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Journal of Geography and Regional Planning Vol. 4(7), pp. 392-400, July, 2011
Available online at http://www.academicjournals.org/JGRP
ISSN 2070-1845 ©2011 Academic Journals
Full Length Research Paper
Municipal water supply planning in Oyo metropolis,
Oyo State, South Western Nigeria
Ufoegbune G. C.*, Oparinde O. C. and Eruola A. O.
Department of Water Resources Management and Agrometeorology, University of Agriculture, Abeokuta, Nigeria.
Accepted 10 May, 2011
The study attempted a municipal water supply planning in Oyo metropolis using a land based approach
to prepare a long range forecast of water supply demand for Oyo metropolis with the aim of providing
effective planning, development and operation of water supply and distribution networks which is one
of the most essential compounds of urban infrastructure. The problem of water sector in Oyo
metropolis was reviewed and the challenges which may result from the capacities of the facilities of the
provision in Oyo metropolis was taken care of through the designs of facilities that will ensure
adequate planning for, till the projected year. The study delineated the areas within the metropolis that
are unserved or underserved by the water corporation. Geographic information system (GIS) was
applied to existing distribution maps of the water corporation to present a graphic detail of the current
state of facilities frame work for taking management of new facilities was given. Large scale facility
maps that will serve as source of information for vital application for the Erelu water corporation in
carrying out its daily function were produced. Such maps in digital forms are extremely vital and are
useful to integrate collateral data, that is, available within the corporation.
Key words: Water supply, Oyo metropolis, Geographic Information System (GIS).
INTRODUCTION
The socio-economic life of man can never be completed
in the absence of water; as a result of this, man has been
struggling to make sure water is never out of his reach.
As population increases, more pressure will be put on the
available water resources. So, many methods are
adopted by man to analyse the problems of water supply
in order to have water within his reach by conservation
and storage of rain water in some areas for their daily
activities (Ajibade, 2005; Chaudhery, 2005; Ufoegbune,
2009).
With man’s persistence in the search for continuous
availability of water, many land-owners in Oyo metropolis
had to dig wells around them (Ayoade, 1988). 3.46% of
the total population in the metropolis according to Census
(2006) data depend on well water for all activities, 8.06
and 1.25% depend on inside pipe-borne and outside
pipe-borne water respectively; 5.11% depend on
tanker/vendor supply, 2.37% depend on borehole, 8.99%
on rainwater, 19.8% on nearby rivers, 1.14% on dam and
3.79% of the people on other sources like subsurface
*Corresponding author. E-mail: gidufoes2000@yahoo.co.uk
water as springs.
The plan of water supply in Oyo town has become
ineffective because fewer numbers of people in Oyo
metropolis have access to water supply (Oyebande,
2005). So, there is need for proper planning which
entails: Proper abstraction, treatment and distribution in
the right amount needed.
The objective of this study is to provide effective
planning needed for the supply of potable water across
all parts or areas of the metropolis.
Oyo town is located in the North of Ibadan, the capital
city of Oyo State situated in the south western part of
Nigeria and lies between latitude 7º.8'33"N and 7º.9'33"N
and longitude 3º.8'67"E and 4º.0'00"E. The state, Oyo,
was reduced in size when Osun State was created out of
its eastern portion in 1991. Oyo is bounded by the states
of Kwara on the north, Osun on the east, and Ogun on
the south and by the Republic Of Benin on the west
(Figure 1). Oyo State is traversed by the Yoruba hills in
the north. The state has some tropical rain-forest in the
south around Ibadan, the state capital, but the remaining
parts of the state are covered by Derived Savanah
(Ayoade, 1983).
Erelu Dam is one of the dams built by Water Corporation
Ufoegbune et al. 393
Figure 1. Map of Nigeria showing Oyo State and Oyo town.
of Oyo State. The dam was built in Oyo town in 1961 on
Awon River along Oyo/Iseyin to supply potable water to
the town and its environs. The water scheme was
commissioned in 1963.
The impoundment area of the dam is 161.07 ha, and
the catchment area is 243.36 km. Erelu dam is about 6.4
km from the heart of Oyo town. Oyo town is located in the
North of Ibadan, the capital city of Oyo State. This
appears to be the major source of water supply to Oyo
and its environs Figure 2.
The water scheme treatment plant is a conventional
type with an output of 7.5 million liters per day and
reservoir capacity of 10 cm3. The project was set up
when the population of Oyo was 112,349.
Materials used for the study included map of existing
facilities of the metropolis, showing distribution pipelines,
pumping station, future and present population statistics
of the area, information on WHO and other standards for
daily water requirement per person per day and GIS
software (Arcview 3.2a with spatial analyst extension).
Water demand forecast are usually based on
population which requires accurate population forecasts.
For the purpose of this project, a growth rate of 2.5%
shall be adopted for Oyo. The compound growth rate is
given as:
where Pn = projected population for nth year, P0 = initial
population figure = 2006 NPC Figure (428,798), r =
growth rate = 2.5%, n = numbers of years from 2006,
P2010 = 428,798 (1+ 2.5/100)4, P2015 = 428,798 (1 +
2.5/100)9, P2020 = 428,798 (1 + 2.5/100)14, P2025 =
428,798 (1+ 2.5/100)19, P2030 = 428,798 (1+ 2.95/100)24.
The consumption was given as a product of population,
per capita consumptions of 160 L/day and a safety factor
of 1.6.
Design of intake conduit was done assuming a
maximum daily demand of 2.585 m3/s and a self
cleansing velocity of 1.8 m/s adopting:
where Q = pipe discharge / intake (m3/s); V = velocity of
flow (m/s), and A = cross sectional area of pipe (m2)
A =
=
where A = cross sectional area of pipe (m2), and d =
diameter of pipe (m).
394 J. Geogr. Reg. Plann.
Figure 2. Oyo showing local government areas.
For the purpose of this study, two intake pipes will be
adopted; each approximately 0.7 m in diameter. In the
selection of low lift pump, the following factors must be
taken into consideration. The factors are the average rate
of consumption, the requirement of the mixing tank, the
low water level in the reservoir, losses in the delivery and
suction and the total head.
According to Ajibade (2005), the effective head which
the pump must provide is equal to the total lift plus the
friction loss and as well as the kinetic energy of the fluid
at discharge.
In summary:
He = Hs + Hd + Hfs + Hds + V2d/2g
where, He = effective head which the pump must provide,
Hs = suction lift, Hd = delivery lift, Hfs = loss of head in the
suction pipe, Hds= loss of head in delivery pipe, V2d/2g =
velocity head in delivery pipe, Hs is a head factor highly
dependent on the water level / depth distance to the
pump in the low lift pump house, Hd is a factor of head;
that is water level in the treatment plant, Hf = Head loss in
pipe = (2.5 - 3.0), Hm = water losses in the pipe = (0.8 - 1
cm), Total head for pump H = Hs + Hd +Hf +Hm
For the purpose of this study, H is adopted and
stipulated at 30 m. The efficiency of centrifugal pump lies
between 0.40 and 0.85
If the pumping efficient is put at 75% putting discharge Q,
which is the maximum daily requirement at 2.585
m3/s>BHP =
For this purpose; selection of 2 stand-by pump of 7000
HP each is required.
Design of aerator was done with a detection time of 2
min and a depth of tank of 2 m
Note that: The quantity of water required = 115.11m3/min
The rectangular chamber spraying water will have the
capacity of length = 15 m, breath = 1 m
Therefore volume of aerator tank = 115.11 m3/min × 2
min
Making assumptions for two aerator tank, therefore
volume of 115.11 m3,
Surface area = v/d =
The cross-sectional area of rectangular chamber
spraying water = L × B
Therefore, total surface area required for one (1) aerator
tank will be (57.55 + 15) m2 and adopted surface area of
16.5 m length and 4.5 m breadth.
METHODOLOGY
Design of solution tank
Aluminum compound shall be used as t he coagulant for flocculation
process in this project. The dosing for turbidity ranges from 70 to
120 ppm according to Barnes et al. (1981).
90 ppm shall be adopted for this study.
Consumption = 160 l.c.d
Maximum daily consumption = 186,138.7 m3/day
Dosing for turbidity = 90 ppm
Maximum weight of coagulant used daily (20 h)
= 90 (gm/m3) × 186,138.7 (m3/day)
= 16,752,483 gm/day
= 16,752 kg
If the coagulation will be used in form of solution with 20%.
Therefore volume required =
Volume of tank approximately = 85 m3
Discharge of solution =
Design of flash mixer
Assume the detention period of 2 min, maximum water demand of
115.11 m3/min, volume of flash mixer of water demand × 2 min
given 115.11m3/min × 2 min with an assumed depth of 1.5 m. This
will be as area divided by 1.5 m and gives 230.22 m3
Design of a clarriflocculator
Assume detention time of 40 min
Assume the depth of 5 m
Quantity of water required = 115.11 m3/min
Volume = (115.11 × 40) (m3/min × min)
Assuming 4 units of the tank
Volume of one (1) unit =
Area = =
Area =
d2 =
Let the diameter of the flocculation = 17.12 m
Design of clarifier (settling tank)
Detention time = 4 h
Depth of tank = 6 m
According to Barnes et al. (1981), depth of sedimentation tank is
usually 0.6 to 1.2 m more than flocculation tank.
Ufoegbune et al. 395
Quantity of water required = 9306.94 m3/h Volume required =
(9306.94 × 4) m3
Assume units of this tank are 8 (eight)
Volume of 1 unit =
Surface area =
For circular shape type clarifier
Area =
To optimize the use of land area flocculation unit is usually
constructed in the middle of the clarifier.
Volume of the tanks unit each = 4518.47 m3 + 1151.1 m3
Assume a depth of 6 m for the unit
Therefore surface area =
Therefore adopted diameter for clarriflocculator unit = 35 m
Design of filter tank
Operation rate according to Helthes et al. (1986) slow filter are
usually designed for normal operation at a rate of 0.1 m3/m2/h.
However, a pilot studies have shown that higher rates of 0.2
m3/m2/h or even 0.3 m3/m2/h may be used without deterioration to
fill water quantity.
Quantity of water required = 9306.94 m3/h
Assume operation rate = 0.3 m3/m2/h
Total filter bed area =
Assume 20 units of this;
Adopt size 45 × 35 m
If the depth of filter bed = 0.7 m
If the depth of sub grade = 0.85 m
Assume freeboard = 0.4 m
Depth of under rain = 0.5 m
Total depth = 4.45m ≈ 4.5 m
Design of clear water tank
Maximum daily consumption = 9306.94 m3/h
Detention period = 4 h
Total volume of tank = (9306.94 × 4)m3
For easy management select 4 number of tanks
Volume of 1 tank =
396 J. Geogr. Reg. Plann.
Assume the depth of tank = 8 m
Surface area =
Adopt size of 30 m (breadth), 40 m (length) and 8 m (depth)
Transmission works
Design of high lift pump
According to Ajibade (2005), the break horse power (BHP) of the
high lift pump to be used is very important. It will be recommended.
Assume a total head (H) = 80 m
Maximum water requirement Q = 2.585 m3/s
Pumping efficiency = 75%
Efficiency of pump = 0.75
Pumping is usually done in two shifts in a day 24 h, that is, morning
and evening.
BHP =
=
Design of rinsing main
Rinsing main conveys water from c lear water tank to service
reservoir.
Take velocity = 1.5 m/s
Maximum water requirement = 2.585 m3/s
Area =
Design of service reservoir
The service reservoir is normally designed to st ore 20 to 50% of
maximum daily water.
Maximum hourly demand of water for projected population for the
year 2030
Projected population = 775,578.5
Recommended per capital per day = 160 L
Recommended factor of safety = 1.5
Maximum daily consumption = 775,578.5 ×160 × 1.5
Maximum hourly demand per hour
m3/s
Maximum daily demand = 7754.4 × 24
If 50% of maximum daily demand is allowed for capacity volume
require = 93,052.8 m3.
Making use of 12 reservoirs well spread all over the city.
Capacity of one reservoir = 7754.33 m
If the depth of tank = 10 m
Surface area =
For circular tank Area =
Therefore use 12 numbers 32 m diameter, 10 m depth circular
reservoir each.
Design of gravity mains
Maximum water consumption = 2.585 m3/s
Assuming flow velocity in pipe = 2 m/s
A =
Area =
Distribution works
In water supply system, water is tr ansported under pressure
through a distribution network of buried pipes. Smaller pipes, called
house service lines, are attached to the main water lines to bring
water from the distribution network to houses. In water supply
systems, water pressure is provided by pumping water up into
storage tanks that store water at higher elevations than the houses
they s erve Figures 3 and 4. The force of gravity then "pushes" the
water into homes when tap is opened. A pump brings the water out
of the ground and into a small tank within the home, where the
water is stored under pressure.
Areas that are not properly served by potable water supply is
identified by superimposing of the existing pipeline distribution plan
on the topogr aphical map of the area (Oyo N. E.) which shows the
total area cover of the metropolis Figure 5.
RESULTS AND DISCUSSION
The projected population is given in Table 1.
The projected population of Oyo metropolis using
National Population Census (NPC) 2006 figure at 2.5%
growth, showed that population of the metropolis will
continue to increase immensely and provision of social
amenities to cater for the needs of the increasing popula-
tion must be planned to ensure availability throughout the
design period.
In planning for water sustainability and sufficiency,
maximum water per capital demand was generated to
determine the maximum amount of potable water to be
supplied by multiplying the projected population figure for
the year with recommended per capital per daily
consumption and with the recommended safety factor.
Results are shown in Table 2.
The results of the design of facilities will foster the
effectiveness of potable water supply in the metropolis
are shown in Tables 3 to 5.
Collection works include the intake conduit and the low
Ufoegbune et al. 397
Figure 4. Map showing elevation query.
Figure 5. Map showing the existing pipeline on the present land area over of the metropolis.
398 J. Geogr. Reg. Plann.
Table 1. Projected population.
Year Population projection
2010 473,312
2015 535,509
2020 605,878
2025 685,496
2030 775,577
Table 2. Water demand for the year 2010 and 2030.
Water demand Liters/day m
3
/h m
3
/min m
3
/s
2010 113,594,880 5680.08 94.67 1.577
2030 186,138,720 9306.94 115.11 2.585
Table 3. Showing collection works design.
Collection work Diameter of pipe Number
Intake conduit 1.35 2
Low-lift pump - 2
Table 4. Showing design parameters of purification works.
Purification/
Treatment work
Area
(m2)
Volume of
tank (m3)
Discharge
(l/s)
No of tank
needed
Depth
(m)
Diameter
(m)
Adopt size
(m)×(m)
Aerator 72.56 230.2 - - - - -
Solution tank - 85 1.180 - - - -
Flash mixer 153.48 230.22 - - - - -
Clarriflocculation - 115.11 - 4 - 17.12 -
Clarifier 753.07 4518.47 - 8 - 31 -
Filter tank 31,023 - 20 4.5 - 45 × 35
Clear water tank 1163.36 9306.94 - 4 - 30 ×40
Table 5. Showing transmission works.
Transmission work Diameter of
pipe (m)
Velocity
(m/s)
Number Volume
(m3)
Depth
(m)
Surface area
(m2)
High - lift pump - - 3 - - -
Rinsing main 0.74 1.5 2 - - -
Serviceable reservoir 32 12 7754.3 10 775.43
Gravity main - - - - - -
lift pump station that helps in abstraction of raw water
from the dam. Result of water demand per person per
day gives consideration to the quantity of water that must
be abstracted to meet to meet the demand.
Table 3 shows the result of the design of the collection
works. Two intake conduit pipe of diameter 0.7 m must
be adopted and two stand-by pumps of 700 hp each is
required.
The result of the designed parameters of purification/
treatment works are shown in the Table 4 showing
different planning requirements for various facilities used
in the treatment work.
The result of the transmission works (Table 5) showed
that 3 high lift pumps of 1300 hp each will be required to
fit in with the requirements of water demand. Twelve
reservoirs are needed to cater for the needs of the
Ufoegbune et al. 399
Figure 6. The combination of the generated map.
metropolis within the design period of 20 years; reservoir
must be well allocated within the catchment area of Oyo
metropolis. 5 reservoirs must be allocated to Atiba Local
Government Area of the metropolis.
3 reservoirs allocated to Oyo East Local Government
Area of the metropolis and 4 reservoirs to Oyo west Local
Government Area of the metropolis. Since, Atiba Local
Government area has 39.23% population of the total
population of the metropolis, Oyo East has 28.94% and
Oyo West has 31.82%.
The elevation query of the map distinguished between
areas of elevation below 300 m and elevation at 300 m
and above. Areas of 300 m elevation and above are
areas suggested for the citing of reservoirs that will
ensure proper distribution of potable water with or without
being incorporated by a booster station, with the use of
sluice valves that helps in diversion. The points are the
red dot box on the map so reservoirs can be distributed
as designed for the metropolis based on population
density of the area.
Figure 5 shows the facilities of existing facilities of the
Erelu water corporation. There is need for the pipe
network to cover all areas more effectively for new
development areas to be adequately catered for. The
plan of the existing facilities of the water corporation
include one reservoir of 900,000 gallons/ 4091.4m3
capacity located at Sooro Hill (Figure 6) and some
pressure control valves along the pipeline that allows
maximum diversion of water from cannot meet the
demand and requirement of the metropolis.
Conclusion
To satisfy the water requirement of the people of Oyo for
domestic and other uses from 2010 to 2030, the
expansion of the dam must be made to impound water at
its maximum capacity that will ensure regular abstraction
to meet peoples demand after undergoing the required
treatment units. This situation agrees with the previous
work done in Abeokuta Metropolis (Ufoegbune et al.,
2009). The plan for municipal water supply made for Oyo
town will far outweigh the present works in the city. Since,
Oyo a large town has suffered shortage of potable water
in the last two decades. Though the ancient town plays
host to four tertiary institutions and a federal government
girls’ college, it is still grappling with water scarcity. For
upward of 2 decades, residents have relied on the Erelu
water works for it supply of tap water through the capacity
of the dam is grossly inadequate for the increasing
population of the town. For a town consisting of mainly
civil servants, farmers and artisans; a borehole is largely
a luxury so there is need for the government to expand
the dam to be able to impound more water that can serve
the entire population adequately well both satisfactorily in
quality and quantity. It should also be noted that plans
are made on the ultimate water requirement, which is
year 2030 water requirement. Thus, plants may not be
used to its fullest capacity until year 2030. Extensions of
pipe lines need to be provided to cater for the water
requirement of the people both now and in future. The
citing of reservoirs on the generated highest contour
400 J. Geogr. Reg. Plann.
elevation must be well distributed and be selected in such
to fulfill its purpose. The scheme planned for in the
project, when adopted and executed will bring a worked
improvement in the standard of living of the people. More
time will be committed to human, nature and material
enhancing activities than water hunting. The general
level of sanitation, cleanliness, healthy living will thus,
rise (Warner, 1995).
REFERENCES
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western Nigeria. Unpublished BSc Thesis, Dept of W ater Resources
Management and Agrometeorology, University of Agriculture,
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Ayoade JO (1983). Introduction to Climatology for the Tropics, John
Wiley, Chinchester.
Ayoade JO (1988). Tropical Hydrology and Water Resources,
Macmilan, Nigeria.
Chaudhery K (2005), Wastewater Infrastructure Planning Using GIS;
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Oyebande L (2005). “W ater Resources” i0.n Adalemo, I. A. and Baba, J.
M. (editors) Nigeria: Giant in the Tropics. A Compendium. Gabumo
Puplishing Co. Ltd.
Ufoegbune GC, Ladipo-Ajayi O, Oyedepo J, Eruola A (2009). GIS
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Warner DB (1995). "Water Needs and Demands: Trends and
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