Combining geophysical techniques and multi-criteria GIS-based application modeling approach for groundwater potential assessment in southwestern Nigeria

A new approach of modeling very low frequency–electromagnetic (VLF–EM) and vertical electrical sounding (VES) data with a view of evaluating groundwater resources potential via application of GIS-based multi-criteria technique is investigated in this study. On eight VLF–EM traverses established in the site, 40 VES locations were combed. The acquired geophysical data (VLF–EM and VES) were processed applying Fraser/Karous–Hjelt filter and Win-Resist program geophysical software to determine the area subsurface geophysical parameters. Five hydrogeologic maps were produced based on the results of the interpreted geophysical parameters. The produced hydrogeologic maps were assigned suitable weights and different rankings to the individual classes boundary within the maps using the standard Saaty’s scale principle in the context of analytical hierarchy process (AHP) data mining technique. A raster-based empirical GIS model was developed for integrating the hydrogeologic maps to compute the groundwater potential index (GWPI) values in the range of 1.02–2.82 for the study area. Based on the estimated GWPI results, a final map zoning the area into low (0.0930–1.3922), medium (1.3922–1.9109) and high (1.9109–2.8173) groundwater potential classes was produced in GIS environment. The prediction accuracy of the produced potential map was established via cross-validation and in situ well correlation analysis. The results of the study established a new approach of modeling geophysical data for exploring groundwater productivity potential in the study area.