ASSESSMENT OF GROUNDWATER POTENTIAL FOR RURAL WATER SUPPLY SCHEME USING GEOGRAPHIC INFORMATION SYSTEM (GIS) IN EDE NORTH LGA OF OSUN STATE NIGERIA

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Department of Engineering

ABSTRACT
Groundwater serves as a primary source of water supply in rural areas of Ede North Local Government Area (LGA) of Osun State, Nigeria. However, low access to drinking water coupled with pollution due to agricultural practices has been common problems in this LGA.This research was aimed at assessing the groundwater resourcesstatus of Ede North LGAusing Geographic Information System (GIS). Key hydrological and climatic parameters, most of which were acquired from Landsat 7 (ETM), ASTER were digitalized in GIS environment. The respective parameters were assigned weightages and their attributerangedand ranked with reference to groundwater occurrences or pollution potential. The resulting GIS layers were overlain using overlay function of ArcGIS and further integrated one over the other using GIS add function. Finally the study area was classified into three different groundwater potential zones. Over 82km2out of 112km2of the study area was classified as high and moderately groundwater potential zones. The groundwater of the study area was also assessed quantitatively using Krishna model. The groundwater potential was estimated as 26.8million cubic meters annually.Analysis of groundwater pollution potential indicated that out of total area of the LGA, 27.6% of the area equivalent to 31Km2 is highly vulnerable to groundwater pollution. The climatic variation of the study area indicated that rainfall and temperature increase at 0.031mm and 0.36oC respectively. The assessment of rural water supply scheme for investment plan and gaps to be filled to meetSustainable Development Goals (SDG)-6on universal coverage to water Supply was performed, the result revealed that 353 numbers of Boreholes and rehabilitation of 15 numbers dysfunctional scheme will be required with total cost of NGN940,332,124. Generally the result obtained from this research showed that GIS and the models used provide a powerful tool in the assessmentsof groundwater resources for effectiveplanning and management. The study area is viable for rural water supply scheme siting. The amount of groundwater available is sufficient to meet the immediate and remotely domestic water demand of 2.0m3/year and 3.21m3/year respectively withexpected domestic water supply demand average increase rate of 3.43% annually while the public groundwater use rate of 7.48% and 12.0% for 2015 and 2030 respectively. It is therefore recommended that Motorized and hand pump schemes be situated in area demarcated as high and moderate potential respectively while high risk area should be avoided for well siting pending the detail assessment for pollutants identification and remediation measures.