Integrated Geoelectrical and Vulnerability Modeling for Groundwater Quality and Aquifer Protection Assessment in Obowo Local Government Area, Imo State, Nigeria

Abstract This study integrates geoelectrical and hydrogeological methods to assess aquifer characteristics, groundwater quality, and vulnerability in a 20-location survey. Vertical Electrical Sounding (VES) using the Schlumberger array was conducted, with data processed in WINRESIST to derive resistivity, thickness, depth, and elevation. Aquifer indices—formation factor, porosity, and longitudinal conductance—were evaluated to determine groundwater potential and protective capacity. Results showed spatial variability, with fresh, low-mineralized groundwater in VES 1, 2, 10, and 14, while VES 19 had high porosity but low resistivity, suggesting mineralization. Vulnerability analysis using DRASTIC, AVI, GOD, and GODL indicated generally low susceptibility, though VES 6, 15, 17, 19, and 20 showed higher risk from high permeability, thin overburden, or shallow aquifers. GODL highlighted VES 19 and 20 as priority zones for protection. Therefore, most of the area has good aquifer quality and moderate to strong protection, but localized zones require targeted management.