APPLICATION OF VERTICAL ELECTRICAL SOUNDING (SCHLUMBERGER ARRAY) IN GROUNDWATER POTENTIAL INVESTIGATION

This study investigates the groundwater potential of Osubi, located in Okpe Local Government Area of Delta State, Nigeria, through the application of the Vertical Electrical Sounding (VES) method using the Schlumberger array. The research focuses on delineating subsurface lithological sequences and identifying aquifer zones using resistivity profiling. Field measurements were carried out across ten VES stations using the PASI-16GL Earth Resistivity Meter, with data processed and interpreted using curve matching and the WinRESIST software to generate geoelectric models. The results reveal a multilayered subsurface composed of resistive topsoil, intermediate fine-grained units, and deeper coarse sand layers with high resistivity values indicative of freshwater-bearing zones. These aquiferous units, occurring at depths ranging from 20 m to over 45 m, exhibit favorable hydrogeological characteristics such as thickness and protective overburden, suggesting high groundwater yield potential. The geoelectric sections derived from VES interpretation underscore the capability of electrical resistivity methods in identifying and mapping subsurface aquifer structures. The findings not only confirm the presence of significant aquifer systems within the Benin Formation but also emphasize the vulnerability of the shallow sandy horizons to contamination due to the absence of thick confining clay layers in some areas. This study contributes to the hydrogeological understanding of Osubi and similar Niger Delta environments, providing baseline data for groundwater development, borehole siting, and water resource management. It further recommends the integration of complementary geophysical techniques and the installation of monitoring infrastructure for long-term aquifer sustainability and protection.