AQUIFER DEPTH INVESTIGATION USING VERTICAL ELECTRICAL SOUNDING (VES) IN FUPRE SPORT CENTRE

Groundwater is a critical natural resource, particularly in the Warri area of the Niger Delta region of Nigeria, where most communities depend on boreholes for potable water. The shallow nature of aquifers in this region makes them highly susceptible to contamination from surface and near-surface activities. Accurate delineation of aquifer depths and subsurface lithological sequences is therefore essential for sustainable groundwater development and management. This study was carried out at FUPRE Stadium and Ugbomoro to characterize the subsurface geoelectric layers and identify productive aquifer zones using geophysical methods. The primary aim of this study is to ascertain the aquifer depth in FUPRE Stadium and Ugbomoro using geophysical investigation techniques. Specifically, the study seeks to delineate the subsurface geologic sequence, determine geoelectrical parameters including layer thicknesses and resistivities, and identify the depth and extent of aquifer horizons in the study areas. The findings are intended to provide essential data for informed borehole siting and groundwater development in the region, particularly in light of the growing population and increasing risk of aquifer contamination from shallow water tables. The Vertical Electrical Sounding (VES) technique, using the Schlumberger electrode configuration, was adopted for data acquisition across three traverses in the study areas. The Schlumberger array was selected for its superior vertical resolution and accuracy with depth. An Omega Resistivity Meter was used to inject electrical current into the subsurface through current electrodes, while potential electrodes measured the resulting voltage differences. The acquired apparent resistivity data were processed and interpreted using the WinResist computer iteration program, which generated 2D subsurface geoelectric models that were matched with standard curves for lithological interpretation. Three geoelectric sections were modeled from the acquired and computed geoelectric parameters. Results indicate that the subsurface in the study areas is underlain by four to five distinct geoelectric layers, identified lithologically as topsoil, sand, dry sand, clay, and wet sand. VES data from FUPRE Stadium revealed a potential aquifer zone characterized by medium-grained sand with a thickness exceeding 20 meters. At Ugbomoro, two traverses identified confined, deeper aquifer zones at estimated depths of 24.9 m and 22.9 m respectively, indicating better-protected groundwater resources compared to the shallower aquifer at FUPRE Stadium. Layers exhibiting high resistivity values were interpreted as sand, consistent with their large grain and pore sizes which offer greater resistance to electrical current flow. The Vertical Electrical Sounding survey successfully delineated the subsurface stratigraphy and aquifer levels at FUPRE Stadium and Ugbomoro. The geoelectric models revealed aquifer depth ranges of 20.6 m to 24.9 m, with Ugbomoro hosting a more protected and deeper confined aquifer relative to the shallow aquifer at FUPRE Stadium. The lithological sequence identified corresponds to the shallow Benin Formation of the Niger Delta Basin. It is recommended that boreholes installed in shallow aquifer zones be accompanied by water treatment measures, and that further surveys be conducted during the dry season to assess seasonal variability in groundwater levels.