Delineation of Groundwater Aquifer and Subsurface Structures of Some Selected Areas in Jema’a Local Government Area of Kaduna State, Nigeria using Electrical Resistivity

Abstract

This study aims to identify shallow groundwater Aquifer and Subsurface Structures of Some Selected Areas in Jema’a Local Government Area of Kaduna State, Nigeria using Electrical Resistivity. Eighteen vertical electrical sounding (VES) surveys were conducted using the Schlumberger array and the apparent resistivity from the obtained VES measurements were interpreted using curve matching inversion to obtain depth, thickness, and resistivity of various subsurface layers across the study area of interest which were eventually used to deduce the lithology and subsurface conditions of the area. The Vertical Electrical Sounding (VES) results revealed variations in the subsurface geo-electric characteristics across the study area, with the interpreted curves showing different geo-electric configurations, including H-, A-, and K-type curves. The H-type curves, characterized by a resistive–conductive–resistive sequence indicate the presence of relatively conductive intermediate layers that may represent weathered and/or water-saturated formations and therefore constitute potential aquifers zones. The A-type curve, characterized by progressively increasing resistivity with depth suggesting a transition from relatively conductive near-surface materials to more resistive weathered or fractured materials and ultimately competent basement, with groundwater occurrence potentially associated with the weathered or fractured zone overlying the basement. The K-type curve indicated a relatively resistive intermediate layer underlain by a more conductive formation, which may represent a deeper saturated or fractured zone and thus a potential groundwater-bearing horizon. Overall, the VES results suggested that groundwater occurrence within the study area is mainly controlled by the presence, thickness and degree of weathering and fracturing of subsurface. Based on the VES results, it is recommended that groundwater development should focus on locations characterized by relatively thick and moderately conductive weathered and/or fractured formations, which constitute the most promising aquifers zones within the study area. The identified low-resistivity zones should however, be validated through borehole drilling and lithological logging because conductive responses may also be associated with clay-rich materials. Integration of VES with ERT, geological mapping and structural information is recommended to improve the delineation of groundwater-bearing formations.