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Coastal Risk Management in a Changing Climate
Abstract
It is increasingly recognized that a comprehensive understanding of the existing flood system is necessary to effectively manage coastal flood risk. This involves consideration of the social and ecological dimensions in addition to the hydrological aspects that have been the traditional focus of flood analysis. Social aspects are important, as they represent both the reason for flood management and the growth in exposure, as well as providing the context within which any decision will be made. Coastal species and habitats are inherently important for the flood management ecosystem services that they provide for flood management. The flood flow, depth, and extent determine the potential for flood damage. The conceptual model adopted here for coastal risk assessment is based on the Source-Pathway-Receptor-Consequence model, which is a simple linear conceptual model for representing flood systems and processes that lead to a particular flooding consequence. This approach is being used to evaluate how the Sources (waves, tides, storm surge, mean sea level, river discharge, run-off), through the Pathways (including coastal defenses), affect the Receptors (inland system), generating economic, social, and environmental Consequences. Collectively, this more holistic analysis of the flood system can identify likely trends in flood risk and the wide range of potential mitigation options embracing engineering, ecological, or socioeconomic measures, including hybrid combined approaches.
... There is much research on the limitations and strengths of each approach to adapt to a changing coastal flood risk, and there is a continued demand and interest in (coastal) flood risk governance and management becoming more holistic and integrated (Hall et al. 2003;Zanuttigh et al. 2015;Alexander, Priest, and Mees 2016;Begg 2018). Yet adaptation assessments are often still focused on structural interventions, either solely on structural protective measures (Hino, Field, and Mach 2017) or on structural defence measures (Zanuttigh 2011). ...
Coastal flooding is a major concern in England, with significant past and potential future damages. Even with climate change mitigation, the sea level will keep rising. There is a need to adapt on the coast to the changing and growing risks posed not only by a changing climate, but also a changing society. Despite the wide-held view that flood risk management (FRM) should take an integrated approach, research into coastal FRM of an interdisciplinary nature remains scarce in England. This thesis aims to address this gap, by undertaking a cross-scale analysis of national policy, organisational and household involvement in coastal FRM in England, to develop a more integrated understanding for decision-makers of the challenges facing household adapting to coastal flood risk. The thesis uses mixed methods to address three objectives: 1) evaluate synergies and challenges in national policies for managing household coastal flood risk via a StrengthWeakness-Opportunity-Threat analysis; 2) analyse the challenges and solutions in policy delivery for sub-national organisational stakeholders via thematic analysis of interviews with organisational stakeholders in the North-west and Central-south of England; and 3) characterise household motivation and participation in coastal FRM through statistical analysis of stakeholder and household surveys distributed in south Lincolnshire. This work identifies a discrepancy between policies and sub-national experiences in establishing, resourcing and sustaining long-term plans for the coast. There also remains a paucity of interactions between professions, despite the acknowledged benefits of interacting across boundaries and sectors. Sub-national organisational stakeholders could be empowered by capacity-building and financial resources to play a more effective role in the conversation, decision-making and implementation of coastal FRM. Sub-national stakeholders are ambiguous about the role of the public in FRM. This work finds that households who feel capable to act, and who are aware of local FRM, are more likely to take preparedness measures themselves. These findings contribute to establishing a more comprehensive conceptual framework for studying flood risk household action, identifying the importance of characteristics of past flood experiences, preparedness communications and responsibility perceptions. It is a critical and opportune time for policy makers to set clear goals and provide direction for the responsibility of and engagement of the public, whose role is central to any long-term adaptation. The thesis concludes that the positive trend of overcoming disciplinary boundaries in the coastal FRM governance should be accompanied by an overtopping of social barriers that limit effective sub-national stakeholder and household adaptation to coastal flood risk.
... Coastal flooding risk management therefore is urgently needed in places such as Puntarenas, where the future scenarios are not very optimistic. According to Zanuttigh, Nicholls, and Hanson (2015), strategies that address coastal hazards must be developed within a long-term and multidisciplinary vision.. Such measures are challenging and require solid political will. ...
... Flood risk management strategies are being developed with a multidisciplinary, long-term perspective, and with a fruitful discussion between scientists, stakeholders, and policy makers. This approach agrees with many recent studies, which point out that it is necessary to integrate innovative technical measures in a strategic policy context which also considers environmental, social, and economic issues (The Heinz Center and Ceres 2009;Penning-Rowsell et al. 2014;Zanuttigh 2011;Zanuttigh et al. 2014). ...
... Flood risk management strategies are being developed with a multidisciplinary, long-term perspective, and with a fruitful discussion between scientists, stakeholders, and policy makers. This approach agrees with many recent studies, which point out that it is necessary to integrate innovative technical measures in a strategic policy context which also considers environmental, social, and economic issues (The Heinz Center and Ceres 2009;Penning-Rowsell et al. 2014;Zanuttigh 2011;Zanuttigh et al. 2014). ...
... Coastal flooding risk management therefore is urgently needed in places such as Puntarenas, where the future scenarios are not very optimistic. According to Zanuttigh, Nicholls, and Hanson (2015), strategies that address coastal hazards must be developed within a long-term and multidisciplinary vision.. Such measures are challenging and require solid political will. ...
... Flood risk management strategies are being developed with a multidisciplinary, long-term perspective, and with a fruitful discussion between scientists, stakeholders, and policy makers. This approach agrees with many recent studies, which point out that it is necessary to integrate innovative technical measures in a strategic policy context which also considers environmental, social, and economic issues (The Heinz Center and Ceres 2009;Penning-Rowsell et al. 2014;Zanuttigh 2011;Zanuttigh et al. 2014). ...
... Flood risk management strategies are being developed with a multidisciplinary, long-term perspective, and with a fruitful discussion between scientists, stakeholders, and policy makers. This approach agrees with many recent studies, which point out that it is necessary to integrate innovative technical measures in a strategic policy context which also considers environmental, social, and economic issues (The Heinz Center and Ceres 2009;Penning-Rowsell et al. 2014;Zanuttigh 2011;Zanuttigh et al. 2014). ...
Sea level rise and high tide events are threatening many coastal cities, which require adequate and sustainable protection measures. The historic city centre of Venice (Italy) is often flooded during very high tide events, especially the area of St. Mark's island, which is at the lowest elevation among all the islands forming the city. In order to design cost effective protection interventions to safeguard the historical heritage, a deep understanding of flooding mechanisms and the relationship between groundwater pressure and tidal oscillations are necessary. Geotechnical survey and analyses play an important role in this process. This paper presents the results of a recent monitoring campaign carried out in St. Mark's island. A simplified one-dimensional analytical model has been derived for saturated conditions to understand the key parameters that govern tidal induced pressure oscillations in soil (material properties, geometrical features and wave properties). Additional features, such as partially saturated soil conditions and two-dimensional effects, have been investigated numerically. Results show that significant pressure oscillations occur in the subsoil, which should not be neglected for the stability of horizontal architectural structures, such as the historical mosaics and paving. However, seepage flow rate is small, thus its impact on the drainage system is limited in terms of water discharge.
Flood-induced damage in transport infrastructure (TI) is very prominent and growing rapidly with the increased establishment of human amenities within the flood-prone region of India. The estimation of actual damage of TI for flooding is now an essential task for sustainable planning in future development by reducing financial losses. The Government of India has significantly increased the share of the total GDP from 0.30 to 0.98% in the last ten years (2007–2017) for the development of the transport sector. The
regional level statistical investigation has been done to show the temporal development of road networks for the past 60 years. After normalising with the Wholesale Price Index (WPI), the financial damages by flood events have been also presented here for the same period. The result shows that the flooding area of the country has been reduced by ~40% in comparison with the severe phase of the Indian Flood (1970–1980s), whereas the damage of public utility or primarily transport infrastructure loss has been significantly increased by ~240%. Maps are also showing a positive association between higher flood-affected areas and maximum losses of public utility mainly in the states of Lower Gangetic Basin and Eastern Coast of India.
Floods are hazard which poses immense threat to life and property. Identifying flood-prone areas, will enhance flood mitigation and proper land use planning of affected areas. However, lack of resources, the sizable extent of rural settlements, and the evolving complexities of contemporary flood models have hindered flood hazard mapping of the rural areas in Ghana. This study used supervised Random Forest (RF) classification, Landsat 8 OLI, and Landsat 7 ETM + images to produce flood prone, Land Use Land Cover (LULC), and flood hazard maps of the Nasia Watershed in Ghana. The results indicated that about 418.82 km² area of the watershed is flooded every 2–3 years (normal flooding) and about 689.61 km² is flooded every 7–10 years (extreme flooding). The LULC classification produced an overall accuracy of 92.31% and kappa of 0.9. The flood hazard map indicated that land areas within hazard zones of the river include the Nasia community, Flood Recession Agricultural (FRA), rainfed and woodlands. When compared with a Modified Normalized Difference Water Index (MNDWI), the RF supervised classification had an edge over the MNDWI in estimating the flooded areas. The results from this study can be used by local administrators, national flood disaster management and researchers for flood mitigation and land use planning within the watershed.
[1] Assessments of potential impacts of climate change on water resources systems are generally based on the use of downscaled climate scenarios to force hydrological and water resource systems models and hence quantify potential changes in system response. This approach, however, has several limitations. The uncertainties in current climate and hydrological models can be large, such analyses are rapidly outdated as new scenarios become available, and limited insight into system response is obtained. Here, we propose an alternative methodology in which system vulnerability is analyzed directly as a function of the potential variations in flow characteristics. We develop a stochastic reconstruction framework that generates a large ensemble of perturbed flow series at the local scale to represent a range of potential flow responses to climate change. From a theoretical perspective, the proposed reconstruction scheme can be considered as an extension of both the conventional resampling and the simple delta-methods. By the use of a two-parameter representation of regime change (i.e., the shift in the timing of the annual peak and the shift in the annual flow volume), system vulnerability can be visualized in a two-dimensional map. The methodology is applied to the current water resource system in southern Alberta, Canada, to explore the system's vulnerability to potential changes in the streamflow regime. Our study shows that the system is vulnerable to the expected decrease in annual flow volume, particularly when it is combined with an earlier annual peak. Under such conditions, adaptation will be required to return the system to the feasible operational mode.
Bangladesh is one of the countries most vulnerable to
climate change which also has a very high population
density. The combination of a high level of poverty, and
a depleted ecological system increase the country’s
vulnerability to the impacts of climate change, which
threatens the development achievements over the last
decades. The increasing risks from climate change, sea
level rise, and natural and man-made hazards—such as
cyclones, storm surge, flooding, land erosion, water
logging, and salinity intrusion in soil and water—
already have adversely affected livelihoods of people
living in environmentally fragile areas.
The climate change-related hazards bring about multiple impacts on the communities which deteriorate their
existing conditions and increase their vulnerabilities to
further events. In order to cope and adapt to these
recurring events, the local people have adopted a variety
of mechanisms based on their indigenous knowledge
and capacities. However, these practices are not enough
to sustain their lives and livelihoods in the face of
frequent and intense natural disasters. The government,
together with assistance from local NGOs and international donor agencies, should take initiatives to increase
the adaptive capacities of the people either by reducing
their exposure to hazards and minimizing the damages
or by strengthening their asset base and thus building
their capacities.
Using the volume of fluid (VOF) method, a numerical model is developed to estimate the nonlinear dynamics of a pontoon type moored submerged breakwater under wave action and the forces acting on the mooring lines, for both the vertical and inclined mooring alignments. The model is developed for a two-dimensional wave field in a vertical plane. The finite displacements of the breakwater such as sway, heave and roll in a very small time step are considered and the numerical grid cells intersected by the breakwater surfaces for changing its position due to wave action are treated using the concept of porous body model. Also, two-dimensional experimental studies are carried out to investigate the performance of the proposed model. The comparison of the computed and measured results reveals that the developed numerical model can reproduce well the dynamics of the floating body and the mooring line forces.
Wave overtopping discharges at coastal structures are well described in the EurOtop Manual (2007), including the distribution of overtopping wave volumes. Each volume that overtops a dike or levee will have a certain flow velocity and depth record in time, often given by the maximum velocity and flow depth. This paper describes some further development of the theory on flow depth and velocities on the crest, but will also show an inconsistency with respect to the mass balance. The second part of the paper gives an analysis of measured values on real dikes, simulated by the Wave Overtopping Simulator. It gives also the method of "cumulative hydraulic load" to compare overtopping discharges for different wave conditions. A large wave height with less overtopping waves, but larger overtopping wave volumes, is more damaging than a small wave height with more, but smaller overtopping volumes, even if the overtopping discharge is similar. The reasons to develop the cumulative hydraulic load have been compared with the recently in the US developed method of erosional equivalence.
Robert Nicholls is a Professor of coastal engineering in the School of Civil Engineering and the Environment at the University of Southampton, UK. His main technical areas of interest are long-term coastal engineering and management, especially the issues of coastal impacts and adaptation to climate change, with an emphasis on sea-level rise. Nationally, he leads the coastal research program of the Tyndall Centre for Climate Change Research and has contributed to a range of projects, including the RegIS Study, the national assessment of Flood Risk and Coastal Defence, and the Stern Review of the Economics of Climate Change. Within the European Union, he was a lead investigator on the DINAS-COAST Project, which led to the development of the DIVA tool for subnational to global vulnerability assessment, and he is involved in a number of projects which are utilizing this model. Internationally, he has conducted assessments for a number of international organizations, including the Organization for Economic Co-Operation and Development (OECD) and the World Bank. He was lead author of chapters in four reports of the Intergovernmental Panel for Climate Change (IPCC): Second Assessment Report (1996); the Regional Assessment (1998); the Special Report on Technology Transfer (2000); and the Third Assessment Report (2001), and was convening lead author for the ‘Coastal systems and low-lying areas’ chapter in the IPCC 4th Assessment Report. In 2008, he was awarded the Roger Revelle Medal by the Intergovernmental Oceanographic Commission.
A comprehensive literature review on the material characteristics, design of size and shape, application and management of artificial reef has been carried out. Multipurpose Artificial Surfing Reefs (MPASR) are increasingly being adopted for coastal protection because of several advantages associated with them such as coastal protection by reducing the wave energy, recreation of beaches (surfing, fishing, and diving), habitat for marine organisms and increase in socioeconomic prosperity. The most important characteristic is that they are soft barriers. It is concluded that although artificial reefs do have the ability to fulfill many objectives, for which they are meant, their success will depend mainly on the quality of planning and management prior to their implementation.
This paper presents a new empirical relation for the shape factor in the Weibull distribution that describes the distribution of overtopping wave volumes. This improvement increases the applicable range of the Weibull distribution from very low average overtopping discharges to large discharges resulting from combined wave overtopping and steady surge overflow at negative freeboards. The effect this improvement has on wave overtopping simulation is also discussed. Measured maximum flow thicknesses, velocities, and discharges from experiments of combined wave and surge overtopping are examined to learn more about the variability of these key parameters as a function of individual overtopping wave volumes. A key finding is that wave volumes containing the 2%-exceedance value of maximum velocity typically have maximum flow thicknesses well below the 2%-exceedance level, and vice-versa. Furthermore, the 2%-exceedance hydrodynamic parameters do not occur in the 2%-exceedance wave volumes. Finally, empirical relationships are developed for several parameters that showed strong trends.
An overview of generic types of wave energy converter (WEC) is presented and their mooring requirements discussed. Mooring system configurations and components from the offshore industry suitable for WEC units are identified. Possible mooring configurations for WECs are discussed and it is argued that not only station keeping but also the overall performance characteristics of the WEC mooring should be considered in the design.
Evolution of coastal morphology over centuries to millennia (low-order coastal change) is relevant to chronic problems in coastal management (e.g., systematic shoreline erosion). This type of coastal change involves parts of the coast normally ignored in predictions required for management of coastal morphology: i.e., shoreline evolution linked to behavior of the continental shelf and coastal plain. We therefore introduce a meta-morphology, the coastal tract, defined as the morphological composite comprising the lower shoreface, upper shoreface and backbarrier (where present). It is the first order-system within a cascade hierarchy that provides a framework for aggregation of processes in modeling low-order coastal change. We use this framework in defining boundary conditions and internal dynamics to separate low-order from higher-order coastal behavior for site-specific cases. This procedure involves preparation of a data-model by templating site data into a structure that complies with scale-specific properties of any given predictive model. Each level of the coastal-tract cascade is distinguished as a system that shares sediments internally. This sediment sharing constrains morphological responses of the system on a given scale. The internal dynamics of these responses involve morphological coupling of the upper shoreface to the backbarrier and to the lower shoreface. The coupling mechanisms govern systematic lateral displacements of the shoreface, and therefore determine trends in shoreline advance and retreat. These changes manifest as the most fundamental modes of coastal evolution upon which higher-order (shorter-term) changes are superimposed. We illustrate the principles in a companion paper (The Coastal Tract: Part 2).
On the 28th of February 2010 at 2 a.m. the storm Xynthia hit the French Atlantic coast. The
storm surge combined with the high tide and large waves caused flood defences to fail along the
coastline from the Gironde (Bordeaux) to the Loire Estuary. A significant amount of land, (>50 000
ha) was consequently flooded and 47 people died as a result of the storm. Most people died due
to the flooding (they drowned, were exhausted or died from hypothermia). A number of people
died as a result of the storm itself (storm debris). The French departments of Vendée and Charente
Maritime suffered the most. Some parts of the departments Gironde and Loire Atlantique were
also flooded. Since 1953 the Netherlands has not had any experience with major floods. Large
parts of the Netherlands are also prone to coastal flooding, even though we have very high safety
standards. The Netherlands can learn from this flood in a neighbouring country with a common
history and legal system. The foundation of the legal system in the Netherlands and France was
laid down in the Napoleonic period with the introduction of the book on common law.
Jurisprudence plays a minor role in Napoleonic law. The flood was not caused by natural
phenomena alone, organisational failure plays a large role in understanding the flood.
This book describes the Xynthia storm and its consequences. Using multiple viewpoints of the
“multy-layer safety”: flood warning, flood prevention, special planning and disaster management,
this book gives lessons from the storm for the Netherlands.
Please note: We have used all available public sources up to the beginning of August 2010. The
official facts about the storm have been assembled in three French public enquiries, by each
house of parliament and by the French ministry of Ecology, Energy Transport and Development
MEEDEM. Our purpose is to give lessons for the Netherlands and not to give a perfect list of facts
about the storm.
The Dutch, French and English versions differ slightly. Some background information has been
added in each language.
The purpose of this contribution is the representation of real wave overtopping over sea dikes with the Rans-Vof code (IH-2VOF) developed by the University of Cantabria. More specific objectives are: to identify the real capacity of the IH-2VOF model in the prediction of overflow and to determinate the accuracy of these predictions in order to provide designers with a generally applicable methodology to use the code. The model is validated against experimental tests conducted by Hughes at the U.S. Army Engineer Research and Development Center (ERDC). This analysis shows that the model tends to overestimate wave reflection and better results are obtained by introducing a porous layer around the structure as artificial way to reduce reflected wave energy.
This study develops a DPSIR (" Drivers, " " Pressures, " " States, " " Impacts " and " Responses ") model to elucidate the relations between hazard, risk and society. The DPSIR model places emphasis on current state as well as time and change. In addition, it talks about chains of causation which helps us understand different types of causes of disasters. This study compares its proposed model to similar models by UNEP etc. Three major advantages of the model proposed in this study are: (1) Theoretically, the model adds to the literature of disaster risk by combining the idea of DPSIR and disaster risk; (2) Practically, this study provides suggestions regarding how to implement the DPSIR model. It suggests starting from Impacts when analyzing historical cases and beginning from Drivers, Pressures and States when studying potential impacted zones without disaster experience; (3) Practically, the model helps researchers explore causes of disaster and inspect risk management strategies from different angles (" Drivers, " " Pressures, " or " States ").
The design of a mooring system of a Wave Energy Converter is a challenging process that points out several unsolved technical problems, mostly related to the highly non-linear hydrodynamic phenomena occurring when high waves (e.g. 8 m high with 200 m wavelength) propagate in relatively shallow waters (e.g. 20 m). The aim of this note is to point out the relevance of the non-linear response of a WEC anchored in relatively shallow waters (shallow in the "non-linear" sense) in terms of loads applied to the mooring lines. Further, the effects of this cyclic load on the anchors is investigated. Note that to some extent it is like checking the importance of geotechnical and coastal engineers in the design process of the WEC structure and its mooring system (typically carried out by naval architects). The whole mooring design process is first outlined and then it is schematically applied to a specific case, namely a promising Italian device named SeaBreath (www.seabreath.it), in view of a possible deployment in the Adriatic Sea. The main concern of mooring designers is related to resonance effects induced by the second order drift. Therefore specific tests have been carried out in the 36 m long × 1.0 m wide × 1.3 m high wave flume of Padova University. Tests focused on the forces on the mooring lines induced by the sum of two regular waves of similar frequency. The mooring design is still far from complete: the physical model proved the relevance of the aforementioned effects but a numerical investigation (not yet performed) is required to draw final conclusions.
The system of timber palisade groins can be very helpful as a measure coexisting with artificial nourishment and increasing the lifetime of beach fills. To this end, good condition of groins and their permanent contact with land is necessary. On the basis of theoretical modelling and field surveys a conclusion has been formulated that coexistence of complete groins with artificial shore nourishment causes that about 30% less sediment is washed away from the nearshore zone than for beach fill without groins.
This note presents the Seabreath wave energy converter, basically a multi-chamber floating oscillating water column device, and the lumped model used to size its chambers, the ducts and the turbine. The model is based on extensive testing carried out in the wave flume of the University of Padova using fixed and floating models with a dummy power take off and indirect measurement of the produced power. A map with the available energy in the Mediterranean Sea is also proposed, showing possible ideal application sites. The Seabreath is finally dimensioned for a quarter scale test application in the Adriatic Sea, with a 3 kW turbine, and a capacity factor of 40%. © 2013 by the authors.
Risk is a popular topic in many sciences - in natural, medical, statistical, engineering, social, economic and legal disciplines. Yet, no single discipline can grasp the full meaning of risk. Investigating risk requires a multidisciplinary approach. The authors, coming from two very different disciplinary traditions, meet this challenge by building bridges between the engineering, the statistical and the social science perspectives. The book provides a comprehensive, accessible and concise guide to risk assessment, management and governance. It includes formal approaches to risk analysis without assuming a high level of mathematical proficiency but it also offers reflection and deliberation about the socio-political context in which risk issues are embedded. A basic pillar for the book is the risk governance framework proposed by the International Risk Governance Council (IRGC). This framework offers a comprehensive means of integrating risk identification, assessment, management and communication. The authors develop and explain new insights and add substance to the various elements of the framework. The theoretical analysis is illustrated by several examples from different areas of applications.
Preface. Introduction. Contributors. The0dock-in-service: evaluation of load carrying capacity, repair, rehabilitation. Marine structures in cold regions. Shiplifts, marine railways, shipways, and dry (graving) docks. Offshore moorings. Floating breakwaters. Marinas. Bridge pier protection from ship impact. Index.
This paper reviews the common theories for determining the magnitude and distribution of wave forces on vertical walls and sloping, rubble-mound breakwaters and compares these theories, selecting the best available for use. The results of the better theories are compared with experimental data, and an outline is given of experimental investigations considered necessary to obtain data sufficient for the design of economical and safe breakwaters.
Extreme sea level events are a current global threat, whilst sea-level rise (SLR) and climate change over the 21st century will increase the frequency and severity of flooding in most coastal regions. Numerical model simulations can help to understand and predict coastal floods (e.g. flood mapping and forecasting) but in comparison to flood sources (waves and water levels) coastal flood pathways (defence failures and inundation) are presently less integrated within these models. This thesis develops and demonstrates a methodology to rapidly simulate and understand the consequences of coastal flood events, with an emphasis upon regions where the risks of flooding are not well understood and could change quickly with SLR. The Solent on the south coast of England is the case study, and is prone to frequent flooding. This region is currently differentiated from the UK east and west coasts by experiencing smaller storm surges, and is characterised by undefended sections of shoreline and small floodplains. Within the Solent is Portsmouth, a city of national flood significance (only London and Hull contain more people considered at risk of coastal flooding in the UK). However, life threatening floods have not occurred in living memory. An integrated modelling approach is developed, coupling loads and defence failures with two-dimensional simulations of floodplain inundation. Observations collated from a real storm surge and flood event are shown to generate a validation data set, which indicates that this model can predict floodplain water levels to a good level of accuracy, whilst highlighting implications of such data collection. Solent-wide analysis includes simulations of hypothetical coastal flood events based upon scenarios that cover the full range of coastal loadings (realistic waves and water levels) and defence failures (overflow, outflanking, overtopping and breaching). More detailed case-studies are also applied at two sites within the region (including Portsmouth). This analysis generates peak flood water depths and an overview of impacts across this spectrum of possible floods.
This research improves the existing knowledge of coastal flooding in the case study, and highlights a number of generic concepts that should be applied to others. For example the combination of flood simulation methods with real flood event analysis is essential for optimising the interpretation of model outputs whilst supporting inferences about flood consequences associated with extreme loading events (including how these may change with SLR). Simple methods estimated that >24,000 properties are within a 1 in 200 year flood event outline; and incorporating defence failures, flood dynamics, validation and detailed case studies substantially refine the assessment of places likely to experience damages. Breach defence failures generate the worst flood impacts, although in the Solent this failure mechanism is presently less of a threat than outflanking, overflow and wave overtopping. The modelling system includes easily interpreted outputs, whilst being computationally fast; therefore with potential applications including supporting land-use and defence planning, and real-time flood forecasting and warning.
The water-air two-phase flow model based on multi-phase flow theory for describing the leakage of air flowing into the clay interlayer via a fracture in the operation process of air-cushioned surge chamber is established. The amounts of air losses for different ratios of pore water pressure in rock mass to compressed air pressure in surge chamber are calculated. It is found that the air losses decrease quickly when the ratio increases, which indicates that the water curtain for preventing the air leakage is effective. In consideration of the effect of geological conditions, the pressure of water curtain, air pressure in surge chamber and properties of rock mass are taken into account. The proposed two-phase flow model can be used to assess the air losses, design of water curtain and provides the basis for remediation of the leakage of air-cushioned surgechamber.
The formation of a dredged hole off an open coast can induce the loss of sand due to the deposition of the littoral drift into the hole, or the shoreline changes through the longshore changes of wave height and wave angle. The present study investigates the conditions of the dredging of the offshore bed on the Kochi Coast, facing Tosa Bay. Aerial photographs and the sounding data of the coast are analysed to obtain the beach changes accompanied with the formation of the dredged hole. The hole was refilled slowly from the west side by the littoral drift directing eastward. Abrupt change of the topography due to the onshore-offshore sand transport did not happen, although the slope of the hole was very steep. Furthermore, it is found that the shoreline behind the hole dredged in a depth shallower than the critical depth for sand movement tends to retreat in the temporal and spatial meaning. This is also confirmed by the theoretical analysis. In addition to the results, it is concluded that the characteristic height of beach changes due to littoral drift is equal to 7.5 m on the coast, and that the transport rate trapped by Katsurahama Breakwater of Kochi Port, located east end of the investigated region, is around 6000 m³/yr, averaging over a period between 1947 and 1983.
The efforts to save environment from acid mine drainage (AMD) were discussed. The Queensland government has established two trial soil covers and a trial revegetation plot to rehabilitate the Mount Morgan mine. The consulting team has designed and constructed two cover types in the trial area.
This book highlights the technical advances in the field of dikes and revetments based primarily on research and practice in the Netherlands. The content of the book provides a comprehensive overview of the main practical matters related to the design and maintenance of dikes and revetments. The contributions have been prepared by the Dutch experts participating in the study groups of the Technical Advisory Committee on Water Defences. The content of this book is structured in such a way that, after an introduction and history, it opens with an outlines of general strategy and methodology on sea defences, illustrated in the following chapters by technical information on specific items and Dutch experience, and it ends with more general aspects such as probabilistic approach, integral (multifunctional) design, management and safety assessment. All chapters together provide an almost complete technical overview of the items needed for the design and maintenance of dikes and revetments. Moreover, the enclosed CRESS-program allows one to make a first estimation of hydraulic loads and preliminary design. This book is intended for authorities and persons responsible for the planning, design and assessment of measures for the protection and maintenance of coastal areas.
Full-scale tests were conducted in the Colorado State University Wave Overtopping Test Facility to evaluate the wave overtopping resiliency of grass-only slopes and grass slopes strengthened with turf reinforcement mats (TRMs). The soil underlying the grass was either stiff clay or soil with a high percentage of sand. The purpose of these tests was to develop design information needed by the U.S. Army Corps of Engineers' New Orleans and Jacksonville Districts. Well-maintained grass with healthy root systems is capable of resisting substantial unsteady wave overtopping loads characterized by high instantaneous flow velocities and very energetic turbulence. Grass nurtured on stiff clay was more resilient than grass on sandy soils, and turf reinforcement mats could withstand wave overtopping hydraulic loading several times greater than grassonly slopes.
The effect of manmade activities is primarily local but can extend far away from the location of intervention. This underlines the importance of establishing coastal zone management plans covering large stretches of coastlines. In recent years, interest in Low Crested Structures (coastal defence structures with a low-crest) has been growing together with awareness of the sensitivity to environmental impacts produced by coastal defences. The relation between wave climate, beach erosion, beach defence means, habitat changes and beach value, which clearly exists based on EC research results, suggests the necessity of an integrated approach when designing coastal protection schemes. In accordance with this need, the present design guidelines cover structure stability and construction problems, hydro and morphodynamic effects, environmental effects (colonisation of the structure and water quality), societal and economic impacts (recreational benefits, swimming safety, beach quality). Environmental Design Guidelines for Low Crested Structuresis specifically dedicated to Low Crested Structures, and provides methodological tools both for the engineering design of structures and for the prediction of performance and environmental impacts of such structures. A briefing of current best practice for local and national planning authorities, statutory agencies and other stakeholders in the coastal zone is also covered. Presented in a generic way, this book is appropriate throughout the European Union, taking into account current European Commission policy and directives for the promotion of sustainable development and integrated coastal zone management. * Shows the reader how to perform an integrated design of coastal defence schemes * Presents latest insights on hydro-morphodynamics induced by structures * Provides directly applicable tools for the design of low crested structures * Highlights socio-economic perspectives in coastal defence design.
On coasts with high tidal ranges, or subject to high surges, both still water levels and waves can be important in assessing flood risk; their relative importance depends on location and on the type of sea defence. The simultaneous occurence of large waves and a high still water level is therefore important in estimating their combined effect on sea defences. Wave period can also be important in assessing run-up and overtopping, and so it is useful also to have information on the joint distribution of wave height and period. Unless the variables are either completely independent or completely dependent, multivariate extremes are difficult to predict directly from observational data, as there may be too few events of the relevant type amongst the observations. In the past, the fitting and extrapolation of the dependence functions between the variables has often involved complicated and/or subjective approaches. This paper presents a method for joint probability analysis, using a Monte Carlo simulation approach, based on distributions fitted to water level, wave height and wave steepness, and to the dependence between them.
Water power absorption by a system of interacting bodies is analysed within linear thoery. A general expression for the wave power absorWed by the system, in terms of far-field velocity potentials, is derived. The optimum power absorption by a system of identical bodies from a plane incident wave is obtained. The theory is applied to various configurations of bodies oscillating in one or two modes. It is shown that the interaction between properly spaced bodies may raise the absorbed power per body by a substantial factor. It is also demonstrated that a single row of oscillating bodies may absorb 50 percent of the incident power if the bodies are operated in one mode and 100 percent if operated in two modes. (A)
IPCC projections indicate that the rate of sea level rise (SLR) during the 21st century may be about an order of magnitude greater than the 20th century rate of 1–2 mm/year. This accelerated SLR will in turn result in much faster coastline retreat with particularly severe impacts on low–lying areas. The socioeconomic impact of such accelerated coastline retreat could be massive due to the rapid growth of coastal communities and infrastructure over the past five or six decades. The method most commonly used to estimate coastline retreat due to SLR is the simple two-dimensional mass conservation principle known as the Bruun rule. However, in view of the high level of predictive accuracy that is clearly needed to facilitate informed planning decisions for the future, can we continue to depend on the Bruun rule? This chapter discusses the evidence for and against the Bruun rule and suggests alternative methods that may be more suitable for the 21st century. © 2010 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
'Risk Governance is a tour de force. Every risk manager, every risk analyst, every risk researcher must read this book - it is the demarcation point for all further advances in risk policy and risk research. Renn provides authoritative guidance on how to manage risks based on a definitive synthesis of the research literature. The skill with which he builds practical recommendations from solid science is unprecedented.' Thomas Dietz, Director, Environmental Science and Policy Program, Michigan State University, USA "A masterpiece of new knowledge and wisdom with illustrative examples of tested applications to realworld cases. The book is recommendable also to interested students in different disciplines as a timely textbook on 'risk beyond risk'." Norio Okada, Full Professor and Director at the Disaster Prevention Research Institute (DPRI), Kyoto University, Japan 'There are classic environmental works such as The Tragedy of the Commons by Hardin, Risk Society by Beck, The Theory of Communicative Action by Habermas, and the seminal volumes by Ostrom on governing the commons. Renn's book fits right into this series of important milestones of environmental studies.' Jochen Jaeger, Professor at Concordia University, Montreal, Canada 'Risk Governance provides a valuable survey of the whole field of risk and demonstrates how scientific, economic, political and civil society actors can participate in inclusive risk governance.' Jobst Conrad, Senior Scientist, Social Science Research Center Berlin, Germany 'Renn offers a remarkably fair-minded and systematic approach to bringing together the diverse fields that have something to say about 'risk'. Risk Governance moves us along the path from the noisy, formative stage of thinking about risk to one with a stronger empirical, theoretical, and analytical foundation.' Baruch Fischhoff, PhD, Howard Heinz University Professor, Carnegie Mellon University, Pittsburgh, USA 'I cannot describe how impressed I am at the breadth and coherence of Renn's career's work! Written with remarkable clarity and minimal technical jargon… [this] should be required reading in risk courses!' John Graham, former director of the Harvard Risk Center and former deputy director of the Office of Budget and Management of the Unites States Administration This book, for the first time, brings together and updates the groundbreaking work of renowned risk theorist and researcher Ortwin Renn, integrating the major disciplinary concepts of risk in the social, engineering and natural sciences. The book opens with the context of risk handling before flowing through the core topics of assessment, evaluation, perception, management and communication, culminating in a look at the transition from risk management to risk governance and a glimpse at a new understanding of risk in (post)modern societies.
In this paper we present a methodology to estimate the probability of future coastal flooding given uncertainty over possible sea level rise. We take as an example the range of sea level rise magnitudes for 2100 contained in the IPCC Third Assessment Report [Church. J.A., Gregory, J.M., Huybrechts. P., Kuhn, M.. Lambeck, K., Nhuan. M.T., Qin, D., Woodworth, P.L, Anisimov, O.A., Bryan, F.O., Cazenave. A., Dixon, K.W., Fitzharris, B.B., Flato. G.M., Ganopolski, A., Gornitz. V., Lowe, J.A., Noda, A., Oberhuber, J.M., O'Farrell, S.P., Ohmura, A., Oppenheimer, M., Peltier, W.R., Roper, S.C.B., Ritz, C., Russell, G.L., Schlosser, E., Shum, C.K., Stocker, T.F., Stouffer, R.J.. van de Wal, R.S.W., Voss, R., Wiebe, E.C., Wild, M., Wingham, D.J. and Zwally, H.J., 2001. Changes in sea level. In Houghton, J.T. et al. (eds), Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom, 881 pp.] and infer a plausible probability distribution for this range. We then use a Monte Carlo procedure to sample from this distribution and use the resulting values as an additional boundary forcing for a two-dimensional model of coastal inundation used to simulate a 1 in 200 year extreme water level event. This yields an ensemble of simulations for an event of this magnitude occurring in 2100, where each member represents a different possible scenario of sea level rise by this time. We then develop a methodology to approximate the probability of flooding in each model grid cell over the ensemble and by combining these hazards maps with maps of land use values (consequence) we are able to estimate spatial contributions to flood risk that can aid planning and investment decisions. The method is then applied to a 32 km section of the UK coast in Somerset, South-West England and used to estimate the monetary losses and risk due a 1 in 200 year recurrence interval event under: (a) current conditions; (b) with the IPCC's most plausible value for sea level rise by 2100 (0.48 m) and (c) using the above methodology to fully account for uncertainty over possible sea level rise. The analysis shows that undertaking a risk assessment using the most plausible sea level rise value may significantly underestimate monetary losses as it fails to account for the impact of low probability, high consequence events. The developed method provides an objective basis for decisions regarding future defence spending and can be easily extended to consider other sources of uncertainty such as changing event frequency-magnitude distribution, changing storm surge conditions or model structural uncertainty, either singly or in combination as joint probabilities.
Coastal areas are vital economic hubs already affected by erosion, flood risk and long-term habitat deterioration. The growth of economy coupled with the acceleration of climate change draws the attention to sustainable coastal defence plans. Near-shore floating wave energy converters may be an innovative way to defend the coast with low environmental and aesthetic impact together with the secondary benefit of energy production. This contribution specifically addresses the use of devices of the Wave Activated Body type for coastal protection, based on 3D laboratory results. New experiments were carried out on a single device in 1:30 scale and on three devices of the same type in 1:60 scale in the deep-water wave tank at Aalborg University. Wave transmission, wave reflection, mutual interaction among the devices and device efficiency are assessed under a variety of conditions by changing wave steepness and water depth. Experiments allow a first outline of design guidelines for these kinds of combined installation for wave energy production and coastal defence.
A simple, robust, and general formula for the settling velocity of a particle is presented, taking into account the shape and roundness of the particles. It is based on the two asymptotic behaviors of the drag coefficient for low and high Reynolds numbers, respectively. The three coefficients in the proposed equation were fitted for different shape and roundness using explicit relationships. The proposed relationship yields the best results among the studied formulas for many kind of particles with various sizes, shapes, roundnesses, and densities. This formula could therefore be applied to any particle.
More frequent more intense storms predicted by climate models for the Pacific Northwest of North America could increase the regional landslide hazard. The impacts of one such storm are examined on Vancouver Island, British Columbia, during which 626 mapped landslides occurred, encompassing >5 km2 total area and generating >1.5 × 106 m3 of sediment. The relationship between rainfall intensity, air temperature and wind speed obtained from mesoscale numerical weather modelling is examined relative to landslide incidence within steep terrain. A critical onset of rainfall intensity between 80 and 100 mm in 24 h that results in a rapid increase in landslides with increasing precipitation is demonstrated. The argument is presented that this result is more useful for landslide management decisions than a minimum threshold. The component of wind-driven rain was calculated, and results indicated that wind caused increased concentrations of rainfall associated with the occurrence of landslides. Approximately half the landslides studied were not related to rainfall alone, but to rain on snow, and we argue that wind played a crucial role. This often neglected component of hydrological analysis remains a major challenge as the role of snow transition zones and a warming climate in coastal mountain watersheds is considered.
