Geoelectrical Investigation of Groundwater Potential around the Cattle Yard, Ovia North-East Local Government Area, Edo State, Nigeria

Abstract

Groundwater scarcity around the Cattle Yard in Ovia North-East Local Government Area, Edo State, Nigeria, necessitates investigation to identify geoelectric conditions that may support groundwater occurrence. A vertical electrical sounding (VES) survey was conducted using a Parsi (A.C) Earth Resistivity Meter, and the Schlumberger electrode configuration with a maximum current electrode separation (AB) of 500m. The geodetic coordinates of the vertical electrical station were recorded using a Global Positioning System (GPS).  The VES data collected during the field survey were processed and interpreted using IPI2WIN software. Six subsurface geoelectric layers were interpreted with layer boundaries occurring at depths of approximately 0.916m, 1.02m, 2.34m, 7.47m, and 24.40m. Resistivity values range from 0.675Ωm to 126912Ωm, indicating marked electrical heterogeneity. The interpreted units comprise materials tentatively associated with cemented sandstone or gravel, dry sand or lateritic gravel, wet or saturated sand, and lateritic or sandy material. The fifth layer with a resistivity of 146 Ωm and a thickness of 16.9m may represent a relatively conductive sandy or lateritic interval that could have groundwater bearing potential. However, resistivity alone cannot establish saturation or aquifer productivity. The sixth layer has an undefined thickness and depth and exceptionally low resistivity of 0.675 Ωm. It is therefore interpreted conservatively as a highly conductive zone that may reflect clay rich material, mineralized water or another conductive lithology. The results provide a preliminary geoelectrical basis for groundwater assessment, but confirmation through borehole drilling, lithological logging and groundwater quality testing is required before development decisions are made.