Integration of Elevation, Lithology and Geoelectric Parameters Using Analytical Hierarchy Process for Groundwater Potential Evaluation in Part of Akure Metropolis, Southwestern Nigeria

Abstract

This hydrogeophysical study was carried out in order to proffer solutions to inadequate water supply plaguing Obanla-Obakekere, in the campus of Federal University of Technology, Akure (FUTA) Nigeria. The depth sounding method engaged the Schlumberger configuration. Three to five geoelectric layers were delineated from the results. The layer resistivities vary from 33 - 548 Ω-m, 13 - 6110 Ω-m, 42 - 90,232 Ω-m, 60 - 89,806 Ω-m and 711 - 100,000 Ω-m in the topsoil, weathered layer, weathered basement, partially weathered/partially fractured basement and the presumed fresh basement respectively. Elevation and lithology data were combined with six geoelectrically derived parameters (aquifer resistivity, aquifer thickness, longitudinal conductance, transverse resistivity, longitudinal resistivity and coefficient of anisotropy) to evaluate the groundwater potential of the study area. Each of these hydrogeological/hydrogeophysical significance parameters were presented as map showing different groundwater potential zones in the area. The maps were integrated using the Analytical Hierarchy Process (AHP) method. The groundwater potential map (GPM) shows that the northcentral area, the western and eastern flanks area has high to very high groundwater potential. These zones constitute about 40% of the study area, while the remaining segments, classified as moderate and low prospect, constitute about 38% and 22% respectively. The model GPM was validated using evidence of producing wells/boreholes. 13.89% of the producing wells/boreholes falls within the low groundwater potential zones, 30.55% falls within moderate groundwater potential zones and 55.56% falls within high and very high potential. This study can serve as guide for future groundwater development efforts in the study area.