Determination of Ground Water Resources in Elekuro and Environs, Abeokuta: Using the Geoelectric Method (Vertical Electrical Sounding)

Abstract

Geophysical investigation of Elekuro and environs, Abeokuta, South western Nigeria was undertaken to explore the potential for further ground water development, considering the depth, thickness, resistivity and layer at which water can be obtained. The geo-electrical method used in the survey is Vertical Electrical Sounding. Six Vertical Electrical Soundings (VES) were conducted using the Schlumberger configuration covering the entire area. The VES data were subjected to an iteration software (WIN RESIST) which showed that the area is composed of top soil, weathered layer, fractured layer and basement. The result of a quantitative interpretation of the VES data obtained in a geophysical survey are represented by a geoelectric section which shows the sequence and relationship between the subsurface lithologies. The weathered layer and the fractured zone have been identified as the aquiferous in the area. The weathered layer is thicker in VES 1 and thinnest in VES 2, while the fracture basement is thickest in VES 1. Based on low resistivity values, overburden thickness and Reflection coefficient, VES1 has the highest and brightest potential for future groundwater exploration and development in addition to the existing ones.The study area falls within the basement complex of Southwestern Nigeria. The rocks are Precambrian in age as they lie between the pan African orogenic belts.