assessment of groundwater potential and aquifer vulnerability

Abstract

Groundwater constitutes the principal source of potable water in Erin-Ile, Kwara 
State, Nigeria, making a comprehensive assessment of aquifer characteristics 
essential for sustainable groundwater development and effective resource 
management. This study integrated Vertical Electrical Sounding (VES) employing the 
Schlumberger electrode configuration with Dar Zarrouk parameter analysis to 
evaluate groundwater potential and aquifer vulnerability across the study area. Eight 
VES stations were acquired and quantitatively interpreted to delineate subsurface 
lithological units and determine key hydrogeophysical parameters, including aquifer 
resistivity, thickness, depth, hydraulic conductivity, transmissivity, permeability, 
transverse resistance, and longitudinal conductance. The interpreted aquifer 
resistivity values range from 98.8 to 710.3 Ωm, while aquifer thickness varies 
between 7.03 and 37.87 m, reflecting significant spatial variability in aquifer 
properties. Estimated hydraulic conductivity ranges from 0.85 to 8.16 m/day, 
transmissivity from 5.94 to 282.15 m²/day, and permeability from 1010.79 to 
9757.11 mD, indicating moderate to high groundwater potential, particularly within 
the central and southern sectors of the study area where aquifer productivity is 
expected to be highest. Dar Zarrouk analysis further revealed longitudinal 
conductance values ranging from 0.0767 to 0.5774 mhos, suggesting that the 
aquifers possess predominantly moderate protective capacity against near-surface 
contamination. The integration of geoelectrical interpretation with derived 
hydrogeophysical parameters enabled the delineation of groundwater prospective 
zones and provided a reliable framework for evaluating aquifer productivity and 
vulnerability. Overall, the hydrogeophysical assessment identified the central
southern corridor of Erin-Ile as the most favourable zone for groundwater 
exploration, borehole development, and long-term sustainable groundwater 
exploitation, thereby providing valuable information for water resource planning and 
management in the area.