APPLICATION OF ELECTRICAL RESISTIVITY METHODS FOR GROUNDWATER ASSESSMENT IN BALOGUN, IBADAN

A geoelectrical survey employing Vertical Electrical Sounding (VES) was conducted in the Balogun area of Ibadan, Southwestern Nigeria, to delineate aquifer units and assess the groundwater potential of the region. Located within the Precambrian basement complex of Southwestern Nigeria, the area is predominantly underlain by quartzite, quartz schist, undifferentiated gneisses/schists, and augen gneiss formations. A total of ten VES stations were surveyed using the Schlumberger electrode configuration with a maximum half-current electrode spacing of 100 meters, facilitated by the Allied Omega Resistivity Meter.The collected field data were plotted on bi-logarithmic graphs and interpreted using partial curve matching techniques in combination with computer-aided modeling through the WINRESIST software. Interpretation of the VES results revealed five geoelectric layers: topsoil, lateritic soil/clay, quartzite and quartz schist, weathered basement, and fractured basement. Two key aquiferous units were identified—weathered basement and fractured basement—with resistivity values ranging from 41–310 Ωm and 118–653 Ωm respectively.The weathered basement, primarily composed of sandy material, exhibits an average thickness of approximately 26.5 meters and is capable of yielding a substantial quantity of groundwater. The fractured basement aquifer, occurring at depths between 5.7 and 68.2 meters, was observed in 40% of the VES points, indicating its potential in enhancing groundwater discharge.A groundwater potential map was produced by integrating geoelectric parameters from the delineated aquifer units. The area was categorized into zones of low, moderate, and high groundwater potential, with roughly 70% of the study area falling into moderate to high potential zones. These findings suggest that the Balogun area holds promising prospects for sustainable groundwater development, which could play a crucial role in addressing potable water scarcity and improving essential amenities for local residents—especially in regions where both aquifer units are present