Integrating Geophysical and Hydrogeologic Layer Susceptibility Indexing for Aquifer Vulnerability Evaluation at Ilere Locality, Akure-Ijare Road, Southwestern Nigeria
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Abstract
Groundwater vulnerability assessment was carried out in the Ilere community on the Akure-Ijare road in Nigeria, aimed at classifying the area into zones of vulnerability. A total of fifty-nine Vertical Electrical Soundings (VES) were obtained by using the Schlumberger array with a maximum half current electrode spacing (AB/2) of 100m. The layer resistivity and thickness (geoelectric properties) of the covering strata were interpreted to characterize the subsurface conditions. Four geoelectric unit layers were identified: topsoil, lateritic layer, weathered/fractured basement and fresh basement. Aquifer vulnerability was analyzed in three models, namely GOD (Groundwater occurrence, Overlying lithology, and Depth to water table), longitudinal conductance, and Geo-electric Layer Susceptibility Index (GLSI). The results show that the overburden has a poor to moderate protective capacity in general, largely as a result of thin topsoil (0.2-5.2m) and variable resistivity values (25.6-1225.5ohm-m). The longitudinal conductance model showed poor to weak protective classes and thus has low attenuation capability against the infiltration of contaminants. The GOD and GLSI models consistently resolve into very low, low, and moderate vulnerability areas, with low vulnerability being dominant. However, moderate vulnerability zones are more noticeable in the Southern region. The combination of several geoelectric models offers a reliable basis for groundwater vulnerability mapping for basement terrains. The findings indicate the need to be careful of the site of potential sources of contamination, such as septic systems and waste disposal facilities, away from vulnerable zones in order to ensure sustainable development of groundwater.
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Copyright (c) 2026 Samson Oyine Ankeli, Oluwatomiloba Alex Adetunji , Awwal Ayomide Garba, Moses Olawale Ogunsola, Nelson Ayomide Bodede, Abdulgafar Opeyemi Kolawole (Author)
This work is licensed under a Creative Commons Attribution 4.0 International License.
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