Abstract

Vertical electrical resistivity soundings (VES) were carried out at Nkwelle-Ezunaka, Southeastern Nigeria to investigate the groundwater potential and aquifer protective capacity of the area. A total of ten soundings were carried out using ABEM Terameter SAS 1000. The VES data collected were interpreted using INTERPEX software and the results presented in terms of resistivity, thickness, depth and lithology. The lithology was inferred by correlating the result to the lithology log of one of the boreholes drilled in the study area and the geology of the study area. The VES result shows lithologic layers varying from 5 to 7. Water saturated sandstone and water saturated shaly sandstone constitute the aquifer units in the area at depth of 53.6 to 124.7 m, with their thickness ranging from 52 to 102 m as shown by the isopach map. The aquifer protective capacity was determined by calculating the longitudinal conductance and matching the values to known standards. The calculated longitudinal conductance varies from 0.00009 to 0.224 mhos. The interpreted VES results reveal poor aquifer protective capacity of the overburden layers.

Key words: Longitudinal conductance, transverse resistance, isoresistivity, geoelectric layers, vertical electrical sounding, inferred lithology, contamination.