Groundwater potential evaluation using geoelectrical and analytical hierarchy process modeling techniques in Akure-Owode, southwestern Nigeria

Abstract

The complexity and heterogeneity of hydrological conditions in Akure-Owode of southwestern Precambrian basement complex of Nigeria largely control the availability of groundwater supplies in the area. Akure-Owode, being one of the four hydrogeological provinces in Sub-Saharan Africa is worst hit by poor access to continuous supply of groundwater resource throughout the year. Analytical hierarchy process (AHP) modeling technique in conjunction with geo-electric measurements was employed to unravel subsurface complexities and groundwater potential zones in the study area. Geophysical-derived groundwater potential conditioning criteria, namely bedrock relief (B), resistivity (R) and aquifer thickness (T) were synthesized by AHP pairwise comparison weighting and ranking technique to generate groundwater potential indices (GPIs) of the area. Raster-weighted overlay analysis were performed on the GPIs to obtain groundwater potential model (GPM) of the study area. The produced GPM was binned into low, medium and high groundwater potential prediction zones. The performance evaluation of the groundwater potential model using the spatial locations of prolific boreholes and hand-dug wells in the area indicates 80% success rate. Emerging from the vertical electrical sounding curve analysis, weathered (unconfined) and weathered/fractured (unconfined) aquifer types were identified in the area. Hence, the developed groundwater potential map in this study can be harnessed for optimal groundwater resource management of Akure-Owode area.