Geoelectrical Survey for Delineating Groundwater Potential Zones in Jigawa State

This study employs vertical electrical sounding to delineate groundwater potential zones in Jigawa State, North West Nigeria. Jigawa State's rapidly growing population and expanding irrigated agriculture have intensified demand for groundwater, yet systematic hydrogeophysical investigation is limited, resulting in a high rate of unproductive boreholes drilled without geophysical guidance. This study acquires Schlumberger VES data at 30 stations distributed across Dutse, Birnin Kudu, and Hadejia local government areas. Maximum current electrode half-spacing of 250 metres provides adequate depth of investigation for the multi-layer alluvial sedimentary and basement complex sequences. IPI2WIN software inverts the apparent resistivity curves to produce layer resistivity and thickness models. Spatial variograms are used to interpolate layer parameters to produce depth-to-water-table and overburden thickness maps. Findings reveal a productive alluvial sand and gravel aquifer at depths of 30 to 80 metres in the Hadejia River floodplain corridor, characterised by resistivity values of 50 to 200 ohm-metres and hydraulic conductivities estimated at 8 to 18 metres per day. The basement complex terrain in Dutse shows less predictable aquifer conditions, with productivity strongly correlated with weathered zone thickness above 25 metres. Eleven priority borehole sites are recommended combining maximum overburden depth, intermediate resistivity indicating saturated sands, and minimal distance to existing unserved communities. Two sites are subsequently drilled and validated with yields of 3.5 and 5.2 litres per second. The study recommends hydrogeophysical investigation as mandatory before all rural borehole commissioning in Jigawa State.

Keywords: VES, groundwater potential, Jigawa State, alluvial aquifer, borehole siting.