GROUNDWATER EXPLORATION FOR ACHIEVERS UNIVERSITY TEACHING HOSPITAL.

ABSTRACT This study investigates the groundwater potential of the proposed Achievers University Teaching Hospital site in Owo, Ondo State, Nigeria, located within the complex crystalline Basement Complex terrain of southwestern Nigeria. The research employs an integrated geophysical approach, combining Vertical Electrical Sounding (VES) and Audio Magnetotelluric (AMT) techniques, to delineate aquifer-bearing zones andrecommend optimal borehole locations for a sustainable water supply critical to the hospital’s operations, including patient care, sanitation, and medical procedures. The Basement Complex, characterized by migmatite-gneiss complexes, schist belts, and Pan-African granites, presents challenges for groundwater exploration due to its heterogeneous and discontinuous aquifers, primarily confined to weathered regolith and fractured bedrock zones. The VES method, utilizing a Schlumberger array, mappednear-surface layering, identifyingthree to four geoelectric layers: topsoil, laterite, partlyweathered/fracturedbasement, and fresh basement. VES results revealed K-type curves (90%) and H-type curves (10%), withVES 4 indicating the highest groundwater potential due to a thick, conductive weathered layer (183.2 Ωm). The AMT method, leveraging natural electromagnetic fields, provided deeper subsurface imaging up to 300 meters, identifying low-resistivity zones (0.3–1.0 Ωm) indicative of water-bearing fractures. Recommended drilling depths ranged from 60 to 90 meters, with medium to high groundwater yield potential. The integration ofVES and AMT methods enhanced the reliability of aquifer delineation, confirming moderate groundwater potential across the site. The study’s findings underscore the efficacy of combining geoelectric and electromagnetic techniques to reduce borehole failure rates in crystalline terrains. By identifying viable drilling locations, this research ensures a reliable water supply for the hospital, addressing a critical infrastructure need. Additionally, it contributes to the broader understanding ofgroundwater exploration in southwestern Nigeria, offering a replicable model for similar settings. The results advocate for integrated geophysical approaches to improve water security inhealthcare facilities, supporting operational efficiency andpublic health standards in regions lacking municipal water systems.