Hydrogeophysical groundwater potential zoning using VES for groundwater-quality monitoring in an arid carbonate aquifer, central Saudi Arabia

Groundwater is a critical water-supply and buffering resource in arid regions, yet groundwater development and protection in carbonate terrains remain uncertain because aquifer geometry, fracture permeability, and salinity-related resistivity . This study integrates 14 Schlumberger Vertical Electrical Soundings with a Hydrogeophysical Groundwater Potential Index (HGPI) and weight-sensitivity analysis to delineate groundwater potential in Qusur Al-Muqbil, central Saudi Arabia. Four-layer 1D inversion (RMSE = 3.12–5.83%) resolves a dry surficial cover (2–10 m; 21–154 Ω·m), a semi-confining argillaceous carbonate unit (0–37 m; 4–17 Ω·m), a fractured-limestone aquifer (58–109 m; 15–60 Ω·m), and an underlying conductive substratum (7.5–45.9 Ω·m) extending beyond the effective investigation depth. The aquifer shallows from approximately 42 m in the southwest/northwest to approximately 3 m in the northeast/east, and where thickness commonly exceeds 90 m . Within the 0.88 km2 convex-hull analysis mask, high and very high HGPI classes cover 0.60 km2 (67.6%). Alternative weighting scenarios retain 73.7–95.4% of the base-case top-20% priority zone and yield Spearman rank correlations of 0.919–0.988. The northeastern and eastern sectors are therefore the most defensible targets for verification drilling, aquifer testing, targeted groundwater-quality sampling, and recharge-zone protection. The VES–HGPI workflow provides a transparent and transferable decision-support framework for heterogeneous arid carbonate aquifers.