Groundwater Potential Evaluation in a Typical Basement Complex Environment Using GRT Index—A Case Study of Ipinsa-Okeodu Area, near Akure, Nigeria

Abstract

This study is aimed at evaluating groundwater potential of Ipinsa-Okeodu area, near Akure, Southwestern Nigeria. A multi-criteria model was developed for achieving this aim; the GRT model which is based on geology of each sounding point, resistivity, and thickness of the aquifer across the study area was successfully used to evaluate the aquifer potential of the area for future groundwater development programme in the area. Geophysical investigation involving vertical electrical sounding was carried out across the study area. A total of one hundred and two (102) vertical electrical soundings (VES) data were acquired using Schlumberger array with maximum half-current electrode separation of 150 m. Three to five geoelectric layers were delineated across the study area. The predominant curve types are KH, H, K and A. The maps of aquifer layer resistivity and aquifer layer thickness were generated and synthesized with the geology of the study area in producing the GRT model map/groundwater potential map. The groundwater potential map shows that the area is characterized by five groundwater potential zones; poor, low, moderate, good and high. The northwestern regions, north central and part of the southwestern regions are high groundwater potential zones, the northern and most part of southeastern zone are of moderate potential, while small portion in the southeastern and northern zones are of low groundwater potential.