Assessment of Groundwater Potential and Mapping of Aquifer Protective Capacity in Parts of Bauchi Metropolis, Northeast Nigeria, Using Dar-Zarrouk Parameters derived from Geoelectrical Resistivity Data

Abstract

Sustainable groundwater governance in urban crystalline basement terrains requires reliable 
assessment of groundwater potential and aquifer vulnerability to surface-derived contamination. This 
study evaluates groundwater potential and aquifer protective capacity within Unity Estate, along Jos 
Road, Bauchi Metropolis, Nigeria, using Dar-Zarrouk parameters derived from geoelectrical 
resistivity data and supported by hydrochemical information. Ten Vertical Electrical Sounding (VES) 
stations were established using the Schlumberger electrode configuration, with current electrode 
half-spacing (AB/2) extended to 60 m. Quantitative interpretation of the VES data identified 
conventional A-, H-, and HA-type curve signatures, reflecting variations in subsurface lithology and 
geoelectrical conditions. Layer resistivities and thicknesses obtained from the interpreted models 
were used to calculate the Dar-Zarrouk parameters comprising longitudinal conductance (S), 
transverse resistance (T), and coefficient of anisotropy (λ). Longitudinal conductance values ranged 
from 0.013 - 0.890 S, indicating predominantly weak aquifer protective capacity across the study 
area. Transverse resistance varied from 4,776 - 21,010 Ωm², demonstrating considerable 
subsurface heterogeneity, while anisotropy coefficients of 1.23 – 1.58 indicate moderate to 
significant geoelectrical variability. Vulnerability classifications were further corroborated using 
hydrochemical data from selected wells. Three groundwater potential zones were delineated. High
potential zones were associated particularly with VES stations displaying A-type curves 
characterised by low-resistivity layers at depth, interpreted as weathered or fractured basement 
aquifers. Aquifer protective-capacity mapping revealed that 60% of the investigated area possesses 
weak-to-moderate protective capacity and is consequently susceptible to surface-derived 
contamination. The integrated geoelectrical and hydrochemical approach provides a robust 
framework for groundwater exploration, aquifer vulnerability assessment, and sustainable 
groundwater-resource management in Bauchi Metropolis.