerged macrophytes
present (adjacent
planned development) Yes
No
3.1 Estuary size
Rationale: Estuary size provides a broad surrogate for sensitivity to sediment inputs. Large
estuaries have a greater inherent buffer capacity and are therefore less likely to be affected by
changes in lateral sediment inputs than small estuaries where moderate changes in sediment inputs
could have a substantial impact by reducing water depth and affecting hydrodynamic functions. The
size categories from the National Biodiversity Assessment (NBA) document (Van Niekerk et al.
2012) have been used (Large > 1000 ha, Medium 100-1000 ha, small 10-100 ha, very small <10
ha). About 50% (144 estuaries) of South Africa’s estuaries are between 10 and 100 ha, while 32%
(94 estuaries) are less than 10 ha in size.
Method: See method in 1.1 for assessing estuary size.
3.2 Estuary length
Rationale: Longer estuaries will be more sensitive to lateral inputs than shorter systems with a
smaller perimeter. Medium sized estuaries are between 10 and 20 km in length whereas small
systems are less than 5 km in length. Systems smaller than 500 m were not included in the national
estuary list of the NBA until such time as it can be established that they are of functional importance.
Method: See method in 1.2 for assessing estuary length.
3.3 Water clarity
Rationale: Clear estuaries will be more sensitive to lateral inputs than naturally turbid systems.
Blackwater systems are those which are rich in tannins. The National Biodiversity Assessment has
classified all estuaries as “clear, blackwater or turbid” based on the quality of the freshwater inflow
to the system.
Method: NBA dataset available for river water inflow types as an indication of estuary water clarity.
3.4 Presence of submerged macrophytes
Rationale: Submerged macrophytes are sensitive to changes in the light environment caused by
sediment input and changes in turbidity. The distribution of submerged macrophytes is limited in
South African estuaries due to a variety of pressures and therefore they are sensitive to further
disturbances. Dominant species in South African estuaries are Zostera capensis which grows in the

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intertidal zone and Ruppia cirrhosa and Potamogeton pectinatus that grow in closed estuaries or in
the upper more freshwater rich areas of estuaries.
Method: The NBA database indicates those estuaries where submerged macrophtyes are present.
The estuary habitat adjacent to the planned development should be checked in the field for the
presence of submerged macrophytes. Reports and aerial photographs should also be used to
assess whether submerged macrophytes have occurred in the area. This is necessary as these
plants are dynamic and rapidly change their habitat distribution in response to droughts and floods.
Sensitivity to increased inputs of nutrients (phosphates, nitrite, nitrate) from lateral inputs
Table 4: Estuary characteristics affecting the sensitivity of the water resource to increase nutrient
inputs from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Water clarity Clear
blackwater turbid -
Mouth closure >80% 50-80%
50% 20-50% <20%
Submerged macrophytes
present (adjacent planned
development) Yes
No
4.1 Estuary size
Rationale: Estuary size provides a surrogate for sensitivity to nutrient inputs. Large estuaries have
a greater inherent buffering capacity and are therefore less likely to be affected by changes in lateral
nutrient inputs than small estuaries where moderate changes in nutrient inputs could have an
impact on natural nutrient dynamics. The size categories from the NBA document (Van Niekerk et
al. 2012) have been used (Large > 1000 ha, Medium 100 – 1000 ha, small 10-100 ha, very small
<10 ha).
Method: See method in 1.1 for assessing estuary size.
4.2 Estuary length
Rationale: Longer estuaries will be more sensitive to lateral inputs than shorter systems with a
smaller perimeter. Medium sized estuaries are between 10 and 20 km in length whereas small
systems are less than 5 km in length. Systems smaller than 500 m were not included in the national
estuary list of the NBA until such time as it can be established that they are of functional importance
Method: See method in 1.2 for assessing estuary length.
4.3 Water clarity
Rationale: Typically clear estuaries will therefore be more sensitive to lateral inputs than naturally
turbid systems. Blackwater systems are those which are rich in tannins.
Method: NBA dataset available for river water inflow types as an indication of estuary water clarity.
4.4 Mouth closure as a measure of flushing / residence time

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Rationale: Flushing time is the time required to replace the existing water in the estuary at a rate
equal to river inflow. Reduced flushing will result in greater accumulation of nutrients. An ongoing
study on the desktop assessment of estuary water quality is developing a flushing rate index for all
South African estuaries (Taljaard pers comm.). This measure is based on the estuary volume
relative to the daily inflow volume and the percentage of time that the mouth of the estuary is open
in a year. In the absence of these data the duration of mouth closure can be used to indicate
retention of nutrients. Temporarily open / closed estuaries will be more sensitive to nutrient inputs
than permanently open estuaries or river mouths where these effects would be reduced by dilution
from sea and river inputs.
Method: With the use of available data estimate the duration of mouth closure for a year.
4.5 Presence of submerged macrophytes
Rationale: Submerged macrophytes are outcompeted by the faster growing macroalgae, particularly
filmanentous greens under nutrient rich conditions. The distribution of submerged macrophytes is
limited in South African estuaries due to a variety of pressures and therefore they are sensitive to
further disturbances such as nutrient inputs.
Method: The NBA database indicates those estuaries where submerged macrophtyes are present.
Where feasible, this should be checked in the field as this is a dynamic habitat changing in response
to droughts and floods.
Sensitivity to increases in toxic contaminants (including toxic metal ions (e.g. copper, lead,
zinc), toxic organic substances (reduces oxygen), hydrocarbons and pesticides) from lateral
inputs
Table 5. Estuary characteristics affecting the sensitivity of the water resource to changes in
contaminants from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Mouth closure >80% 50-80%
50% 20-50% <20%
5.1 Estuary size
Rationale: See Rationale 4.1 Method: See method in 1.1 for assessing estuary size.
5.2 Estuary length
Rationale: See Rationale 4.2.
Method: See method in 1.2 for assessing estuary length.
5.3 Mouth closure
Rationale: See Rationale 4.4.
Method: See method in 4.4 for assessing frequency of mouth closure.
Sensitivity to changes in acidity (pH) from lateral inputs.

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Table 6 Estuary characteristics affecting the sensitivity of the water resource to changes in acidity
(pH) from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Mouth closure >80% 50-80%
50% 20-50% <20%
6.1 Estuary size
Rationale: See Rationale 4.1
Method: See method in 1.1 for assessing estuary size.
6.2 Estuary length
Rationale: See Rationale 4.2.
Method: See method in 1.2 for assessing estuary length.
6.3 Mouth closure
Rationale: See Rationale 4.4.
Method: See method in 4.4 for assessing frequency of mouth closure.
Sensitivity to changes in salinity from lateral inputs
Table 7. Estuary characteristics affecting the sensitivity of the water resource to changes in salinity
from lateral inputs
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha
10-50 ha 50-100 ha >100 ha
Estuary length <5 km
5-10 km 10-20 km >20 km
Mouth closure >80% 50-80%
50% 20-50% <20%
Inputs from lateral flow can have a localized effect in estuaries. For example development and run-
off often freshens the system leading to a loss of salt marsh and expansion of reeds at the estuary
boundary. Similarly run-off from some sources such as salt works / salt pans can increase salinity
causing die-back of estuarine vegetation such as reeds, sedges and salt marsh. All natural plant
communities in estuaries would have a high sensitivity to salinity changes caused by lateral flow
inputs.
Naturally saline estuaries (which are more open to sea), are characterized by highly variable salinity
and likely to be less sensitive than estuaries that are naturally characterized by lower and less
variable salinity levels. Estuaries in the warm-temperate zone are characterized by low rainfall and
runoff which results in elevated salinity (Harrison 2004) and sensitivity to lateral inflows.
7.1 Estuary size

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Rationale: See Rationale 4.1
Method: See method in 1.1 for assessing estuary size.
7.2 Estuary length
Rationale: See Rationale 4.2.
Method: See method in 1.2 for assessing estuary length.
7.3 Mouth closure
Rationale: See Rationale 4.4.
Method: See method in 4.4 for assessing frequency of mouth closure.
Sensitivity to changes in water temperature from lateral inputs
Table 8. Estuary characteristics affecting the sensitivity of the water resource to changes water
temperature from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Estuary size <10 ha 10-50 ha 50-100 ha >100 ha
Estuary length <5 km 5-10 km 10-20 km >20 km
Biogeographic zone Low
latitude
Subtropical
Moderate
latitude
Warm
temperate
High
latitude
Cool
temperate
Inputs from lateral flow could have a localized temperature effect in estuaries. Industries can
discharge warm or cool waters. Temperature in estuaries follow the trend for marine coastal waters,
decreasing from the subtropical east coast, along the warm-temperate south coast and up the cool-
temperate west coast. Naturally cooler systems are likely to be more susceptible to increased water
temperatures from lateral inputs than are warmer estuaries.
8.1 Estuary size
Rationale: See Rationale 4.1
Method: See method in 1.1 for assessing estuary size.
8.2 Estuary length
Rationale: See Rationale 4.2.
Method: See method in 1.2 for assessing estuary length.

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8.3 Biogeographic zone
Rationale: Estuaries characterized by cooler water are more sensitive to thermal pollution than
those with higher temperatures. Estuaries situated on the west coast are generally cooler and thus
more sensitive to increases in water temperature.
Method: Determine the biogeographic zone in-which the estuary is located using the map provided
in Figure 1, below. This shows that all estuaries north of the Mbashe Estuary are subtropical, while
those west of Heuningnes Estuary are cool temperate. Estuaries located in between are classified
as warm temperate estuaries.
Figure 1. Map of Biogeographic Zones as used in National Spatial Biodiversity Assessment (NSBA
2004) for Estuarine Ecosystems (from Harrison 2003)
Sensitivity to changes in pathogens from lateral inputs
Table 10: Estuary characteristics affecting the sensitivity of the estuary to increased pathogen
inputs from lateral sources
CRITERION SENSITIVITY SCORES
1.15 1.075 1 0.925 0.85
Overall size <10 ha
10-50 ha 50-100 ha >100 ha
Length <5 km
5-10 km 10-20 km >20 km
Level of domestic use High Moderate Low

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9.1 Estuary size
Rationale: Estuary size provides a surrogate for sensitivity to lateral inputs. Large estuaries have a
greater inherent buffer capacity and are therefore less likely to be affected by increases in pathogen
inputs than small estuaries where moderate increases in pathogen inputs could lead to rapid
increases in pathogen levels.
Method: See method in 1.1 for assessing estuary size.
9.2 Estuary length
Rationale: Longer estuaries will be more sensitive to lateral inputs than shorter systems with a
smaller perimeter. Medium sized estuaries are between 10 and 20 km in length whereas small
systems are less than 5 km in length. Systems smaller than 500 m were not included in the national
estuary list of the NBA until such time as it can be established that they are of functional importance
Method: See method in 1.2 for assessing estuary length.
9.3 Level of domestic use
Rationale: The higher the level of domestic water use, the higher the threat of increasing pathogen
levels to water users.
Method: Based on an evaluation of land use around the estuary and discussions with local
stakeholders, establish the level of domestic water use (including recreational use).
References
Harrison, T.D., 2003. Biogeography and community structure of fishes in South African estuaries.
PhD Thesis, Rhodes University, Grahamstown, South Africa.
Harrison T.D., 2004. Physico-chemical characteristics of South African estuaries in relation to the
zoogeography of the region. Estuarine, Coastal and Shelf Science 61: 73-87.
Ollis, D., Snaddon, K., Job, N., Mbona, N., 2013. Classification system for wetlands and other
aquatic ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22.
South African National Biodiversity Institute, Pretoria.
Schulze, R.E., (ed) 1989. ACRU: Background concepts and theory. ACRU Report No. 36,
Department of Agricultural Engineering, University of Natal, Pietermaritzburg, RSA.
Schulze, R.E., Schmidt, E.J., Smithers, J.C., 1992. PC-based SCS flood estimates for small
catchments in Southern Africa. Department of Agricultural Engineering, University of Natal,
Pietermaritzburg, RSA.
van Niekerk, L., Adams, J.B., Bate, G., Cyrus, D., Demetriades, N., Forbes, A., Huizinga, P.,
Lamberth, S.J., MacKay, F., Petersen, C., Taljaard, S., Weerts, S., Whitfield A.K., Wooldridge, T.H.,
2012. Health status of estuaries. In: Van Niekerk, L., Turpie, J.K., (eds) 2012. South African
National Biodiversity Assessment 2011: Technical Report. Volume 3: Estuary Component. CSIR
Report Number SIR/NRE/ECOS/ER/2011/0045/B. Council for Scientific and Industrial Research,
Stellenbosch.

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Annexure 15 – Development of rule-curves to link buffer efficiency to
buffer width
This annexure includes a summary of the available scientific literature used to inform the
development of rule-curves that link buffer efficiency to buffer width for selected buffer functions.
These rule curves form the basis for buffer zone determination in the buffer zone models but are
refined to cater for climatic variability, the sensitivity of the receiving environment and buffer zone
attributes for the site-based assessment.
1. Increased sedimentation and turbidity
Yuan, Bingner & Locke (2009) recently undertook a thorough review of the effectiveness of
vegetative buffers on sediment trapping in agricultural areas. In this review of a large number of
quantitative studies, there was clear evidence that although sediment trapping capacities are site-
and vegetation-specific, and many factors influence the sediment trapping efficiency, the width of a
buffer is important in filtering agricultural runoff and wider buffers tended to trap more sediment.
Despite some variability between studies, results indicated that first 3-6 m of a buffer plays a
dominant role in sediment removal. This finding is backed up by Sheldon et al. (2003) who showed
that the relationship between the length covered by the runoff (buffer width) and sediment removal
is not linear, with most sediment being deposited in outer portions of the buffer. In a study
undertaken by Barling and Moore (1994) for example on forested buffers, the majority (91%) of
sediment deposition took place within the first 0.25 to 0.6 m of the outer edge of the buffer.
Robinson et al. (1996) also found that sediment was reduced by 70% and 80% from the 7% and
12% slope plots, respectively, within the first 3 m of the buffer. Dillaha et al. (1989) and Magette et
al. (1989) reported sediment trapping efficiencies of 70-80% for 4.6 m and 84-91% for 9.1 m wide
grass filter strips. Yuan, Bingner & Locke (2009) conclude that generally, buffers 4-6 m can reduce
sediment loading by more than 50%.
Yuan, Bingner & Locke (2009) further report that buffers greater than 6 m are effective and reliable
in removing sediment from any situation. They refer; for example to Hook et al. (2003), who
reported that more than 97% of sediment was trapped in the rangeland riparian buffer area with a 6
m buffer in any of the experimental conditions they studied. Sheridan et al. (1999) reported
sediment trapping efficiencies of 77-90% across three different management schemes (clear cut,
thinned, and untouched) when studying the impact of forest management practices within the
riparian zone. Cooper et al. (1992) estimated that 90% of the sediment leaving fields was retained in
the wooded riparian zone.
Yuan, Bingner & Locke (2009) indicated that the overall, the sediment trapping efficiency to buffer
width relationship can be best fitted with logarithm models (Figure 1). This is similar to the
relationship previously developed by Gilliam (1994) and to that recently modelled by Zhang et al.
(2009).

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159
Figure 1. Buffer width and sediment trapping efficiency (Yuan, Bingner & Locke (2009)).
According to this relationship, a 5 m buffer can trap about 80% of incoming sediment. Yuan, Bingner
& Locke (2009) further observed that effectiveness differed among buffer width categories
(Figure 2). Buffers of 3-6 m wide have greater sediment trapping efficiency than buffers of 0-3 m
wide, and buffers of greater than 6 m wide have greater sediment trapping efficiency than buffers of
3-6 m wide. Thus, wider buffers are likely to be more efficient in trapping sediment than narrower
buffers.
Figure 2. Average, minimum, and maximum sediment trapping efficiency for different buffer width
category. Yuan, Bingner & Locke (2009)).
Based on this information, a curvilinear relationship between sediment removal efficiency and buffer
width is assumed. Details of starting buffer widths proposed on the basis of risk and associated
buffer effectiveness scores are provided below.

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RISK
CLASS EFFECTIVEN
ESS (%) BUFFER
WIDTH
Very Low 25 2
Low 50 5
Moderate 80 15
High 90 30
Very High 95 50
It is important to note however that these results reflect buffer effectiveness in situations where the
buffer is designed to trap sediment (good vegetative cover) and concentrated flows are avoided.
High levels of variability are also known to be reported for different size particles, with fine particles
requiring a far larger buffer width.
2. Increased nutrient inputs from lateral inputs
Many studies have shown >90% reductions in nitrate concentrations in subsurface flows as water
passes through riparian areas or wetlands (e.g. Gilliam 1994, Fennesey & Cronk 1997). Buffers are
consistently reported to reduce nitrate to below 2 mg/L (in line with SLV limits), often throughout the
year and even when nitrate inputs are extremely high (Muscutt et al. 1993). As such, the
establishment of buffer zones is regarded as an effective and appropriate mitigation measure to
remove nitrogen from diffuse lateral inputs.
In a recent meta-analysis of 73 studies undertaken by Zhang et al. (2009), theoretical models were
developed to quantify the relationship between pollutant removal efficiency and buffer width.
Models developed, suggested that buffer width was a primary factor affecting nutrient removal
efficiency, with about 50% of the variation in N removal efficiency and 48% of the variation in P
removal efficiency explained by buffer width and vegetation. This highlights the usefulness of buffer
width as a primary discriminator for assessing nutrient removal efficiency.
Another recent meta-analysis of Nitrogen Removal in Riparian Buffers was undertaken by Mayer et
al. (2007). This included analysis of data from 89 individual riparian buffers from 45 published
studies. Although nitrogen removal effectiveness varied widely among studies, there was a clear
relationship between buffer width and buffer effectiveness. In particular, this review showed that
Nitrogen removal effectiveness of buffers 50 m wide was greater than that of buffers 0 to 25 m,
whereas effectiveness of buffers 26 to 50 m did not differ from the other categories (Figure 3).
Thus, wider buffers are likely to be more efficient zones of nitrogen removal than narrower buffers.
0
20
40
60
80
100
0 20406080100
Removal efficiency (%)
Buffer Requirement

Preliminary Guideline for the Determination of Buffer Zones 2014
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Figure 3. Nitrogen removal effectiveness in riparian buffers by buffer width category. Bars represent
means ±standard error. Mean ranks of width categories differ if denoted by different letters (Kruskal-
Wallis one-way analysis of variance on ranks with Dunn’s method of multiple comparisons, P, 0.05).
Based on a limited data set fitted to a log-linear model, Oberts and Plevan (2001) found that NO3-
retention in wetland buffers was positively related to buffer width (R2 values ranged from 0.35-0.45).
Nitrogen removal efficiencies of 65 to 75% and 80 to 90% were predicted for wetland buffers 15 and
30 m wide, respectively, depending on whether NO3- was measured in surface or subsurface flow
(Oberts and Plevan, 2001). A similar relationship was demonstrated by Mayer et al. (2007) but with
their model suggesting that removal efficiencies of 50, 75, and 90% occurred at buffer widths of 4,
49, and 149 m respectively as illustrated in Figure 4, below.
Figure 4. Relationships of nitrogen removal effectiveness to riparian buffer width over all studies
and analysed by water flowpath (Mayer et al., 2007).

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Zhang et al. (2009) also developed a curvilinear relationship for illustrating the relationship between
buffer efficiency and nutrient removal efficiency. These relationships are presented in Figure 5,
below and suggest that higher levels of buffer efficiency can be achieved with small buffers less
than 25 m in width.
Figure 5. Pollution removal efficiency vs. buffer width for nitrogen and phosphorous. Dotted lines
indicate 95% confidence band (Zhang et al., 2009).
Based on this information, a curvi-linear relationship between nutrient removal efficiency and buffer
width is assumed, with the following conservative starting buffer widths proposed on the basis of risk
and associated buffer effectiveness scores.
RISK
CLASS EFFECTIVENESS
(%) BUFFER
WIDTH
Very Low 25 2
Low 50 5
Moderate 80 25
High 90 50
Very High 95 100
3. Increased toxic contaminants from lateral inputs
When developing guidelines for the width of buffer zones to address threats posed by toxic
contaminants, it is first important to note that the term “toxic contaminants” covers a broad suite of
potentially toxic substances. These include toxicants (including toxic metal ions (e.g. copper, lead,
zinc, etc.), toxic organic substances (which reduce oxygen availability), hydrocarbons, and
pesticides. In addition, the efficiency of a buffer at trapping toxic substances is dependent on a wide
range of factors, such as residence times, flushing rates, and dilution and re-suspension rates of the
toxic substances.
0
20
40
60
80
100
0 20406080100
ERemoval efficiency (%)
Buffer req uirement

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Buffer guidelines could potentially be tailored according to specific toxic substances. However, this
is unrealistic for this project and little information is also available on buffer zone efficiencies for all
toxic substances. As an initial approach to determining the effectiveness of a buffer zone at trapping
toxic substances, toxic contaminants have been considered as two broad categories, namely
organic contaminants (which include pesticides) and toxic heavy metals. Buffer widths proposed for
these groups have been based on available information. In addition, the precautionary principle was
also applied.
A review of international literature does provide some useful indicators of the efficiencies of buffers
of particular widths for removing certain toxic contaminants. According to Blanche (2002) removal
efficiencies for sediment-attached and dissolved toxics are likely to be similar to those determined
for sediments and dissolved nutrients. However, literature also highlights the differences with
respect to organic pollutants and pesticides, and metals. These broad categories are discussed in
the following subsections.
3.1 Organic pollutants and pesticides
Organic pollutants include substances such as persistent organic pollutants (POPs, e.g. DDT and its
metabolites), various organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs),
dioxin-like compounds (DLCs), and non-dioxin-like polychlorinated biphenyls (PCBs). Most organic
toxicants are hydrophobic and do not dissolve readily in water and general bind to organic matter in
sediments. Some can stay in the sediment for long periods of time with minimal breakdown and
natural decomposition while others break down relatively quickly under anaerobic conditions.
Substance breakdown is dependent on environmental factors, which need to be considered when
interpreting decomposition data for the different organic toxicants (Gevao et al., 2010).
Bioaugmentation of the sediment and sorption by plants and organic matter is of particular
importance in the removal of some organic pollutants from the environment. There is a general lack
of knowledge on the detailed removal pathways for organic compounds (Haberl et al., 2003), which
renders determining the effectiveness of buffers a challenge. Given the vast range of organic toxic
substances and the limited literature concerning buffer removal efficiencies, pesticides have been
selected as a sub-group representative of organic toxic substances.
Individual pesticide characteristics have a significant bearing on removal efficiency as this affects
the mechanism of removal, which can be either by co-deposition with sediment or by immobilization
from solution. This is determined primarily by the adsorbing properties of the pesticide, which
determines its ability to adsorb to organic carbon in sediment. Where pesticides have a strong
adsorption capacity most of the pesticide is lost as co-deposition with sediment (Reichenberger
et al., 2007). Removal efficiencies for these pesticides are therefore likely to be similar to those for
sediment retention (Zhang et al., 2009). Zhang et al. (2009) developed a model for pesticide
removal efficiency based on a review of 49 studies. Buffer width alone accounted for over half the
variation in pesticide removal efficiency in these studies, supporting the notion that buffer width is a
primary driver of pesticide removal. This model suggested that a 30 m buffer could remove 93% of
pesticides in runoff. This relationship is illustrated in Figure 6, below. These results are comparable
to the results presented Reichenberger et al. (2007), in a review of 14 studies who indicated that on
average, pesticide load reduction efficiencies were 50% reduction for 5 m buffers strips, 90% for
10 m buffer width and 97.5% for 20 m widths. Variability in efficiencies were however very high,
particularly for pesticides predominantly transported in the water phase (low adsorption capacity).

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This resulted in more conservative assumptions being applied to the full spectrum of pesticides and
organic pollutants.
Figure 6. Removal efficiency vs. buffer width for pesticides. Dotted lines indicate 95% confidence
band (Zhang et al., 2009).
Based on this information, a curvilinear relationship between organic pollutant / pesticide removal
efficiency and buffer width is assumed, with the following starting buffer widths proposed on the
basis of risk and associated buffer effectiveness scores.
RISK
CLASS EFFECTIVENESS
(%) BUFFER
WIDTH
Very Low 25 2
Low 50 5
Moderate 80 10
High 90 20
Very High 95 40
3.2 Heavy / Toxic metals
Limited information is available on the mobilisation of toxic metals by overland flow through buffers.
Generally, metals are transported through the landscape attached to particles in sediments or
dissolved in storm water. The concentration of the metal will depend mainly on the concentration of
the metal at the source and the source substance’s solubility.
In a dissolved state, the biological availability and chemical reactivity (sorption or desorption,
precipitation or dissolution) towards other components is determined by the chemical form of the
metal (Pintilie et al. 2003). Charged species are retained by sorption processes and the removal
efficiencies are governed by the predominant ionic species and complexes (Hamilton & Harrison,
1991). Preliminary findings do however suggest that this varies considerably for the different heavy
metals considered. Dissolved species of Zn, Cd, Pb, and Cr are more effectively removed than Cu
and Fe (Yousef et al., 1987).
0
20
40
60
80
100
0 20406080100
Removal efficiency (%)
Buffer Requirement

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Yousef et al. (1987) also found swales36 to filter out heavy metals through adsorption, precipitation
and/or biological uptake. Average mass removal rates were however highly site and condition
specific and influenced by the total mass input (concentrations), velocity of flow and percentage of
infiltration. Table 1, below, presents the pollutant removal efficiencies for swale lengths of 61 meters
and 30 meters reported in a report prepared for the U.S. Environmental Protection Agency.
Although research results varied between studies, these data clearly indicate greater pollutant
removal for wider swales. Indeed, this data suggest that removal efficiencies of 30 m wide swales
are limited but increase to 50-70% at widths close to 60 m.
Table 1. Swale Pollutant Removal Efficiencies (Barret et al., 1993; Schueler, et.al., 1991, Yu, 1993
and Yousef et al., 1985) as reported in Clar et. al., 2004.
Given the lack of available data for various heavy metals, comparative studies are also useful when
comparing buffer zone effectiveness relationships with that of other pollutants. In this regard, the
study alluded to above suggests that sediment removal efficiency of buffer zones is likely to be
higher than for metals but that nutrient removal effectiveness is lower (Table 1). Hamilton &
Harrison (1991) also noted that metals are more effectively removed than Nitrogen and Phosphorus.
This finding is also supported through a reported study by the U.S. Department of Transportation
who conducted a field study to determine the pollutant removal efficiencies of grassed channels and
swales along highways in the U.S.A. (U.S. Environmental Protection Agency, 2000). This research
showed that removal of metals was found to be directly related to the removal rate of total
suspended solids, and the removal rate of metals was greater than removal of nutrients.
A range of other studies have also suggested strong linkages between removal of metal and
sediment removal (e.g. Yousef et al., 1985; U.S. Environmental Protection Agency, 2000; Caltrans,
2003; Barrett et al., 2004). These findings therefore suggest that buffer requirements for metal
removal should be strongly linked to that of sediment removal but that wider buffers should be
advocated for nutrient removal.
Various authors do however emphasize that chemical removal ability is finite: once metals are
adsorbed to soils, they can be freed for transport by further chemical or physical disturbance of the
soil layer (e.g. Kearfott et al., 2005). The capacity of soils to retain heavy metals over the long-term
is another important consideration, and would probably require regular monitoring to ensure that
assimilative capacities of the soils were not exceeded. As such, the application of somewhat
36 According to Deeks & Milne (2005), vegetated swales and buffers perform both a stormwater treatment and
stormwater conveyance function. Both systems treat stormwater via filtration through the vegetation. Additional
pollutant removal is achieved through stormwater infiltration to groundwater and vegetative uptake.

Preliminary Guideline for the Determination of Buffer Zones 2014
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conservative buffer widths is recommended in high risk scenarios where heavy contaminant loads
could reduce buffer zone efficiencies over time.
Based on this information, a curvilinear relationship between metal removal efficiency and buffer
width is assumed. Following a precautionary approach the following starting buffer widths have
been proposed for different risk classes.
RISK
CLASS EFFECTIVENESS
(%) BUFFER
WIDTH
Very Low 25 2
Low 50 5
Moderate 80 22.5
High 90 45
Very High 95 80
It is important to note that chemical removal ability is finite. Once metals are adsorbed to soils, they
can be freed for transport by further chemical or physical disturbance of the soil layer. The capacity
of soils to retain heavy metals over the long-term is another important consideration, and would
probably require regular monitoring to ensure that assimilative capacities of the soils were not
exceeded. The effectiveness of the buffer zone will also depend on the metal in question.
4. Increased pathogen inputs from lateral sources
Most pathogenic bacteria are removed by physical and chemical adsorption within the soil profile
(Gerba and others 1975), and faecal coliform bacteria (FCB) concentrations therefore typically
decline substantially when transported through soil, suggesting that transport to surface water
occurs mainly by surface flow (Abu-Ashour and others 1994; Howell and others 1996; Huysman and
Verstraete 1993; Kunkle 1970). Buffer zones that are able to intercept surface flow, promote
leaching and prevent or retard overland transport may therefore be effective in reducing pathogen
loads entering water resources (Sullivan et al., 2007).
Studies undertaken on the effectiveness of buffers in removing FCB suggest that small buffers may
be effective in performing this function. Indeed, in a study by Sullivan et al. (2007), showed that the
presence of a vegetated buffer of any size, from 1 to 25 m, generally reduced the median FCB
concentration of runoff water after heavy storms from agricultural land amended with dairy cow
manure by more than 99%. Only 10% of the runoff samples collected from treatment cells having
vegetated buffers exhibited FCB concentrations >200 faecal coliforms / 100 ml, and the median
concentration for all cells containing vegetated buffers was only 6 faecal coliforms / 100 ml. This
suggests that very narrow vegetated buffer strips can effectively reduce FCB levels to within GLV
limits of 1000 faecal coliforms / 100 ml.
0
20
40
60
80
100
0 20406080100
Removal efficiency (%)
Buffer Requirement

Preliminary Guideline for the Determination of Buffer Zones 2014
167
Results obtained by Roodsari and others (2005) provide additional evidence that small buffers can
be very effective at absorbing FCBs. This showed that FCB released from surface-applied bovine
manure through a 6 m buffer strip with a 20% slope was reduced to 1% of the applied bacteria
amount on the vegetated clay loam soil and nondetectable on the vegetated sandy loam soil. These
findings do however conflict with findings from earlier studies which suggested that wider buffer
zones were required to effectively reduce FCB levels. For example, a faecal reduction model
developed by Grismer (1981), suggested that 30 m buffers would only reduce FCB levels by 60%.
Young and others (1980), similarly concluded that 35 m vegetated buffers were required to reduce
FCB levels from feedlot runoff during summer storms. Sullivan et al. (2007) do point out however
that these earlier studies employed experimental designs based on high rates of artificial irrigation to
force soil saturation and overland flow. They therefore conclude that new regulations that specify
uniform minimum buffer sizes of 10.8 m (cf. US EPA 2003) may be unnecessary for water quality
protection under some soil and slope conditions.
Based on the information available, maximum starting buffers for FCB removal were set at 30 m,
reduced to 2 m in the case of low-risk activities. Given that research suggests that very small
buffers are effective at removing pathogens, a curvi-linear relationship was again assumed as
illustrated below.
RISK
CLASS EFFECTIVENESS
(%) BUFFER
WIDTH
Very Low 25 2
Low 50 4
Moderate 80 10
High 90 20
Very High 95 30
5. References
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through soil. Water, Air and Soil Pollution 75: 141-158.
Barling, R. D., Moore, I.D., 1994. Role of buffer strips in management of waterway pollution: A
review. Environmental Management 18: 543-558.
Barret, M.E., Zuber, R.D., Collins III, E.R., Malina Jr., J.F., Charbeneau, R.J., Ward, G.H., 1993. A
review and evaluation of literature pertaining to the quantity and control of pollution from highway
runoff and construction. Centre for Research in Water Resources, Bureau of Engineering and
Research, The University of Texas, Austin, USA. First Edition.
Barrett, M., Lantin, A., Austrheim-Smith, S. 2007. Stormwater pollutant removal in roadside
vegetated buffer strips. Cited in: CTC and Associates LLC., 2007. Grass Swales: gauging their
0
20
40
60
80
100
0 20406080100
ERemoval efficiency (%)
Buffer requirement

Preliminary Guideline for the Determination of Buffer Zones 2014
168
ability to remove pollutants from highway stormwater runoff. Prepared for Bureau of Equity and
Environmental Services, Division of Transportation System Development.
Blanché, C., 2002. The Use of riparian buffer zones for the attenuation of Nitrate in agricultural
landscapes. MSc Thesis, University of Natal, Pietermaritzburg, South Africa.
Caltrans Stormwater Quality Handbook, 2003. California Department of Transportation, Division of
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Clar, M.L., Barfield, B.J., O’Connor, T.P., 2004. Stormwater best management design practice
design guide Volume 1: General considerations. United States Environmental Protection Agency,
Cincinnati, Ohio, USA.
Cooper, A.B., Smith, C.M., Bottcher, A.B., 1992. Predicting runoff of water, sediments and nutrients
from a New Zealand grazed pasture using CREAMS. Transactions of the American Society of
Agricultural Engineers 35: 105-112.
Deeks, B., Milne, T., 2005. Water Sensitive Urban Design Site Development Guidelines and Notes.
Engineering Procedures for Stormwater Management in Southern Tasmania. Derwent Estuary
Program, Department of Primary Industries Water and Environment, Hobart, Tasmania.
Dillaha, T.A., Reneau, R.B., Lee, D., 1989. Vegetative filter strips for agricultural nonpoint pollution
control. Transactions of the American Society of Agricultural Engineers 32: 513-519.
Fennessy, M.S., Cronk, J.K., 1997. The effectiveness and restoration potential of riparian ecotones
for the management of nonpoint source pollution, particularly nitrate. Critical Reviews in
Environmental Science and Technology 27: 285-317.
Gerba, C.P., Wallis, C., Melnich, J.L., 1975. Fate of wastewater bacteria viruses in the soil. Journal
of Irrigation and Drainage Engineering 101: 157-174.
Gevao, B., Alegria, H., Jaward, F., Beg, M., 2010, Persistent organic pollutants in developing world.
In: Harrad, S., (ed) 2010. Persistent organic pollutants. Wiley, Blackwell Publishing, pp. 137-169.
Gilliam, J. W., 1994. Riparian wetlands and water quality. Journal of Environmental Quality 23: 896-
900.
Grismer, M.E., 1981. Evaluating dairy waste management systems influence on fecal coliform
concentration in runoff. MSc Thesis, Oregon State University, Oregon.
Haberl, R., Grego, S., Langergraber, G., Kadlec, R.H., Cicalini, A-R., Dias, S.M., Novais, J.M.,
Gerth, A., Thomas, H., Hebner, A., 2003. Constructed wetlands for the treatment of organic
pollutants. Journal of Soils and Sediments 3: 109-124.
Hamilton, R.S., Harrison, R.M., (Eds), 1991. Studies in Environmental Science 44: Highway
Pollution. Elsevier Science Publishing Company Inc., New York, USA.

Preliminary Guideline for the Determination of Buffer Zones 2014
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Hook. P.B., 2003. Sediment retention in rangeland riparian buffers. Journal of environmental
quality 32: 1130-1137.
Howell, J.M., Coyne, M.S., Cornelius, P.L., 1996. Effect of sediment particle size and temperature
on fecal bacteria mortality rates and the fecal coliform/fecal streprococci ratio. Journal of
Environmental Quality 25: 1216-1220.
Huysman, F., Verstraete, W., 1993. Water-facilitated transport of bacteria in unsaturated soil
columns: influence of cell surface hydrophobicity and soil properties. Soil Biology and Biochemistry
25: 83-90.
Kearfott, P.J., Barrett, M.E., Malina, J.F., 2005. IDS-Water – White Paper. Center for Research in
Water Resources, University of Texas, Texas, USA.
Kunkle, S.H., 1970. Concentrations and cycles of bacterial indicators in farm surface runoff. Cornell
University, Ithaca, New York. Relationship of Agriculture to Soil and Water.
Magette, W.L., Brinsfield, R.B., Palmer, R.E., Wood, J.D., 1989. Nutrient and sediment removal by
vegetated filter strips. Transactions of the American Society of Agricultural Engineers 32: 663-667.
Mayer, P.M., Reynolds, S.K., McCutchen, M.D., Canfield, T.J., 2007. Meta-analysis of nitrogen
removal in riparian buffers. Journal of Environmental Quality 36: 1172-1180.
Muscutt, A.D., Harris, D.L., Bailey, S.W., Davies, D.B., 1993. Buffer zones to improve water quality:
a review of their potential use in the UK agriculture. Agricultural Ecosystems and Environment 45:
59-77.
Oberts, G., Plevan, A., 2001. Benefits of wetland buffers: a study of functions, values and size.
Technical Report. Emmons and Oliver Resources Inc., Oakdale, Minnesota.
Pintilie, S., Brânză, L., Beţianu, C., Pavel, L. V., Ungureanu, F., Gavrilescu, M., 2007. Modelling and
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Management Journal 6:153-161.
Pontollilo, J., Eganhouse, R., 2001. The search for reliable aqueous solubility (Sw) and octanol-
water coefficient (Kow) data for hydrophobic organic compounds—DDT and DDE as a case study:
U.S. Geological Survey Water-Resources Investigation Report 01/42/01, pp. 51.
Prokop Z., Vangheluwe M.L., Van Sprang P.A., Janssen C.R., Holoubek I., 2003. Mobility and
toxicity of metals in sandy sediments deposited on land. Ecotoxicology and Environmental Safety
54: 65-73.
Reichenberger, S., Bach, M. Skitschak, A., Frede, H-G., 2007. Mitigation strategies to reduce
pesticide inputs into ground and surface water and their effectiveness: A review. Science of the
Total Environment 384: 1-35.

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Robinson, C.A., Ghaffarzader, M., Cruse, R.M., 1996. Vegetation filter strips effects on sediment
concentration in cropland runoff. Journal of Soil and Water Conservation 51: 227-230.
Roodsari, R.M., Shelton, D.R., Shirmohammadi, A., Pachepsky, Y.A., Sadeghi, A.M., Starr, J.L.,
2005. Fecal coliform transport as affected by surface condition. Transactions of the American
Society of Agricultural Engineers 48: 1055-1061.
Schueler, T.R., Kumble, P.A., Heraty, M.A., 1991. A current assessment of urban best management
practises and techniques for reducing non-point source pollution in the coastal zone. Review Draft.
Anacostia Restoration Team, Department of Environmental Programs, Metropolitan Washington
Council of Governments, Washington D.C., USA.
Sheridan, J. M., Lowrance, R., Bosch, D.D., 1999. Management effects on runoff and sediment
transport in riparian forest buffers. Transactions of the American Society of Agricultural Engineers
42: 55-64.
Sullivan, T., Moore, j., Thomas, D., Mallery, E., Snyder, K., Wustenberg, M., Wustenberg, J.,
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U.S. EPA, 1983. Results of Nationwide Urban Runoff Program Volume 1. Final Report. United
States Environmental Protection Agency, Office of Research and Development, National Health and
Environmental Effects Research Laboratory, Newport, Oregon, USA. PB84-185552, December
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U.S. EPA, 2000. Low Impact Development (LID): A literature review. United States Environmental
Protection Agency. Office of Research and Development, National Health and Environmental
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U.S. EPA, 2003. Procedures for the derivation of equilibrium partitioning sediment benchmarks
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Protection Agency. Office of Research and Development, National Health and Environmental
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Walsh, P.M., Barrett, M.E., Malina, J.F., Charbeneau, R.J., 1997. Use of vegetative controls for
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Young, D., 2000. Contaminant Detention in Highway Grass Filter Strips. Research report prepared
by Department of Civil and Environmental Engineering, Washington State University. Prepared for
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In: (eds) Wanielista, M.P., Yousef, Y.A., 1985. Stormwater management update. Environmental
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Yousef, Y.A., Hvitved-Jacobsen, T., Wanielista, M.P., Harper, H.H., 1987. Removal of contaminants
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Yu, S.L., 1993. Testing of best management practices for controlling highway runoff. Virginia
Transportation Research Council, Charlottesville, Virginia.
Yuan, Y., Bingber, R.L., Locke, M.A., 2009. A review of effectiveness of vegetative buffers on
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Zhang, Q., Xu, C.Y., Singh, V.P., Young, T., 2009. Multiscale variability of sediment load and
streamflow of the lower Yangtze River basin: possible causes and implications. Journal of
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Water Pollution Control Federation 61: 470-475.

Preliminary Guideline for the Determination of Buffer Zones 2014
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Annexure 16 – Guidelines for refining buffer requirements based on site
characteristics
This Annexure provides guidelines for refining buffer requirements based on site-specific buffer
zone attributes. This has been informed by a review of available literature and on the outcomes of
the hydrological sensitivity assessment undertaken for this study which specifically simulated the
effect of a suite of buffer characteristics on peak discharge (See Annexure 9).
The guideline has been developed to cater for buffer zone efficiencies associated with each of the
following threats:
• Increases in sedimentation and turbidity;
• Increased nutrient inputs;
• Increased inputs of toxic organic and heavy metal contaminants;
• Pathogen inputs.
In each case, a brief introduction is provided that outlines the key buffer zone attributes that are
known to effect buffer zone efficiencies. A table is then provided that summarizes the buffer zone
attributes used to modify buffer zone requirements which have been included in the buffer zone
model. These tables also highlight default buffer characteristics that have been assumed in the
desktop model. A rationale for selecting each criterion, together with a rationale and table for
modifiers used in the buffer zone model is then provided. Finally, a brief methodology describing
how each buffer characteristic should be assessed in the field is outlined.
1. Increases in sedimentation and turbidity
Sediment removal begins with the a reduction in the flow rate, which decreases the sediment
carrying capacity of the water causing the excess sediment to drop out of suspension (Sheldon et
al., 2003). This reduction in flow rate is caused mainly through the presence of vegetation, which
increases surface roughness, increasing the resistance to flow (Blanché, 2002). Hydrological
simulations have also clearly demonstrated that buffer zone slope and soil texture have a direct
impact on the ability of buffer zones to attenuate flows (Annexure 9). Topographic characteristics
also affect the ability of the buffer zone to effectively intercept influent water and promote deposition.
A summary of the buffer zone attributes and modifiers used to adjust buffer zone width to cater for
variability in the sediment retention capacity of buffer zones is presented in Table 1.1, below.
Further details including the rationale for considering each criteria, together with modifier ratings and
the method to be followed in collecting appropriate site-based information is detailed in the text that
follows.
Table 1.1. Buffer zone characteristics used to refine buffer zone requirements to cater for the
variability in sediment retention efficiency. Default values are highlighted in green.
Slope of the
buffer
Category Very
Gentle Gentle Moderate Moderately
steep
Stee
p
Very
steep
Score 0.6 0.75 1 1.25 1.5 1.75
Vegetation
characteristics
(basal cover)
Category Very
high High Moderately
low Low
Score 0.75 1 1.5 2

Preliminary Guideline for the Determination of Buffer Zones 2014
173
Soil
permeability
Category Low Moderately
low Moderate High
Score 1.75 1.25 1 0.75
Topography of
the buffer zone
Category
Uniform
topogra
phy
Dominantly
uniform
topography
Dominantly
Non-
uniform
topography
Concentrated
flow paths
dominate.
Score 0.75 1 1.5 2
1.1 Slope of the buffer
Rationale: A large number of authors have indicated that slope angle is a key factor in determining
sediment trapping within the buffer zone (Young et al. 1980, Peterjohn and Correll 1984, Dillaha
et al.1989, Magette et al. 1989, Phillips 1989, Hussein et al., 2007). In a recent review of a large
number of studies, Yuan, Bingner & Locke (2009) however concluded that slope does affect
sediment trapping efficiency although the relationship was weak. This weak linear relationship is
explained to some degree by a recent meta-analysis of the effectiveness of vegetated buffers
(Zhang et al., 2009) which suggests that buffer efficiency increases up to a slope of round 10%, and
then begins to decline with increasing slope angles. This finding is consistent with a review by Yuan,
Bingner & Locke (2009) which highlighted that slope becomes more important as a modifier when
slopes are greater than 5%. Indeed Sheldon et al. (2003), reported that the maximum slope should
be between 5-10 degrees to prevent concentrated flows while Blanché (2002) suggested it should
be no greater than 15 degrees. This deterioration in buffer zone effectiveness suggests that larger
buffers are required for steep slopes which is consistent with a number of review articles that
concluded that buffers need to be wider when the slope is steep, generally to give more time for the
velocity of surface runoff to decrease (Barling & Moore 1994, Collier et al. 1995; Parkyn, 2004).
Modifier ratings: From the literature, it is clear that there is negative relationship between slope
and buffer effectiveness at slopes greater than c.a. 10%. Other research does however indicate
that buffer zones remain highly effective with slopes up to 20% (Hook, 2003). Based on available
literature and results of the hydrological sensitivity analysis, buffer modifiers ranging from 0.6 to 1.75
have been proposed for different slope classes (Table 1.2).
Table 1.2. Buffer zone modifier based on slope steepness
BUFFER
CHARACTERISTIC SLOPE CLASS DESCRIPTION MODIFIER
RATING
Slope of the buffer zone
Very Gentle 0-2% 0.6
Gentle 2.1-10% 0.75
Moderate 10.1-20% 1
Moderately steep 20.1-40% 1.25
Steep 40.1-75% 1.5
Very steep >75% 1.75
Method: Use a 1: 10 00 topographic map or GIS with contour data of the study area to measure the
steepest slope of the potential buffer associated with the proposed development (apply to area
within c.a.50vm of the edge of the water resource). Slope is calculated by measuring the ratio of the
horizontal distance between the lowest and highest contour on each slope and the vertical distance
(difference between contour elevations). Slope is expressed as a percentage (for example: if the

Preliminary Guideline for the Determination of Buffer Zones 2014
174
horizontal distance is 50 m and the vertical distance is 0.5 m then the slope = 0.5 ÷ 50 x 100% =
1%). If the steepest slope is less that 2%, all other slopes will be less than this, so no further
calculations are required. If the slope is >2%, break the boundary of the water resource into units of
variable slope classes as reflected in Table 1.2.
1.2 Vegetation characteristics
Rationale: Vegetation mechanically filters runoff, causing sediment to be deposited in the buffer
zone. The more suitable the vegetation is at slowing flows and mechanically intercepting sediment,
the more effective the buffer zone is therefore likely to be.
A range of different vegetation characteristics were considered to inform buffer zone effectiveness
by reviewing a number of studies that considered the effect of vegetation variables on buffer
function. Although vegetation type may be considered a useful surrogate, Yuan, Bingner & Locke,
(2009) found that overall, sediment trapping efficiency did not vary by vegetation type with both
grass buffers and forest buffers having similar sediment trapping efficiencies. This is supported by
Lowrance et al. (1998) who reported that forested buffers are good at removing sediments (>90%
effective) from upstream flooding whilst grass is just as effective but may provide a more useful
cover in areas of concentrated flow (Barling and Moore, 1994). Hook (2003) provides some
alternatives, suggesting that vegetation characteristics such as biomass, cover, or density are more
appropriate than stubble height for judging capacity to remove sediment from overland runoff (Hook,
2003). The most useful suggestion is perhaps made in a report by Biohabitats Inc. (2007) which
suggests that robustness and density of vegetation, is an appropriate indicator since this has a
direct impact on flow rate, encouraging deposition of sediment as well as minimising streambank
erosion. This is certainly supported by a study by Van Dijk et al. (1998), where differences between
retention by grass strips was attributed mainly to differences in grass density. This is consistent
with results obtained by Hook (2003) who noted that dense vegetation of moist and wet riparian
sites generally retained sediment effectively, whereas lower sediment retention was associated with
sparse vegetation. The number of tillers or shoots was also identified as an important factor in
trapping sediment in a recent study of sediment trapping and transport on steep slopes in the
French Alps (Isselin-Nondedeu & Bédécarrats, 2007)
Modifier ratings: Although few studies have specifically related vegetation density to sediment
trapping efficiency, an experimental study of filter strip efficiency by Jin & Romkens (2001) does
provide some insights. Their findings showed that trapping efficiency increased with vegetation
density. More specifically, they found that when the density of filter strips increased from 2,500 to
10,000 bunches/m2, the trapping efficiency increased by about 45%. Other studies do however
suggest that the importance of vegetation density declines with increasing buffer width (e.g. Hook,
2003). The hydrological sensitivity analysis also provides some useful insights suggesting that a
well vegetated buffer zone of 30 m can reduce quickflows by two and a half times relative to bare
soil (See Annexure 9). Based on the information at hand, buffer modifiers ranging from 0.75 to 2.0
have been proposed for different vegetation characteristics (Table 1.3)

Preliminary Guideline for the Determination of Buffer Zones 2014
175
Table 1.3. Buffer zone modifier based on vegetation characteristics
BUFFER
CHARACTERISTIC CLASS DESCRIPTION MODIFIER
RATING
Vegetation
characteristics
Very high
Very dense vegetation, with very
high basal cover (e.g. vetiver grass
filter strips).
0.75
High Dense vegetation, with good basal
cover (e.g. natural grass stands) 1
Moderately low
Moderately low density with
moderate basal cover (e.g. Forests,
shrub dominated vegetation / heavily
grazed grassland)
1.5
Low Sparse vegetation cover with large
areas of bare soil 2.0
Method: Assess current vegetation characteristics including basal cover of vegetation within the
proposed buffer zone and rate accordingly.
Note: For the construction phase, the assessment should be based on current vegetation attributes.
In situations where the buffer is degraded, simply “protecting” a buffer with a set width may fail to
provide the necessary characteristics to protect adjacent water resources. As such, management
should aim to restore the buffer to a more naturally vegetated condition through the operational
phase. The applicant does however have the option of improving the existing buffer in order to
minimize buffer requirements or foregoing buffer restoration and providing a wider but poorly
vegetated buffer. If buffer restoration is adopted, the buffer should ideally be vegetated with native
plant communities that are appropriate for the ecoregion or with a plant community that provides
similar functions. Depending on the agreed approach, the appropriate class should be selected to
calculate operational phase buffer zone requirements.
1.3 Soil properties
Rationale: There is good scientific evidence to suggest that soil properties of areas adjacent water
resources can have a significant bearing on the level of sediment entering such systems. Soil
characteristics affect soil drainage which has a direct bearing on time taken for soil saturation to
occur and therefore surface runoff that carries soil particles.
Soil texture also determines the size of soil particles washed off exposed areas. This may have a
major bearing on buffer zone effectiveness, with fine particles being held in suspension far more
easily than course sediment and therefore being washed more easily through a buffer zone. Indeed,
Pearce et al. (1998) found that sediment yields from a riparian zone were greater when finer silica
sediments were introduced to overland flow than when coarser sandy loam sediment was
introduced. This is consistent with Syversen (2005), who found that the trapping efficiency of buffer
zones was higher for coarse particles than for fine ones with coarse clay trapped in the buffer zone
independent of its width, while the silt and sand fractions were mostly trapped in the upper part of
the buffer zone. They also found an increasing content of clay particles in runoff from the soil to
runoff throughout the buffer zone. In a simulation study on vegetated filter strips by Abu-Zreig (2001)
results also showed that inflow sediment class had a major influence on sediment trapping

Preliminary Guideline for the Determination of Buffer Zones 2014
176
effectiveness. The trapping efficiency of clay sediments in a 15 m length filter strip was 47%
compared with 92% for silt from incoming sediment.
Soil texture within the buffer zone also affects infiltration and therefore the likelihood of water flow
velocity being reduced as it moves through the buffer zone. This is particularly true for finer clay
particles, as the more the water infiltrates the more fine sediment is trapped in the soil profile
(Blanché, 2002). Buffers with coarse-grained, well drained and organic rich soils are thus more
effective at removing sediment by infiltration than those in areas with fine grained, poorly drained
and organic poor soils (Kent, 1994). This is because the hydraulic conductivity of coarse grained soil
is high (Reichenberger et al., 2007), allowing large volumes of runoff to infiltrate. It should be noted
however that although the infiltration capacity of the soil is determined mainly by its texture and
associated conductivity it also increases with increasing soil structure and the presence of macro
pores at the surface. Thus, clay soils with abundant macro pores, such as shrinking cracks and
earthworm channels, can exhibit high infiltration capacities (Reichenberger et al., 2007).
Although a range of soil characteristics could be used as an indicator of the risks associated with
sediment entering into a buffer and being removed, soil permeability is perhaps the most
appropriate measure. Soils with a high permeability (typically coarse-grained) and good infiltration
capacity will generally trap and remove sediments more effectively. Soils with low permeability
(typically fine grained) give rise to finer sediments and have lower infiltration capacities, reducing
buffer zone effectiveness.
Modifier ratings: The hydrological sensitivity assessment showed that soil texture has a moderate
impact on quick flows, with reductions of close to 25% anticipated for sandy soils relative to clay-
loam soils. Flows can increase by as much as 75% in fine-textured clay soils (See Annexure 9).
When considered together with the findings of the literature review outlined above, buffer modifiers
ranging from 0.5 to 2 have been proposed for soils with different permeability (Table 1.4).
Table 1.4. Buffer zone modifier based on soil properties/characteristics
BUFFER
CHARACTERISTIC CLASS DESCRIPTION MODIFIER
RATING
Soil permeability
Low Fine textured sols with low permeability
(e.g. clay loam and clay). 1.75
Moderately low Moderately fine textured soils (e.g. loam) 1.25
Moderate Moderately textured soils (e.g. sandy loam). 1
High Deep well-drained soils (e.g. sand and
loamy sand). 0.75
Method: Take a sample of the soil in the buffer zone or up-slope area and use the following
technique to assess soil texture: Take a teaspoon-size piece of soil and add sufficient water to work
it in your hand to a state of maximum stickiness, breaking up any lumps that may be present. Now
try to form the soil into a coherent ball. If this is impossible or very difficult (i.e. the ball collapses
easily) then soil is sand or loamy sand. If the balls forms easily but collapses when pressed between
the thumb and the fore-finger then soil is sandy loam. If the soil can be rolled into a thread but this
cracks when bent then soil is loam. If the thread can be bent without cracking and it feels slightly
gritty then soil is clay loam, but if it feels very smooth then soil is clay. Once soil texture has been
established, use this information, together with observations of soil surface conditions (e.g. shrinking
cracks, earthworm channels) to place the soils into one of three classes.

Preliminary Guideline for the Determination of Buffer Zones 2014
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Note: A more comprehensive guide for assessing soil texture is included in Ollis et al. (2013): Refer
to Section 7.4.2 and particularly “Box 24: How to determine soil texture in the field” P55 of OLLIS,
D.J., SNADDON, C.D., JOB, N.M. & MBONA, N. 2012. Classification System for wetlands and other
aquatic ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22.
South African National Biodiversity Institute, Pretoria.
1.4 Topography of the buffer
Rationale: Topography has an influence on the rate at which runoff flows over the landscape.
Uniform topography with few areas where runoff can concentrate to form erosion gullies will lead to
uniform movement across the buffer zone. Where local topography concentrates flows and
increases runoff velocity, buffer zones are likely to be less effective. This is supported by Helmers
et al. (2005) who found through modelling that as the convergence of overland flow increases,
sediment trapping is reduced. Buffers should therefore be widened in areas where concentrated
flows are anticipated, resulting in a non-uniform buffer width along the length of the water resource.
Modifier ratings: Dosskey et al. (2002) studied four farms in Nebraska, USA, to develop a method
for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that
this has on sediment trapping efficiency. Riparian buffers averaged 9-35 m wide and 1.5-7.2 ha in
area, but the effective buffer area that actually contacted runoff water was only 0.2-1.3 ha due to the
patterns of topography preventing uniform distribution of runoff. Using mathematical relationships, it
was estimated that between the four farms, buffers could theoretically remove 41-99% of sediment,
but because of non-uniform distribution it was estimated that only 15-43% would actually be
removed. These results reflect the extent of concentrated flows and its subsequent impact on
sediment-trapping efficiency. In another study by Blanco-Canqui et al. (2006), they showed that the
effectiveness of 0.7 m grass filter strips was reduced from 25% to 10% for reducing sediment when
interrill flow became concentrated flow. This suggests that buffer widths may need to be increased
significantly where local topography encourages concentrated flows (Table 1.5).
Table 1.5. Buffer zone modifier based on topography of the landscape
BUFFER
CHARACTERISTIC CLASS DESCRIPTION MODIFIER
RATING
Topography of the
buffer zone
Uniform
topography
Smooth topography with no concentrated
flow paths anticipated. 0.75
Dominantly
uniform
topography
Dominantly smooth topography with
few/minor concentrated flow paths to
reduce interception.
1
Dominantly Non-
uniform
topography
Dominantly irregular topography with some
major concentrated flow paths (i.e. erosion
gullies, drains) that will substantially reduce
interception.
1.5
Concentrated flow
paths dominate.
Area of topography dominated by
concentrated flow paths (i.e. depression,
erosion gullies, drains)
2.0
Method: Use a 1: 10 00 topographic map or GIS with contour data of the study area to assess the
general topography of landscape and identify potential concentrated flow paths. Use this, together

Preliminary Guideline for the Determination of Buffer Zones 2014
178
with on-site observations, to rate the potential impact of topography on buffer effectiveness. This
may require areas with different topographic characteristics to be mapped and assessed separately.
2. Increased nutrient inputs
Barling and Moore (1994) maintain that up to 97% of Nitrates and 78% of Phosphates in runoff is
sediment bound. Blanché (2002) also notes that one of the common factors affecting uptake of N
and P is the time they spend in the buffer zone. This is mainly linked to infiltration since the
infiltration rate of the soil must be such that it enables water to be stored in the soil for a long
enough period for effective plant uptake and chemical immobilisation processes to occur (Blanché,
2002). Effective infiltration is achieved by buffer characteristics that cause a reduction in the flow
rate, similar to those needed for sediment removal; this includes slope, type and amount of flow,
infiltration rate, buffer width, soil characteristics and the type and condition of the vegetation (Kent,
1994). Slow shallow lateral subsurface and uniform surface flow were found by Blanché (2002) to
be the most effective as they increase the time spent by the runoff in the buffer zone, allowing more
effective infiltration. Barling and Moore (1994) found that uniform flows were 61-71 and 70-95%
more effective at removing N and P, respectively, than concentrated flows, which allowed only a
small percentage of the fast flowing water to percolate into the root zone and be taken up by the
plants (Kent,1994). This means buffer zones and the upland areas above them with lower slopes
(Blanché, 2002) and smoother topography (Kent ,1994), which are less likely to cause concentrated
flows, will have better nutrient attenuation abilities (Barling and Moore, 1994).
Given that the most important mode of nutrient removal is via the co-deposition of nutrients with
sediments buffer zone criteria used for sediment trapping are also included in this assessment
(Table 2.1). Details of these criteria with further details of the relationships of these attributes with
nutrient absorption are detailed in the text that follows.
Table 2.1. Buffer zone characteristics used to refine buffer zone requirements to cater for the
variability in nutrient removal efficiencies. Default values are highlighted in green.
Slope of the
buffer
Category Very
Gentle Gentle Moderate Moderately
steep Steep Very
steep
Score 0.6 0.75 1 1.25 1.5 1.75
Vegetation
characteristics
(basal cover)
Category Very
high High Moderately
low Low
Score 0.75 1 1.5 2
Soil
permeability
Category Low
Moderately
low Moderate High
Score 1.5 1 1 1
Topography of
the buffer zone
Category
Uniform
topogra
phy
Dominantly
uniform
topography
Dominantly
Non-
uniform
topography
Concentrated
flow paths
dominate.
Score 0.75 1 1.5 2

Preliminary Guideline for the Determination of Buffer Zones 2014
179
2.1 Slope of the buffer
Rationale: The importance of buffer slope in affecting flow rate and sediment retention has been
described in section 1.1. Given the close relationship between sediment and nutrient retention,
buffer slope is regarded as equally important for nutrient uptake.
Modifier ratings: The same modifiers are applied as used for sediment retention (Table 2.2).
Table 2.2. Buffer zone modifier based on slope steepness
BUFFER
CHARACTERISTIC SLOPE CLASS DESCRIPTION MODIFIER
RATING
Slope of the buffer zone
Very Gentle 0-2% 0.6
Gentle 2.1-10% 0.75
Moderate 10.1-20% 1
Moderately steep 20.1-40% 1.25
Steep 40.1-75% 1.5
Very steep >75% 1.75
Method: As described in section 1.1
2.2 Vegetation characteristics
Rationale: The importance of buffer slope in affecting flow rate, promoting infiltration and sediment
retention has been described in section 1.1. Once infiltration has occurred, other plant
characteristics affect the amount of uptake that can occur from the subsurface flows. These include
the density, structure and condition of the vegetation. Interestingly, vegetation type was shown to
not be a significant factor in a recent meta-analysis of Nitrogen Removal efficiencies in riparian
buffers (Mayer et al., 2007). This is supported by a recent study by Syverson, 2005 whose results
showed no significant differences between forest buffer zones (FBZ) and grass buffer zones (GBZ)
regarding their retention efficiency for nitrogen and phosphorus.
Between buffers with similar vegetation types, though, species composition may also play an
important role, with Basnyat et al. (1999) reporting that native and non-native vegetation with similar
structure and density had vastly different nutrient uptake levels species. This is supported by
Richardson and Van Wilgen (2004), who showed that in the Western Cape Port Jackson willows
(Acacia saligna) changed the nutrient dynamics and cycling of the soil relative to the natural fynbos
vegetation. The productivity of different species or vegetation types is also a major factor in
determining nutrient uptake and plants with high productivity, especially annuals, are regarded as
most efficient at removing nutrients, by uptake. Thus the more annuals there are in the vegetation
the better its nutrient removal ability will be (Chapman and Kreutzwiser, 1999). However, as these
plants are annual, they will release these nutrients as they decompose, but because they take up
nutrients mostly in spring and summer, when downstream ecological systems are most biologically
active, they do help retain nutrients when the river is most active (Chapman and Kreutzwiser, 1999).
Therefore the plant uptake ability is affected by season, with less nutrients being taken up during
the winter, when plants are dormant, allowing more nitrates to escape into the water body (Gilliam,
1994). In many such cases trees would therefore be more effective as they remain active deep
underground during winter, taking up nutrients. This was supported by Haycock and Pinay (1993),
who showed that poplars were more effective than grasses at removing nutrients during the winter

Preliminary Guideline for the Determination of Buffer Zones 2014
180
(summer rates were almost equal) in England, as they remain more active and intercept more runoff
due to their roots penetrating deep into the soil.
It is also worth noting that vegetation biomass has an impact on nutrient uptake efficiency. Indeed,
the greater the biomass, the greater the provision of microhabitat and organic matter critical for soil
microbes involved in the assimilation of nutrients from influent water. In addition, the greater the
vegetation biomass, the greater will be the potential for direct assimilation of nutrients by plants. It
is recognized, however, that at the end of the growing season significant amounts of nutrients taken
up by the plants may be lost through litterfall and subsequent leaching, although this is limited by
the translocation of nutrients to the belowground storage portions of the plant (Hemond and Benoit,
1988).
Note: Because of the different modes of particulate and dissolved contaminant transport, multi-tier
or combination buffers are often advocated. A narrow combination buffer consisting of 5 m of grass
filter strip and a 1 m wide row of deciduous trees significantly reduced nitrate in subsurface flows
beneath cropland in Italy (Borin & Bigon 2002). A substantial reduction in nitrate (average 81%) was
observed at the field/grass buffer boundary and the authors concluded that the roots of the trees
were extending beyond the combined 6 m buffer so that the zone of influence was larger than the
land that was retired from use. Further reductions in nitrate were measured through the buffer and
discharge to the stream had concentrations that were less than 2 ppm.
Despite these complexities, it is clear that vegetation plays an important role in nutrient removal. To
prevent complicating the assessment, the vegetation characteristics used for sediment trapping are
regarded as relevant and have been included for nutrient retention effectiveness.
Modifier ratings: The same modifiers are applied as used for sediment retention (Table 2.3).
Table 2.3. Buffer zone modifier based on vegetation characteristics
BUFFER
CHARACTERISTIC CLASS DESCRIPTION MODIFIER
RATING
Vegetation
characteristics
(basal cover)
Very high
Very dense vegetation, with very
high basal cover (e.g. vetiver grass
filter strips).
0.75
High Dense vegetation, with good basal
cover (e.g. natural grass stands) 1
Moderately low
Moderately low density with
moderate basal cover (e.g. forests,
shrub dominated vegetation / heavily
grazed grassland)
1.5
Low Sparse vegetation cover with large
areas of bare soil 2.0
Method: As described in section 1.2

Preliminary Guideline for the Determination of Buffer Zones 2014
181
2.3 Soil properties
Rationale: The importance of buffer slope in affecting flow rate and sediment retention has been
described in section 1.1. Given the close relationship between sediment and nutrient retention, soil
properties have also been included as a modifier for nutrient uptake efficiency.
It is worth noting though that although soils with high permeability generally provide greater filtration
of sediment and attached pollutants, highly permeable soils such as sandy soils, may allow for the
rapid movement of water into the groundwater. The movement may be so rapid that no removal of
pollutants is allowed by plants, and only minimal removal by physical and chemical adsorption. The
better aeration of these sandy soils is also unfavourable to denitrification as it increases the
oxidation/reduction potential. This was well illustrated by Groffman & Tiedje (1989) who found that
well-drained soils were only half as effective at removing nitrogen as poorly drained soils. Sandy
soils provided the least nitrogen removal, regardless of drainage capacity (Groffman & Tiedje,
1989). This was further supported by a study by Ehrenfeld (1987) who found that nitrogen from
septic system leachate moved greater distances vertically than horizontally through permeable
sandy soils, percolating quickly below the root zone of buffer vegetation. Poorly drained soils on the
other hand, generally retain water long enough, and often under conditions favourable enough that
pollution removal is accomplished (Desbonnet et al., 1994)
Clay soils are also unfavourable for nutrient attenuation, due to their low permeability, reducing the
amount of infiltration that occurs. Apart from the effect on infiltration, the size of sediment particles
in the buffer zone also influences its nutrient removal ability, as the greater surface area created by
smaller particles retains far more nutrients than coarser grained sediment. Soils with high clay
content, but not high enough to prevent infiltration, are therefore much better at filtering nutrients,
which can then be removed by plant uptake or denitrification. Indeed, when mixed clay soils are
present, water is retained for longer and organic content is high, resulting in optimum levels of
denitrification (Blanché, 2002). Of further benefit is the increased denitrification during drier times,
caused by the good water retention properties of these soils that maintain anaerobic conditions for
longer periods (Blanché, 2002). Mixed-clay soils are therefore regarded as most effective in
pollutant removal (Desbonnet et al., 1994).
Modifier ratings: Based on the literature review, it is clear that the primary mechanism of
phosphorous removal is co-deposition with sediments. As such, buffer zone attributes that promote
sediment attenuation are best suited for phosphorous removal. The relationship between soil
properties and nitrogen removal is more complicated with course soils being well suited for the
nutrient removal of sediments attached nutrients while poorly drained soils, on the other hand,
create favourable conditions for denitrification, by promoting the formation of anaerobic conditions.
Thus soils with moderate drainage would enable co-deposition of nutrients and denitrification
(Blanché, 2002). Taking these factors into account, together with the reported dominance of
sediment-bound pollutants, modifiers have been adjusted slightly for nutrient removal (Table 2.4).

Preliminary Guideline for the Determination of Buffer Zones 2014
182
Table 2.4. Buffer zone modifier based on soil properties/characteristics
BUFFER
CHARACTERISTIC CLASS
DESCRIPTION MODIFIER
RATING
Soil permeability
Low Fine textured sols with low permeability
(e.g. clay loam and clay). 1.5
Moderately low Moderately fine textured soils (e.g. loam) 1
Moderate Moderately textured soils (e.g. sandy
loam). 1
High Deep well-drained soils (e.g. sand and
loamy sand). 1
Method: As described in section 1.3
2.4 Topography of the buffer
Rationale: The importance of topography in affecting flow rate and sediment retention has been
described in section 1.1. Given the close relationship between sediment and nutrient retention,
topography has also been included as a criterion for nutrient assimilation.
Modifier ratings: The same modifiers are applied as used for sediment retention (Table 2.5).
Table 2.5. Buffer zone modifier based on topography of the landscape
BUFFER
CHARACTERISTIC CLASS DESCRIPTION MODIFIER
RATING
Topography of the
buffer zone
Uniform
topography
Smooth topography with no concentrated
flow paths anticipated. 0.75
Dominantly
uniform
topography
Dominantly smooth topography with
few/minor concentrated flow paths to
reduce interception. 1
Dominantly Non-
uniform
topography
Dominantly irregular topography with
some major concentrated flow paths (i.e.
erosion gullies, drains) that will
substantially reduce interception.
1.5
Concentrated flow
paths dominate.
Area of topography dominated by
concentrated flow paths (i.e. depression,
erosion gullies, drains)
2.0
Method: As described in section 1.4
3. Water quality – Increased toxic contaminants
Removal efficiencies for sediment-attached and dissolved toxics are likely to be similar to those
determined for sediments and dissolved nutrients (Blanche, 2002). Literature also highlights the
differences with respect to organic pollutants and pesticides, and metals. These two broad
categories have been considered for refining buffer requirements at a site-based level. Site-based
characteristics applicable for the removal of sediments and nutrients were considered appropriate
for refining buffer zone requirements to cater for the variability in toxic organic and metal
contaminant retention efficiency.

Preliminary Guideline for the Determination of Buffer Zones 2014
183
A summary of the buffer zone attributes and modifiers used to adjust buffer zone width to cater for
variability in toxic organic and metal contaminant retention efficiency of buffer zones is presented in
Table 3.1, below. For further details including the rationale for considering each criteria, together
with modifier ratings and the method to be followed in collecting appropriate site-based information,
please see Section 1.
Table 3.1. Buffer zone characteristics used to refine buffer zone requirements to cater for the
variability in toxic organic and metal contaminant retention efficiency. Default values are highlighted
in green.
Slope of the
buffer
Category Very Gentle Gentle Moderate Moderately
steep Steep Very
steep
Score 0.6 0.75 1 1.25 1.5 1.75
Vegetation
characteristics
(basal cover)
Category Very high High Moderately
low Low
Score 0.75 1 1.5 2
Soil
permeability
Category High Moderate Moderately
low Low
Score 0.75 1 1.25 1.75
Topography of
the buffer
zone
Category Uniform
topography
Dominantly
uniform
topography
Dominantly
Non-
uniform
topography
Concentrated
flow paths
dominate
Score 0.75 1 1.5 2
4. Water quality – pathogens (i.e. disease-causing organisms)
The primary mechanism for the removal of micro-organisms in runoff, though, is infiltration (Tate
et al., 2004). This is usually coupled with their adsorption to soil particles, hindering their passage to
the water body, resulting in their eventual death. As with sediment retention functions, the velocity
of the contaminated water entering and flowing through the buffer is therefore regarded as a
particularly important attribute in affecting the ability of buffers to remove pathogens. Some micro-
organisms are in fact attached to the sediment and deposited with sediment, just as with sediment
attached nutrients and other toxics (Kent, 1994). Many, however, are suspended freely in the runoff
and to be removed they must settle out from the solution, through a reduction in flow rate, just as
with sediments (Kent, 1994). They may then infiltrate into the soil and/or adsorb to soil or organic
material (Tate et al., 2004).
Increased velocity increases the detachment and flushing transport or micro-organisms from
substrates in the upland and buffer areas, increasing the amount delivered to the water body (Tate
et al., 2004). This is illustrated in an investigation on the rate of Cryptosporidium parvum oocyst
delivery to a water body, across a buffer by Tate et al. (2004) who demonstrated that the rate of
delivery was related to the velocity of the surface runoff. With increasing velocity, the micro-
organisms became dislodged more easily from the substrate, resulting in greater concentrations
entering the water body.
Besides influencing their transport, runoff also influences micro-organism mortality, which is largely
due to desiccation (Biohabitats Inc., 2007) and therefore the link between runoff velocity and
residence time is also important in determining micro-organism removal (Kent, 1994). In this regard,

Preliminary Guideline for the Determination of Buffer Zones 2014
184
Kent (1994) found that even a short residence time can vastly reduce the number of pathogens. He
showed that even though domestic sewage in a particular study originally contained more
pathogens than stormwater runoff, the stormwater contributed more pathogens to the water body.
This is because it delivered water at a higher velocity, giving little time for the desiccation or death of
the pathogens to occur, whilst the sewage was delivered at a far slower velocity, resulting in the
desiccation and death of a larger portion of the pathogens. He then demonstrated that just 7 m of
buffer was needed to reduce both these amounts to an acceptable level.
For parasitic oocytes, such as Cryptosporidium parvum (a diarrheal disease mainly spread by
recreational water activities) however, they may not die, but must be retained in the buffer during
their ‘infective stage’ so as to not contaminate the water body (Tate et al., 2004).
Removal of pathogenic micro-organisms therefore typically requires similar buffer attributes as that
for sediment retention including gentle slope, slow uniform flow, dense vegetation and good soil
permeability. As such, the criteria and associated attributes used to assess sediment retention
efficiency have been used to inform buffer requirements for pathogen removal.
A summary of the buffer zone attributes and modifiers used to adjust buffer zone width to cater for
variability in the pathogen retention efficiency of buffer zones is presented in Table 4.1, below. For
further details including the rationale for considering each criteria, together with modifier ratings and
the method to be followed in collecting appropriate site-based information, please see section 1.
Table 4.1. Buffer zone characteristics used to refine buffer zone requirements to cater for the
variability in pathogen retention efficiency. Default values are highlighted in green.
Slope of the
buffer
Category Very Gentle Gentle Moderate Moderately
steep Steep Very
steep
Score 0.6 0.75 1 1.25 1.5 1.75
Vegetation
characteristics
(basal cover)
Category Very high High Moderately
low Low
Score 0.75 1 1.5 2
Soil
permeability
Category High Moderate Moderately
low Low
Score 0.75 1 1.25 1.75
Topography of
the buffer zone
Category Uniform
topography
Dominantly
uniform
topography
Dominantly
Non-
uniform
topography
Concentrated
flow paths
dominate
Score 0.75 1 1.5 2
15. Potential criteria not included in this assessment
It is worth noting that a range of additional factors also affect the ability of buffer zones to reduce
pathogen loads but have not been specifically integrated into the model. These are detailed briefly
here:
• Soil moisture: Soil moisture levels may also affect buffer zone effectiveness as desiccation is
a large contributor to pathogen mortality. Drier soils promote water absorption and desiccation
(Biohabitats Inc., 2007) and are therefore generally more effective than moist soils for pathogen

Preliminary Guideline for the Determination of Buffer Zones 2014
185
removal. To illustrate this point, hookworm disease (Strongyloidiasis) and threadworm can
survive in the film of moisture surrounding soil particles. Buffer zones with drier soils will carry
less of these parasites, reducing infection rates (Cowan, 1995).
Studies also show that the pathogen removal ability of the buffer is mainly dependent on the
physiochemical interactions that occur between the soil and the pathogen. The different
chemical characteristics of different soil types will promote the adsorption of different types of
pathogens, some pathogens, such as Cryptosporidium parvum can actively desorb themselves
from particles (Tate et al., 2004).
• Size and shape of pathogens: This also plays a role, with small narrow types, such as E. coli
and Salmonella being far more difficult to remove as they can escape entrapment far more
easily than larger cylindrical types, including parasitic oocytes (Tate et al., 2004).
• Survivability: Even once caught, the survivability of the micro-organisms influences the buffers
effectiveness at removing them, as some micro-organisms may survive up to 27 weeks in the
soil, enabling them to possibly be dislodged once again and delivered to the water body (Kent,
1994).
It is important to note that while these attributes have not been specifically accounted for, Tate et al.
(2004) agree that when factoring out the attributes specific to the type of micro-organism that
attributes that promote sediment retention including slow flow, greater infiltration and filtration should
be the primary buffer zone characteristics considered when aiming to remove microbes in general.
This is consistent with the approach followed in this method.
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Annexure 17 – Overview of the mitigation measures tool
An Excel tool was developed as part of this project to help assessors identify a suite of alternative
mitigation measures and management guidelines that can be used to reduce potential impacts on
aquatic ecosystems. This tool was developed by Mr. Douglas Macfarlane with input from Mr.
Jeremy Dickens and was based on a review of close to seventy best-practice guidelines across a
range of sectors.
The tool is designed to act as a quick reference for assessors to a wide range of mitigation
measures and guidelines which would otherwise need to be accessed through a plethora of
different guidelines. References are also linked to specific mitigation measures to help users
access relevant supporting documentation if required. The tool is structured according to nine
primary threats which are also assessed as part of the buffer zone determination process. These
include:
• Alteration to flow volumes;
• Alteration of patterns of flows (increased flood peaks);
• Increase in sediment inputs & turbidity;
• Increased nutrient inputs;
• Inputs of toxic contaminants (including organics & heavy metals);
• Alteration of acidity (pH);
• Increased inputs of salts (salinization);
• Change (elevation) of water temperature; and
• Pathogen inputs (i.e. disease-causing organisms).
The tool includes a list of some 370 mitigation measures that can be used to reduce impacts to
aquatic ecosystems and is simply structured to facilitate use. Filters have been set up to allow
users to quickly search through the range of mitigation measures for those that are relevant to them.
Filters are structured according to the following criteria and can be filtered accordingly:
• Aspect: This groups mitigation measures based on common themes such as construction
management; site planning; mine management; pollution control and rehabilitation. This allows
mitigation measures of a similar type to be quickly located and reviewed.
• Relevance of management guideline / mitigation measure: This allows users to filter
mitigation measures based on a selected threat type such as “Increase in sediment inputs &
turbidity”. Differentiation is made here between mitigation measures with strong relevance and
those mitigation measures which may contribute towards mitigating selected threat types but
which are not specifically designed to do so.
• Construction Phase: This allows users to identify mitigation measures which are specifically
designed to address construction-phase impacts. These are grouped according to sector to
enable easy access to relevant mitigation measures. In this way, a simple filter can be set up to
search for construction-related mitigation measures for any sector such as “Agriculture” or
“Mining”.
• Operational Phase: As above, but here, mitigation measures relevant to operational activities
can be quickly filtered.
While the tool does not represent an exhaustive suite of mitigation measures / management
guidelines, it certainly covers a wide variety of these and will help any assessor in better
understanding potential mitigation measures that can be used to mitigate potential impacts.

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Annexure 18 – Examples of biodiversity information sheets (electronic
copy only – refer to the CD provided)
Annexure 19 – Guidelines for corridor design (electronic copy only –
refer to the CD provided)
Annexure 20 – Useful data layers (electronic copy only – refer to the CD
provided)

TT 610/14
TT 610/14 - Preliminary Guideline for the Determination of Buer Zones for Rivers, Wetlands and Estuaries
Preliminary Guideline for the
Determination of Buffer Zones
for Rivers, Wetlands and Estuaries
CONSOLIDATED REPORT
DM Macfarlane, IP Bredin, JB Adams, MM Zungu, GC Bate & CWS Dickens