The evaluation of groundwater potential: Integration of the electrical resistivity method and Geographic Information System (GIS) In Afikpo, Ebonyi State, Southeastern Nigeria

This study assesses groundwater potential in the Afikpo area of Ebonyi State, southeastern Nigeria, using an integrated approach combining electrical resistivity (ER) and Geographic Information Systems (GIS). The study area spans 84.36 km², including towns like Ehugbo Afikpo, Afikpo, Ndibe, and Ozara, bounded by coordinates Latitude 5°50'00"N to 5°55'00"N and Longitude 7°54'00"E to 7°59'00"E. The primary goal was to evaluate groundwater potential using Vertical Electrical Sounding (VES) with the Schlumberger array and GIS-based Analytic Hierarchy Process (AHP). A total of 20 VES points revealed seven geoelectric layers, with the main aquiferous units identified as wet and saturated sandstones. Apparent resistivity values in these layers ranged from 0.27 Ωm to 3298.30 Ωm, with thicknesses between 5.25 m and 248.20 m. Hydraulic conductivity values ranged from 0.20 to 1324.36 m/day, and transmissivity ranged from 1.55 to 80926.69 m²/day. The findings indicate that 15 out of 20 VES points have moderate to high groundwater potential (>50 m²/day). The GIS-AHP analysis categorized the area as predominantly low to moderate potential (64.56 km²), with smaller zones of very low (7.52 km²), high (12.90 km²), and very high (0.11 km²) potential. Compared to other regions in the Benue Trough, Afikpo shows more favorable groundwater conditions. The integration of GIS-AHP and ER methods proved effective in assessing groundwater potential, highlighting the value of combining traditional geophysical techniques with modern GIS-based analysis.