GROUND WATER SUSTAINABILITY IN A CRYSTALLINE ROCK ENVIRONMENT USING ELECTRICAL RESISTIVITY AND MCDA APPROACH IN THE FEDERAL POLYTECHNIC ADO-EKITI, EKITI STATE, NIGERIA

Extensive growth in development, urbanization, and population has exacted more pressure on the availability and quality of groundwater resources. Human effort has been directed at solving groundwater scarcity in a crystalline basement rock environment through the identification of joints, cracks, fractures, faults, and weathered materials that may exhibit favorable disposition to groundwater accumulation for water sustainability. This research applied Multi-Criteria Decision Analysis (MCDA) in the context of Analytical Hierarchical Process (AHP) to geoelectric parameters to model Groundwater Potential Zones (GWPZ) in the Federal Polytechnic, Ado Ekiti, Ekiti State, Nigeria. The Electrical Resistivity method was adopted using 2D Resistivity Tomography and Vertical Electrical Sounding (VES) utilizing Schlumberger configuration. 2D Resistivity Tomography was delineated to determine vertical and lateral ranges in apparent resistivity of the subsurface geological properties favorable to groundwater accumulation and development. Eighteen (18) VES were acquired across the study area. The iterated VES results were used to generate geoelectric sections, maps, and second-order parameters. The MCDA in the context of the AHP technique was used to assign scores to various contributing parameters based on their relative contribution to groundwater potential. The GWPZ was generated by incorporating the selected and weighting seven important defined variables (Coefficient of anisotropy, overburden thickness, aquifer resistivity, aquifer thickness, storativity, transmissivity, and hydraulic conductivity) in the Surfer 12 environment in reflection to their groundwater availability. The groundwater potential was categorized into high, moderate, low, and very low. Very low to low groundwater potential characterized the entire study area, occupying 75%, with moderate to high occupying 25%. The findings revealed that the study area was characterized by very low to low groundwater potential. This research will assist in the development and monitoring of groundwater occurrences by decision policymakers to improve recharge techniques, especially in very low and low groundwater recharge zones.