Investigation of Aquifer Storage Properties and Groundwater Contamination Risk Potential using Electrical Resistivity Technique: A Sedimentary Environment Case Study

Abstract

Abstract This study involves the investigation of aquifer storage properties and contamination risk potential using electrical resistivity technique in Obot Akara and Ikot Ekpene Local Government Areas of Akwa Ibom State, southern Nigeria. The two counties are shown to comprise three to four lithological successions of sandy and gravelly layers with slight clay intercalations. Groundwater abstraction takes place in the third and fourth layers in the area at depths of 5.4 to 121.4 m depending on the locations. Two aquifer storage properties (aquifer specific yield and specific retention) were investigated. Accordingly, the results demonstrate that an inverse relation exists between the two storage properties. The aquifer specific yield and specific retention must respectively be greater and less than a threshold value of 0.15 for the aquifer to be prolific. On this basis, 94% of the study region is revealed to have good groundwater potential for sustainability of water boreholes. Groundwater contamination risk potential was investigated by using longitudinal conductance (LC) and geoelectric layer susceptibility index (GLSI) parameters. The LC results show that 87.5% of the study region has weak/poor protection while 12.5% has moderate protection against infiltrating contaminants. The GLSI results show that 21.9% of the area is typified with moderate susceptibility rating while the 78.1% left over has low susceptibility potential. The identified areas with weak/poor protection and moderate susceptibility are adjudged to have moderate/high groundwater contamination risk potential. These findings provide valuable guidelines for formulating sustainable groundwater utilization and management strategies in the area.