Resistivity Prospecting for Groundwater Potential at the Proposed Ibrahim Badamasi Babangida University Teaching Hospital, Lapai, Niger State

Abstract

Resistivity methods have been increasingly used for aquifer characterisation due to their high level of effectiveness. In this study, electrical resistivity survey was carried out at the Proposed Ibrahim Badamasi Babangida University Teaching Hospital Lapai Niger State Nigeria in order to study the groundwater potential with a view of determining the depth to the bedrock and thickness of the overburden protective capacity. Vertical Electrical Sounding (VES) using Schlumberger array was used to occupy thirty (30) VES stations using ABEM Terrameter (SAS 300) for the acquisition of apparent resistivity data. The field data obtained was analysed using computer software (IPI2win) which gave the secondary geoelectric parameters of depth, layer thickness and layer resistivities. The results revealed heterogeneous nature of the subsurface geological sequence comprising top soil (clayey-sandy and sandy-lateritic), weathered layer, partly weathered (fractured basement) and fresh basement. The resistivity value for the topsoil layer varied from 20Ωm to 600Ωm with thickness ranging from 0.5 to 7.2 m. The weathered basement had resistivity values ranging from 15Ωm to 593Ωm while the thicknesses varied between 2.75 and 33.04m. The fractured basement had resistivity values ranging from 201Ωm to 835Ωm and thicknesses having values between 11 and 20.4m. The fresh basement (bedrock) had resistivity values ranging from 1161Ωm to 3115Ωm with infinite depth. The depth from the earth’s surface to the bedrock surface varied between 2.5 to 47.75m. The VES 10, 11 and 19 had very good overburden protective capacity and can serve as good sites for borehole drilling.