Re-Construction of Palaeo-Sedimentation Processes of Aquifers underlying Igueben using Geo-Electrical Resistivity Signature and Borehole Data

Igueben is located in the central of Edo State, Nigeria. It has neighboring towns; Ogwa, Ugbegun, Ugiogba, Ebelle, and Ekpon. These towns have the same aquifer but significantvariations in the water table. However this study is intended to unravel the salient ancient hydrological processes that occurred in the study area which resulted in this variation. Vertical electrical sounding (VES) data and borehole data of the area are integrated to generate geo-electrical resistivity section of the area, to identify the aquifer trends, body, and shape to re-construct the palaeo-sedimentation processes of the aquifers that underlie Iguebe and the neighboring towns. The inversion model result for the seven VES conducted in the study area show that the curve types are HQA, AHA, A, AHA, AHA, HAQ, and AQA, respectively. These curve type suggested that the aquifer type is anarenite sandstoneaquifer that has been transported from a long distance. The geo-electrical pattern and shape show that Igueben and Ogwa (shallow marine) are the points of deposition from where other nearby towns (Ugbegun, Ugiogba, Ebelle, and Ekpon) sourced their aquifer by gravity settling from suspended sediments in water body into adjacent deep marine environment (Ugbegun, Ugiogba, Ebelle, and Ekpon).The study showed that Igueben and Ogwa are the hydraulic-head of the aquifer in the study area. The geological processes that had occurred in the study area during sedimentation are responsible for the variation in the water table in the study area.