Assessment of Groundwater Potential and Aquifer Characterization in Abakaliki Urban Area Using Integrated Geophysical Methods

Abakaliki, the capital city of Ebonyi State, experiences recurrent water supply challenges attributed to inadequate characterization of local aquifer systems. This study employs vertical electrical sounding (VES) combined with horizontal profiling to assess groundwater potential and characterize aquifer geometry in the Abakaliki urban area. Forty-five VES stations were established across the study domain using the Schlumberger array with maximum half-electrode spacing of 300 m. Acquired data were processed and inverted with WINRESIST software, yielding geoelectric layer models that were correlated with lithological logs from existing boreholes in the area. Three to five geoelectric layers were delineated, comprising topsoil, weathered zone, fractured basement, and fresh basement. Aquifer zones are primarily identified within the fractured basement complex and the weathered zone at depths ranging from 25 m to 88 m. Dar Zarrouk parameters computed from the layer models indicate that aquifer protective capacity varies from weak to good across the study area, with the southern portion of Abakaliki showing the most favorable conditions for groundwater development. Transmissivity estimates derived from electrical parameters suggest high-yielding aquifer conditions in the central and southeastern zones. Isopach maps of the weathered layer reveal a pronounced deepening toward the axis of the Abakaliki Anticlinorium, which appears to control groundwater accumulation locally. These findings provide an updated hydrogeophysical framework for borehole siting and groundwater resource management in Abakaliki. The results are particularly relevant for urban water supply planning under current climate variability conditions.

Keywords: vertical electrical sounding, aquifer characterization, Dar Zarrouk, Abakaliki Anticlinorium, groundwater potential