Integrated magnetic and electrical sounding investigation of groundwater potential zones in Federal University of Health Sciences, Ila-Orangun permanent site

Abstract

Groundwater exploration in crystalline basement terrains is often challenging due to the discontinuous and heterogeneous nature of aquifers. To address this, an integrated geophysical investigation combining ground magnetic profiling and vertical electrical sounding (VES) was conducted at the permanent site of Federal University of Health Sciences, Ila-Orangun, to delineate groundwater potential zones. Magnetic data revealed magnetic lows across traverses, indicative of a subsurface zone of intense weathering, fracturing or faulting. Sharp magnetic gradients further signified structural discontinuities, such as faults and lithological contacts, conducive to groundwater flow. VES models revealed predominantly four to five subsurface layers with aquiferous weathered and fractured zones. Traverse resistance identified thick conductive zones, while longitudinal conductance values were below 0.07 S, suggesting poor and weak natural aquifer protection. Hydraulic conductivity ranged from 1.00 to 22.03 m/day, while anisotropy coefficient ranged from 1.00 to 1.32, revealing near-isotropic to mildly anisotropic conditions, with localised structural control. Overall, the central-southern part of the study area is the most promising for sustainable groundwater development. Beyond the local context, this integrated workflow provides a transferable approach for improving groundwater resource evaluation in crystalline terrains globally, contributing to sustainable water supply in line with Sustainable Development Goal 6 (SDG-6): Clean Water and Sanitation.