Aquifer Vulnerability Index Model for Vulnerability Assessment: A Case Study of Irewolede Estate in Ilorin, North-Central Nigeria

Abstract

An Electrical Resistivity Survey was conducted in the Irewolede Estate, located within the Ilorin Metropolis, with the objective of evaluating the susceptibility of the weathered geological layer to contamination. A total of 16 Vertical Electrical Sounding data points were collected and analyzed to delineate the geo-electric stratigraphy, assess hydrogeological implications, and evaluate aquifer vulnerability. The investigation identified five distinct geo-electric layers, including a shallow aquiferous layer exhibiting resistivity values ranging from 28.2 to 876 Ωm and thickness measurements ranging from 4.94 to 71.5 m. The spatial distribution of the Aquifer Vulnerability Index (AVI) indicated that the majority of the region exhibited moderate vulnerability, succeeded by areas of low vulnerability. Regions characterized by high and extremely low vulnerability were noted as small, isolated patches. In order to avert aquifer contamination, the study advocates for thorough geophysical and geotechnical investigations prior to the establishment of future landfills in the region. The findings of this research provide significant insights into the subsurface geological conditions and aquifer vulnerability, which can guide decisions regarding the appropriate placement of groundwater resources and the siting of landfills. By implementing proactive strategies, the potential risk of aquifer contamination can be effectively mitigated, thereby ensuring a sustainable and secure water supply for the community.