HYDROGEOPHYSICAL DELINEATION OF GROUNDWATER POTENTIAL IN DOHO, GOMBE STATE, NIGERIA: INTEGRATION OF GEO-ELECTRICAL RESISTIVITY AND LITHOLOGICAL MODELING FOR SUSTAINABLE WATER RESOURCE MANAGEMENT

Abstract

The weathered and fractured aquifers in Doho (Gombe State, Nigeria) are heterogeneous, but the spatial variation of aquifer thickness, permeability, and protective capacity is only poorly constrained, which does not allow for reliable borehole siting and sustainable groundwater management. Manual and computer-assisted curve matching was used to interpret 10 vertical electrical soundings (VES) that were acquired to define 3-5 geo-electric layers per site. The layer resistivity and thickness were used to calculate the following petrophysical parameters: Dar Zarrouk parameters (longitudinal conductance, transverse resistance, formation factor, anisotropy ratios, and petrophysically inferred hydraulic conductivity (K) and transmissivity. Geostatistical tools such as descriptive statistics, correlation analysis, and spatial interpolation were used to map the hydrogeological properties and to identify potential drill sites. The interpreted resistivities were between 9.7 and 9,454.8 Ω·m, and the thicknesses of the various layers lay between 0.5 and 114.4 m. The range of inferred K was 3.75 to 322.17 m/day (median ≈66–80 m/day), and the range of point transmissivity was ≈1.8 to 9,665 m2/day with several values outside this range being flagged for validation. The VES02, VES05, and VES06 results indicated very high transverse resistivities (5,828–6,516 Ω.m²) and moderate–high S values (0.118–1.202 mhos) with good transmissivity and protection capacity while the results of VES07 and VES08 showed very low conductance and negligible aquifer thickness. The integration of VES-derived resistivity, Dar Zarruk parameters, and robust statistics provided a defensible ranking of groundwater prospects, identifying targets appropriate for sustainable borehole development (VES02, VES05, and VES06), and areas of low prospect (VES07 and VES08). These results contribute to SDG 6 (clean water and sanitation) in the sense that informed decisions can be made to explore groundwater resources cost effectively, with awareness of risk, and prioritize groundwater borehole testing and aquifer protection.