GEOPHYSICAL INVESTIGATION OF GROUNDWATER POTENTIAL OF A SITE IN OBALE AREA OF AKURE, NIGERIA.

Abstract

Electrical Resistivity method using Vertical Electrical Soundings (VES) were carried out at a site in Aba-Oyo area FUTA Southgate area, Akure, Nigeria, with the aim to access groundwater potential of the site. The study area is underlain by crystalline rocks of the Precambrian basement complex of the Southwestern Nigeria. Twelve (12) VES were carried out using Schlumberger electrode array configuration with AB/2from 1 to 65m. 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 top soil layer ranges from 44 to 181?m, lateritic clay layer ranges from 20 to 174?m, the weathered horizon resistivity ranges from 20.0 to 424.0?m while the competent rock/fresh rock has resistivity values greater than 424.0.3?m. The top soil layer resistivity and thickness ranges from 44 to 181?m and 0.4 to 2m, the lateritic clay layer resistivity and thickness range from 20 to 174?m and 1.7 to 6.0m respectively, the weathered horizon resistivity ranges from 20.0 to 424.0?m and 1.4 to 7.4m respectively while the competent rock has resistivity values greater than 424.0?m and ?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. VES station 2, 7, 9 stations shows good groundwater potential as revealed by the thick overburden and weathered layer with low resistivity values. VES stations 1, 4, 5, 6, 8, 10 and 12 shows moderate groundwater potentials while VES stations 3 and 11 are non-aquifereous in nature.