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Ife Research Publications in Geography 14(2016) 17 - 29

IFE RESEARH PUBLICATIONS IN GEOGRAPHY Volume 14, 2016 ISSN-0795-073X

A GIS-Based Assessment of Potable Water Network Distribution in Osogbo, Nigeria Matthew Olomolatan Ibitoye & Faruq Okende Department of Remote Sensing and Geoscience Information System, Federal University of Technology, Akure, Nigeria. E-mail: [email protected]

Abstract This study examined the spatial distribution of existing public water facilities within Osogbo municipality using Geographic Information System (GIS), GPS and Remote Sensing technology. This was with a view to generating baseline information for optimizing water supply and distribution systems in the city. Analogue water utility sketch map were scanned, geo-referenced, and digitized. Google Earth, Landsat 8 and ASTER GTM images of the study area, were used for various analysis in ArcGIS environment. Also, the land use land cover analysis was carried out to depict urban expansion that had taken place over the years in the study area. The analysis revealed that the city had areally expanded beyond the coverage of the existing pipeline networks having covered just 21.5 sq.km (32%) of the present municipal area (67.07 sq.km). This indicated that if all the facilities are working maximally, only 32% of the total area would have access to water supply. The study therefore concluded that public water supply distribution system in Osogbo was far below meeting the Millennium Development Goals (MDG) on potable water supply in the less developing country like Nigeria. The study suggested suitable site locations, based on the suitability analysis for siting of water reservoirs for optimal water distribution in the study area. Key words: Portable water, GIS, GPS, Land Use Land Cover, Networks distribution. Introduction Water is considered to play a very crucial role in human survival, and it is known to be one of the four major essentials of life; food, shelter, clothing and water (Denton, 1990). Apart from constituting the highest component of Human body, water plays indispensable role in hygiene and other activities of man. It therefore becomes one of the most basic needs of man. The socioeconomic 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. There are various means from where man traditionally source for water particularly in the tropical region. The sources range from rain water, surface (stream and brook), hand dug wells (Ajibade, 2005; Chaudhery, 2005; Ufoegbune, et al. 2009). As population increases and socio economic lives of the populace improve, there is more pressure put on the available water resources thereby making the supply of water in most communities or settlements inadequate particularly in the developing countries like Nigeria. The situation becomes worse during the dry season when there will

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be no rain to harvest, most well and stream dried up. Nigeria is endowed with about 267 billion cubic metres of surface water and about 52 billion cubic metres of groundwater, annually with the southern Nigeria recorded the highest source of water due to high rainfall and deep level of ground water aquifers in the zone (Ince et al., 2010). Despite the generous endowment of surface and groundwater, which are capable of meeting demands, only about 57% of the country have access to potable water (Ince, et al., 2010) with high (about 60%) concentration in the urban areas which require treatment plants, distribution systems, elevated tanks, piped systems, house connections, yard taps and public standpipes. The provision of potable water in adequate quantity and quality is a primary national and international concern across the globe. This was reflected in the Millennium Development Goals (MDGs) 7 target C where it was postulated that by 2015 not less than 86.6 percent of the world population would have adequate access to safe drinking water (NEDA, 2007).Barely one year after the target of 2015, the situation is far from attaining this objective particularly in Nigeria where lip service is only given to problem of potable water. There is no doubt, several efforts have been made by the government of Nigeria, through various agencies such as River Basin Development Authority at Federal level and Water Boards/Corporations at the State levels (World Bank Water Research Team, 1993; World Bank, 2011). For instance, about 550 million US dollar is injected into water sector annually (World Bank, 2015) and Governments both at State and Local Governments, even individual organizations, have been contributing to the supply of water to the people through its Public Service Infrastructure Policy (Lawal, 2003) by building reservoirs and sinking bore holes to supply potable water to the populace. Despite these efforts, supply of potable water in the country remain very scarce and far below the expectation of the MDG 7 target C

as most of the little efforts made were even concentrated in the urban centres. All the efforts put in place to guarantee effective and regular water supply in many of our cities particularly Osogbo, capital of Osun state, proved inefficient as a result of poor distribution system. Water sourced from the government is generally irregular or unreliable thus inadequate to meet the needs of the households (Adepoju, 2009). The Osun State government supplies potable water to Osogbo metropolis and forty other towns and villages in the 16 Local Government Areas of Osun State through the Ede Water Scheme (the largest water scheme in the state) built over thirty seven years ago (Adepoju, 2009). As at the time of this study, only few if any, parts of Osogbo, have access to potable water supply. A number of factors have been identified to have responsible for the inadequacies of water distribution system in developing countries like Nigeria. Some of these are identified as low water pressure, intermittent service and ageing of the infrastructure, thus resulting in the declining quality of water supply (WHO and UNICEF, 2000). Inadequate pressure is often inextricably linked to intermittent supply of water( Lee & Schuwab, 2005). This is by reducing pressure in the pipelines to reduce water supply to both the households and public stand pipes ( Kumar, 1998; Lee & Schuwab, 2005) Several published studies exist on water supply, water quality and water distribution in many parts of the world (e.g. Danilo, 2009, in Philippine; Elijamass & Abeaid, 2013, in Palestine; Olotuah, 2006; Afolami & Fadairo, 2014, in Nigeria,; Khadri & Chaitanya, 2014, in India). For instance, Afolami & Fadairo (2014) identified well and rain water, 36.4% and 34.83%, respectively as the main source of water supply to residents living around Federal University of Technology Akure (FUTA). In the core area of Akure town, Olotuah observed that 80% of the building in the core of Akure depend on hand dug wells for source of water supply , while 10% each relied on water from tanker services and public mains, respectively. Eljamassi & Abeaid (2013)

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focused their attention on the effective water distribution system in Gaza Strip in Palestine using GIS technique. So also was Ouiba (2011) in Ouagadougou, Burkina Faso and Khadri & Chaitanya (2014) in Jalgaon district, Maharashtra state, India. Audu and Ehiorobo, (2015) focused attention on mapping water distribution network in Warri Port Complex, Nigeria using geo spatial techniques to enhance economically and effectively water supply system in a medium sized town. As much as these research works contributed to the frontier of knowledge, much has not been reported as per water distribution system in Osogbo except the work of Fadare & Olawuni (2008) which focused on domestic water supply and health in residential area of Osogbo. Thus, this study was focused on potable water distribution system in Osogbo using Remote Sensing and Geographical Information System (GIS) techniques with the view of providing information for effective and optimal water distribution system. With GIS, it is possible to visualize, and model the entire cycle of water supply network from source to household (Khadri & Chaitanya, 2014; Ufoegbune et al., 2011). Among other capability of GIS, it enables user to store and display large amount of data graphically to greatly enhance the interpretation and analysis. In this regard, this study attempts to map out the network distribution pattern and to evaluate the demand and supply of potable water in Osogbo, Osun State, Nigeria Study Area Osogbo municipality in Southwestern Nigeria constitutes the study area. It is the capital city of Osun State and seat for both Olorunda and Osogbo Local Government Areas. The study area lies between latitude 70 44’ 45’’N and 70 48’ 30’’N and longitude 40 30’ 45’’E and 40 30’ 00’E with areal extent of about 67 Square Kilometers spread over average elevation of 320m above mean sea level and also characterized by humid tropical climate (Am and Aw of Koppen’s climate classification) with mean annual temperature of 220C and a mean annual rainfall ranging between 1.250mm and 1,400mm and distributed

between the months of March and October with peaks in July and September, and short dry spells in August (Adejuwon & Jeje, 1975). The area experiences the dry season between November and February due to the prevalence of the dust laden north-east trade winds (cT air masses) that blow across the region, loaded with fine dust from the Sahara desert with short periods of haze weather, locally referred to as harmattan (Odekunle, 1997). According to the 2006 National Population Census and Housing Commission Census, Osogbo has a population of 156,694 people. The population of this city has increased tremendously over the years, as a result of its role as the state capital and the seat for both Olorunda and Osogbo local government areas. Using the United Nation growth rate of 3.5%, Osogbo currently has an estimated population of 221,032 people. The development of Osogbo takes the pattern of other Yoruba traditional settlements characterized by old traditional core which is predominantly occupied by the native in groups of extended families. The core comprises of housing that are laid out in traditional compounds with many small rooms, limited open space with almost no access road to the buildings (Fadare & Olawuni, 2008). Outside the core area is the medium residential density areas that were mostly well laid out, with a regular street plan, almost completely occupied by two or threestorey buildings. The population in these areas is less homogeneous, consisting of people of diverse ethnic origins. The low residential density area (established as Government Residential Area) was consist typically of detached single family dwellings (Fadare & Olawuni, 2008). The supply of water in Osogbo is usually from four major sources; rainfall, pipe borne water, bore holes and hand dug wells. Pipe borne water is being supplied to Osogbo from both the old (constructed in 1952 by the government of old Western Region) and new (constructed in 1989 by old Oyo state) dams located on Erinle River near Ede. The old and new dams at their inception had storage of

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5,300,000m3 with the capacity of supplying 9 million litres per day (mld) and 94,000,000 cubic metres with the capacity of supplying 180 mld, respectively (Fadare & Olawuni, 2008, Osun State Water Corporation, 2015). However, the production levels of the two reservoirs; old and new, has dropped to 3.06 mld and 40.66 mld respectively (Fadare & Olawuni, 2008). This may be as a result of encroachment from other land uses such as built-up, agriculture and sedimentation of the reservoir (Adediji & Ajibade, 2008), thus, reducing the storage capacity of the reservoir. In addition, high presence of inorganic fertilizer, pesticides from farmland and untreated waste released into the river required further treatment before making the water suitable for drinking and inadequate funding may reduce quantity of water that will be treated and release for consumption per day (Oyebanji et al.,2012).

There are three ground level storage tanks in Osogbo municipal that serve as temporal water storage before distribution and they were located at Oke-Ayepe (old storage tank and has since been abandoned). The remaining two are located at Oke-Baale with 50, 610 cubic meters design capacity each and average delivery of 10,000 m3 (OSWC, 2015). Generally, the problems of water provision in Osogbo include inadequate supply and poor distribution system as the population of Osogbo keeps increasing without corresponding improvement of water supply mechanism.

Figure 1: Map of the Study Area (source: Google Earth image of Oshogbo).

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Materials and Methods Data Sources The data used for this study were collected from both secondary and primary sources. Data collected from secondary sources include analogue water utility map from the Osun State Water Corporation (OSWC) Osogbo, Google Earth Image covering Osogbo and its environs and Landsat 8 image (30m resolution) of the study area, acquired in 2014 for the preparation of land-use/landcover classification of the study area and ASTER GTM satellite (30m by 30m resolution) for generation of elevation map. The water utility maps which were in segment of A1 drawing sheets were photographed with digital camera (13 Megapixel) and later glued together as a mosaic sheet of water utility map for the study area. Location data (X,Y) obtained from the field using the GPS were imported with GIS software called Map source and converted to GPS exchange format and thereafter imported into ArcGIS environment for overlay. To clarify the existing water distribution system in Osogbo municipal area, ‘key informant interviews’ were conducted with Manger of the corporation, Engineer and water networks operators to ascertaining on the spot assessment of the functionality and problems encountered in ensuring an effective distribution of water supply in the study area. Data conversion The water utility maps of the study area which were in pieces were merged with the aid of CorelDraw X3 and converted to JPEG format in order to make the data importable into ArcGIS environment for further processes. ArcGIS 10.2 software was used to convert the scanned Water Utility Map (WUM) into vector entities by first georeferencing the map with coordinates of points taken from the field with the GPS. In other words, the image was registered to Universal Traverse Mercator (UTM)

Projection Coordinate System. ArcGIS software was preferred because it is embedded with image processing extension (tiff 6.0), a module used in viewing and processing image stored in (tiff) format. All the water distribution features on the map such as pipelines, valves, reservoirs, etc. were on screen digitized. A geodatabase file was created in ArcCatalog and the feature class (containing the features) was created. The pipes were represented as lines, the reservoirs as polygon while other features such as sluice valves, wash outs, water points, air valves, reducers etc. as points (see Figures 2 & 3). Data extraction On the Google image, online digitizing was carried out using polygon tool to get the area extent of Osogbo municipal which was in KML format. It was then converted and imported into ArcGIS environment using ArcGIS 10.2. The DEM used was acquired from ASTER GTM satellite with a resolution of 30m by 30m. Elevation Data was extracted from the DEM of the area using ArcGIS 10.2. The contour lines were labeled according to the elevation of the study area. Landsat 8 image (30m resolution) covering the study area, acquired in 2014 was used for the land-use/land-cover classification of the study area. Projected Water Demand Water demand forecast are usually based on population which requires accurate population forecasts. For the purpose of this project, the compound growth rate is given as: Pn = P0 (1+ )n …………(eq. 1) Where, Pn = projected population for nth year P0 = initial population figure=156,694 (NPC,2006) r = growth rate. United Nation’s population growth rate of 3.5% was adopted for the study. n = numbers of years from 2006 P2016 =156694(1 + 3.5/100)10 =221,032

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According to the World Health Organization (WHO), the optimal water consumption rate per person per day is given as 100 litres. Therefore, water demand in the study area (i.e. the total consumption rate of the population) is given as a product of population per capital consumption and safety factor of 1.5 For P2016 = 100 x 221, 032 x 1.5 = 33,154,800 L/C/D Overlay Analysis For optimizing the distribution of water supply, site suitability analysis of water reservoirs or storage tank location were carried out using spatial analyst tool of weighted overlay. The main criterion considered was the elevation where the reservoirs will be sited since water will always flow from high place downward. Also considered was the distance from built up areas that such a reservoir will serve. For the purpose of this study, the land use land cover classification map of the area was also performed to enhance effective sit selection for the reservoirs. Image classification For this study, supervised image classification using maximum likelihood approach was adopted. This classifier was used because of its effectiveness in land use and land cover classification that has been tested in many researches (Mullerova, 2005; Guo et al.,2008). The classifier makes use of mean and covariance which helps to narrow the class values to close to accurate and precise values. The classification algorithm was used in conjunction with a pixel based sample training technique on the image. This increased the separability of the classifier by distinctively identifying each land feature. Three land used types were identified for the purpose of this study; namely built up area, vegetation and water body. Site suitability of the reservoirs was considered using Weighted Overlay Analysis (WOA). The criteria utilized include, elevation and land-use. The ranking

of these criteria were given in Table 1. The ranking above was done on the basis that a reservoir should always be on the highest elevation and also be moved away from built/developed area. Results and Discussion The spatial distribution of existing facilities of Osun State Water Corporation in Osogbo in terms of existing reservoirs, reducers, water points, wash outs, sluice valves, air valves and utility pipes networks (Figure 2) and the extent of Osogbo municipal that the distribution system is to serve in Osogbo Metropolis is shown in Figure 3. It was obvious from the map that the distribution networks were concentrated to a small portion of the municipal, particularly Oke Fia, Isale Aro, Oja Oba, Oke Baale, Alekuwodo that constituted the core area of the settlement. The network covered about 21.5 sq.km (32%) of the total municipal area (67.07 sq.km). In view of the spatial distribution of the water supply network, it is evident that even if all the facilities are working maximally, only 32% of the total area will have access to water supply. Based on the interview conducted with the engineer and water works operators at Erinle, Dam and the storage points, water could only be pumped at the rate of 703m3/hour) with an average of 20 hours pumping per day as a result of unstable electricity supply to the water works. This occurrence was similar to the observation made by Thompson et al.(2000) in Iganga, Uganda where frequent power cuts led to the inoperability of water pumps resulting to unreliable water supply in the areas. Even the little water the waterworks was able to pump, reasonable quantities were wasted before getting to the consumers as a result of poor state of the water pipes which were as old as the scheme itself. The water pipes are ageing and not in good condition to support effective water supply as most of the water will be wasted due to pipe busting and leakages. The condition becomes worse as a result of

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damage during habilitation.

road

construction/

Even where the pipes were in good working conditions intermittent supply influenced the behaviour of those receiving the services as wastage occurred because taps were often left on to know when the water will run in the taps. This behavior was in accordance with the observation made by Kumar, (1998) in some cities in New Delhi, India where households left their taps on in attempt to draw maximum quantity of water during supply hours and thus, led to wastage. Putting all these problems together, the Engineer confirmed that the corporation could only deliver on the average of 10, 000m3/day (10, 000, 000 litres/day) from the two dams (Old and New Erinle), a value which is far below the daily need of 33,154,800 L/C/D for the population in the metropolis in 2016. Also the value was far below the design delivery capacity of 180, 000, 000 litres/day for the dams and 50, 610, 000 litres/day for the underground storage at Oke baale. It can be therefore be concluded that water supply in Osogbo are intermittent. Ordinarily, this pattern of water supply should be experienced during dry season when there is water shortage but it has becoming a norm rather than exception in the study area. In other words, water is supplied at specific time intervals not continuously and most at times the distribution cycle is completed every 72 and 120 hour. This is in agreement with Kelkar et al. (2002)’s in the city of Panaji, India where water supply was received for 3hours in the morning and 2 hours in the evening. This method was also adopted in Makkah, Saudi Arabia where water was pumped on regional basis for certain number of days and then rotate to another zone (Al-Ghamdi & Cutub (2002). This situation, further confirmed that water supply in Osogbo was very epileptic.

The land use land cover classification map (Figure 4) shows that three classes of land use namely; vegetation, built up and water body with the built up land use predominated the entire metropolis. This land use pattern further confirms that more areas such as Onward and Owode to the south and Oroki Estate to the north are built up areas that sprang up after the establishment of the water scheme in 1952. They are areas converted to built up land use outside the present coverage of pipe networks (which are kilometers away) from the source of potable water supply in the study area. Optimizing of the supply is a good way to meet the demand of the populace. In carrying out the optimization of the supply, building of more reservoirs in strategic locations is very essential. The site suitability map constructed for possible reservoirs locations show that area suitable (highest point) were identified at the southern part of the study area ( see Figures 5 and 6). The ranking criteria used for the suitability map was shown in Table 1. The ranking was done on the basis that a reservoir should always be on the highest elevation for easy flow of water following the theory of gravity. From this suitability map, it can be seen that the suitable sites proposed for placing of reservoirs are on the highest elevation located between Oke Baale and Owode as shown in Figure 6 and also they are located away from built up areas as shown in Figure 5. The elevation (332 -374m) for the proposed site for reservoir will not only guarantee sufficient (positive) pressure throughout the entire network but it will also enhance efficient water distribution across the whole municipality. Consequently, it will reduce the number and the cost of booster stations as of the case in the present distribution system.

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Figure 2: Digitized Water Distribution Network of Osogbo Municipal

Figure 3: Osogbo distribution water network and the areal extent of the municipality Ibitoye and Okende / Ife Research Publications in Geography 14(2016) 17– 29

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Figure 4: Land- use land-cover classification of the study area Table 1: Ranking of criteria CRITERIA

RANGE/LULC TYPES

RANKING

Elevation

255 - 295

1

295 - 334 334 - 374 VEGETATION

2 3 3

WATER BODY BUILT-UP ELEVATION

1 1 70%

LANDUSE LANDCOVER

30%

Land Use Land Cover classification Percentage ranking of the criteria

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Figure 5: DEM of the area showing the elevation range

Figure 6: Map showing areas that are suitable for the placement of reservoirs

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Conclusion and recommendations This study assessed piped water distribution system in Osogbo municipality. The result further confirmed the insufficient water supply (10, 000m3/day) from Erinle and Ede dams to the two reservoirs, which by all standard is far less to 33,154,800m3 required as daily consumption by the residents in the Municipality. With the result, it is very clear that potable water supply in Osogbo is also far below expectation of MDGs 7 and taken Osogbo as true representative of most urban centers in Nigeria, it is imperative that Nigeria will require more times before meeting the MDG for water supply in Nigeria. The result also revealed the present situation of piped water network distribution pattern in the study area as just about 32% of the total area was covered with the pipe network. The epileptic water supply through the pipes further suggests that the populace will no doubt have no access to potable water in the area. The study also observed that insufficiency in the access to potable water by the residents of the study area could be attributed to the following; • The current population of the metropolis exceeds the design population of the water scheme at inception.



With the frequency of power outages, the water corporation is handicapped in meeting its daily pumping requirements to the metropolis as it only pumps water for less than 7 hours and require a period of 3-7 days to complete distribution cycle.

The lack of maintenance culture for the frequent breakdown of facilities of the waterworks as most of the water wasted due to leakage from the broken and rust pipes. • Inadequate funding hampers the statutory function of the Osun state water corporation such as repairs and monitoring the facilities. The study also suggested for the expansion of the water scheme to meet more realistic demand for water as suitable sites for reservoir locations were mapped. So also was the need for repair of the damage and expansion of the existing water pipe networks to the new area of the metropolis. .



Acknowledgement. The contributions of Mr. O. A. Olayanju of GIS Laboratory, Department of Remote Sensing and GIS, Federal University of Technology, Akure on data analysis for this paper are highly appreciated.

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