Assessment of Aquifer Vulnerability Using Multi-Criteria Decision Analysis around Akure Industrial Estate, Akure, Southwestern Nigeria

Abstract

This study is aimed at evaluating of aquifer vulnerability in a typical basement complex environment of Akure industrial estate, Akure, Southwestern Nigeria. A multi-criteria model is developed for achieving this aim; the vulnerability model which is based on topsoil resistivity, longitudinal conductance, thickness of layer overlying aquifer, and hydraulic conductivity of each sounding point across the study area is successfully used to evaluate the aquifer vulnerability of the area for future groundwater development programme in the area. Geophysical investigation involving vertical electrical sounding is carried out across the study area. A total of thirty one (31) vertical electrical soundings (VES) data were acquired using Schlumberger array with maximum half-current electrode separation of 100 m. Three to five geoelectric layers were delineated across the study area. The curve types obtained are the A, H, K, KH, HA, AA, QHA and KHA.The map of topsoil resistivity, longitudinal conductance, thickness of layer overlying aquifer, and hydraulic conductivity were generated and synthesized to producing the vulnerability map. The vulnerability map shows that the area is characterized by five zones; very low, low, moderate, high and very high. The mid-western, southeastern and closure at the northern part of the study area are delineated to be very low to low vulnerable zones, followed by the eastern and part of the western and central part of the study area which are categorized as moderate vulnerable zones, and finally the southern and northern part of the study area which are characterized by high and very high vulnerable zone.