Assessment of groundwater repositories in Edem, Southeastern Nigeria, using vertical electrical sounding

Scarcity of drinking water has been a major challenge in Edem, southeastern Nigeria. Thus, an electrical resistivity study was carried out in twenty-one locations across Edem, employing vertical electrical sounding. The study aims at investigating groundwater repositories through the estimation of aquifer geohydraulic parameters and corrosivity of the area. Resistivity, depth and thickness of each layer were realised after the measured resistivity field data were interpreted using manual and computer software packages. The results give a resolution of three to six geoelectric layers, with a total of nine generic curve types namely KQH, KHKH, KHK, AAK, AKQ, KHA, KH, KQQ and AKHK. The results show that the depth and thickness of the aquifer layer range from 39.2 to 161.3 m and 24.8 to 147.6 m respectively. Hydraulic conductivity values having a mean value of 2.1822 m/day range from 0.0121 to 14.0931 m/day. Values of transmissivity range from 0.8607 to 458.0727 m2/day and porosity ranges from 25.5831 to 32.6457%, while tortuosity ranges from 0.281 to 0.301. From the results, the fourth layer was identified as harbouring most of the aquiferous zones. Contour maps were generated to show the variations of the geohydraulic parameters across the area. Plots of these parameters show their good correlation coefficients. The result delineates 4.76% of the study area as corrosive and 76.19% as essentially non-corrosive while 9.52% are both moderately and mildly corrosive. This study will aid in divulging areas with higher groundwater potentials and areas with economical extraction of groundwater. © 2021, Saudi Society for Geosciences.