Assessment of Aquifer Protective Capacity and Groundwater Vulnerability Using VES-Derived Longitudinal Conductance in Iwo, Southwestern Nigeria

Adetunji Adeniji; Ajani Olumide; Kolawole Tolulope

doi:10.62292/njap-v2i1-2026-58

Authors

Adetunji Adeniji
adetunji.adeniji@fuadsi.edu.ng

FUADSI, Osun State
Ajani Olumide
Bowen University
Kolawole Tolulope
The Polytechnic Ibadan

Keywords:

Geophysical method, Longitudinal conductance, Groundwater investigation, Protective capacity

Abstract

Investigation of groundwater vulnerability is indispensable for sustainable aquifer management, principally in areas experiencing rapid population growth and increasing anthropogenic pressure on water resources. This study employs the vertical electrical sounding (VES) method to investigate aquifer protective capacity using longitudinal conductance, a geoelectrical parameter that serves as a quantitative indicator of groundwater vulnerability investigation. In this study, six VES stations were acquired across the study area and interpreted using one-dimensional layered-earth inversion to determine subsurface resistivity distribution and the thickness of overlying lithologic units. The longitudinal conductance (S) was calculated as the sum of the ratios of layer thickness to resistivity for all layers. The results revealed that the overburden thickness ranges from 3.8 to 35.1 m, the bedrock resistivity ranges from 545.3 to 3353.4 Ωm, and the calculated longitudinal conductance values vary from (0.13345 to 0.250887 S), indicating principally weak to moderate protective capacity, which suggest varying degree of groundwater vulnerability across the investigated VES stations. The results showed that in terms of aquifer vulnerability, low values suggest more vulnerability to surface contamination, whereas higher longitudinal conductance and thicker overburden suggest enhanced protective capacity. Therefore, the study emphasized that the VES-derived longitudinal conductance offers a vital background data for groundwater protection and management; however, they represent a preliminary vulnerability assessment.

Dimensions

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Assessment of Aquifer Protective Capacity and Groundwater Vulnerability Using VES-Derived Longitudinal Conductance in Iwo, Southwestern Nigeria

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