Assessment of Groundwater Prospect and Aquifer Protective CapacityUsingElectrical Resistivity Method in Akole, Oke -Ata, Abeokuta North, Southwestern Nigeria

Abstract

Water is a fundamental resource and it is essential for life. Water is one of the world’s most extensively distributed resources that can be  found on the surface or under the ground. Theworkaimed to research the application of electrical resistivity methods to evaluate the  ground water potential and aquifer protective capacity using electrical resistivity methods in a part of Akole-Oke Ata, Abeokuta North,  Ogun State, Nigeria, with the following objectives; to deline ate the sub surface materials underlying and to determine the aquifer  characteristics of the study area. Ageophysical technique using vertical electrical sounding (VES) utilizing the Schlumberger  array configuration, with half current electrode spacing (AB/2) varying from1.0 to 20.0m was conducted at fifteen VES stations. The VES  data were interpreted qualitatively and quantitatively. The result shows that the Basement Complex terrain comprises 3 to 4 geo-electric  layers, viz; topsoil/gravel, clay, sand, clayey-sand, fractured basement, fresh basement, and Basement. Thelayer resistivities and thickness  obtained from the curves revealed that the fractured basement has the main aquifer type. A 1-D Electrical Resistivity Data  generated using WINRESIST software, revealed different curve types such as H, HA, KQ, KH, etc. Whereas, curve type H generated from  most curves having distinct minimum and maximum values, shows layers of unusually low and high resistivity at intermediate depths. The  Vertical Electrical Sounding result showed that the longitudinal unit falls between 0.02795 to 0.471 mhos, classifying the aquifer protective  capacity to be within the poor (6.7%), weak (40%), and moderate (53.3%)categories. VES 9, 10, and 13 were revealed to have high  groundwater potential and are thus good sites for developing a borehole well. The study has shown that the resistivity method is a reliable  tool for understanding subsurface geology and groundwater exploration of the area