Multi-Method Geophysical Mapping of the Basement Complex Hydrogeology in Zamfara State, North West Nigeria

Zamfara State faces a dual water resource crisis driven by overextraction from shallow aquifers and agricultural water demand that outstrips recharge, yet a systematic hydrogeophysical map of the basement complex aquifer system at state scale has not previously been constructed. This study produces a state-scale hydrogeophysical framework for Zamfara State by integrating vertical electrical sounding data from 180 stations with aeromagnetic lineament analysis and satellite-derived groundwater indicators. VES data were collected across all 14 Local Government Areas using a stratified spatial design, ensuring representative coverage of different geological domains including granitic terrain, schist belts, and alluvial valleys. Geoelectric layer models were classified into aquifer potential categories using established Dar-Zarrouk parameter thresholds calibrated against yields from 85 existing boreholes. The aeromagnetic lineament map derived from first vertical derivative enhancement of airborne data provides a structural control layer showing preferred groundwater flow pathways. A multivariate statistical model combining geoelectric parameters and lineament proximity achieves a cross-validated area under the ROC curve of 0.84 in predicting borehole yield exceeding 1 litre per second. Application of the predictive model to unsampled areas produces a continuous aquifer potential map for the entire state. High-potential zones are concentrated in the NE-SW trending schist belt corridors and in alluvial valley systems adjacent to the Zamfara River and its tributaries. The map directly informs the prioritisation of borehole development investment under the Zamfara State Rural Water Supply Programme. Keywords: hydrogeophysics, basement aquifer, Zamfara State, VES, aeromagnetic lineaments