Determination of hydraulic properties from geoelectrical parameters in Raya Valley aquifer, Northern Ethiopia

The Raya Valley, situated along the western margin of the Afar Rift in northern Ethiopia, relies heavily on groundwater for agriculture and rural livelihoods. The area is structurally complex, with aquifers mainly hosted in alluvial deposits and the underlying basalt formations. Despite the availability of hydrogeological and geophysical data, integrated quantitative assessments of aquifer properties remain limited. This study characterizes the valley’s aquifers by combining geoelectrical and hydrogeological datasets. Forty-five paired Vertical Electrical Sounding (VES) measurements and well logs provided resistivity (ρ) and layer thickness (t), which were used to compute Dar-Zarrouk parameters (transverse resistance, R; longitudinal conductance, S) and derive hydraulic conductivity (K) and transmissivity (T). The main aquifer consist of saturated alluvial sediments (4–27 Ω·m; 53–292 m thick) and underlying fractured basalts (3–185 Ω·m; 4–68 m thick). These units exhibit moderate to high groundwater potential (K = 1–34 m/day; T = 120–2210 m²/day) and moderate to excellent protective capacity (S = 2–60 Ω⁻¹). Strong empirical relationships derived from the co-located data (T = 1.671 R – 990.79, R² = 0.95; K = 1.4423ρ – 5.4117, R² = 0.98) confirm the predictive value of VES data for estimating aquifer properties. The study establishes a validated, cost-effective methodology for aquifer assessment in the Raya Valley and demonstrates its applicability to similar rift-related environments, emphasizing the importance of local petrophysical calibration for sustainable groundwater management. • Geoelectrical methods predict aquifer hydraulic properties. • Robust models (R²>0.95) for transmissivity (T) and hydraulic conductivity (K). • VES enables cost-effective aquifer mapping in data-scarce regions. • Framework scalable to African semi-arid aquifers with similar geology. • Advances hydrogeophysics via integrated characterization.