Utilizing Geological and Geoelectrical methods in a GIS-based DRASTIC model of the Probable Groundwater Vulnerability in the Southern Nigerian Raffia Metropolis of Ikot Ekpene and its Surroundings

Abstract

The city of Ikot Ekpene is facing a significant issue with groundwater contamination. This is due to the rising amount of home and industrial waste caused by the increasing human population and various business operations in the area. This study seeks to evaluate the susceptibility of groundwater in the metropolis of Ikot Ekpene and its surrounding areas in southern Nigeria. It will utilize integrated geoelectrical and geological approaches within the GIS-based DRASTIC model. A total of twenty vertical electrical soundings (VES) were conducted in the region using the Schlumberger array. Based on the geological drilling data, the interpretation of the VES data suggests that the area consists of 3-4 geoelectric layers. The lithological succession in the area exhibits a range of sediment types, including fine and coarse sand as well as gravelly sands. Additionally, there are localized occurrences of clay intercalations. The third geoelectric layer, located at a depth of 9.0–86.6 m, is the primary aquifer that can be utilized in the region. The DRASTIC model included seven environmental parameters, including depth to the water table, net recharge, aquifer medium, topography, impact of vadose zone, and hydraulic conductivity, with the purpose of conducting a vulnerability assessment. The assessment of groundwater vulnerability ratings (GVR) reveals that 75% of the research region is classified as high vulnerability, 20% as moderate vulnerability, and the remaining 5% as low vulnerability. The studied area is predominantly characterized by moderate to high Groundwater Vulnerability Rating (GVR), which is likely attributed to the generally gentle topography and the presence of highly permeable geomaterials in the upper levels of the water table.