Electrical resistivity investigation of the groundwater potential in parts of Kwara State Polytechnic, Ilorin, Nigeria

Abstract

Vertical Electrical Soundings (VES) were carried out within the premises of the Institute of Technology, Kwara State Polytechnic Campus, Ilorin Kwara State, Nigeria, with the aim of determining viable aquiferous zones within the institute to alleviate the problems of well failure in the area. The study area is about 1.5kmsqures and is underlain by the Precambrian basement rocks comprising migmatite gneiss. Fifteen (15) VES were carried out using Schlumberger electrode arrayconfiguration with AB/2 equal to 70m. The VES data generated were processed and interpreted using partial curve matching method and computer iteration techniques. The interpreted data revealed three to four geoelectric sections with varied thicknesses and resistivity. The lateritic clay layer ranges from 53.1 to 302Ωm, the weathered horizon resistivity ranges from 22.7 to474.2Ωm while the competent rock has resistivity values greater than 220.3Ωm. The lateritic clay layer resistivity and thickness range from 53.1 to 302Ωm and 1.9 to 8.0m respectively, the weathered horizon resistivity ranges from 22.7 to 474.2Ωm and 4.4 to 11.7m respectively while the competent rock has resistivity values greater than 220.3Ωm and 6.1 to ∞m respectively. The third geoelectric layer constitutes the aquiferous zone in the 4-layer geoelectric section while the second geoelectric layer is the aquiferous zone in all the 3- layer geoelectric sections. Only VES station 9 out of the 15 VES stations shows good groundwater potential as revealed by the thick overburden and weathered layer with low resistivity value. VES stations 3, 4, and 13 show poor groundwater potentials while the others are non-aquifereous in nature.

Keywords: Basement, Parched Aquifer, Groundwater, Ilorin, Hydrogeology