Assessment of Groundwater Potential and Aquifer Protective Capacity at Proposed Filling Station Site, Federal University OyeEkiti, Southwestern Nigeria

Abstract

The potentiality of groundwater and aquifer protective capability at the proposed Filling Station Site, Federal University Oye-Ekiti, Southwestern Nigeria were evaluated using geoelectrical method. The geoelectric investigations involved 2-D tomography using dipole-dipole configurations and Vertical Electrical Sounding (VES) technique adopting the Schlumberger array. Fifteen (15) VES stations were occupied on five profiles using Min-Res resistivity meter measuring current electrode spacing (AB/2) of 50 m. The data were plotted on a bi-log graph to produce VES curves. Four curve types H, A, HA and HKH were delineated. The H type curve occurred most in the area with 53.3%. A curve type consists of 6.7%, HA occupied 33.3% while curve HKH occupied 6.7% of the study area. The study revealed three to five geoelectric layers as: topsoil, weathered layer, partly weathered layer, partly weathered/fractured basement and fresh basement. The layers presented the following resistivity values: topsoil (124 – 547 Ω-m), weathered layer (49 to 505 Ω-m), partly weathered layer (330.3 to 2619 Ω-m), partly weathered/fractured basement (212.9 Ω-m) and fresh basement (668 - 236839 Ω-m). The longitudinal conductance ranging from 0.055- 0.061 mhos was delineated in the study area. The aquifer potentials of the area revealed good protective capacities having 80% protective capacity rating and poor protective capacity rated about 20%. Groundwater potential were recommended in six VES stations with resistivities ranging between 66 to 981 Ωm with depths ranging from 10.5 to 15.0 m in the study area. The area assessed could be classified as having low to moderate groundwater potential.