keywords: VES, VLF-EM, Integration, Groundwater Potentials, Ajaokuta, North Central
The study involves integrating the geology, electrical resistivity, and electromagnetic methods i.e. Vertical Electrical Sounding (VES) and Very Low Frequency Electromagnetic (VLF-EM) respectively, in delineating groundwater potential zones. Geological field mapping carried out within the study area reveals the major rock types within the study area as fine to medium-grained granitic gneiss, porphyritic granite, and migmatite of the Precambrian Basement Complex of South-western Nigeria. The VES result showed that there are four to five geo-electric layers in the study area The layers with their respective range of resistivity and thickness values are the topsoil comprising of lateritic clay 6.3 - 320.8 Ωm and 0.5 - 11.0 m; weathered basement 1.5 - 2228.2 Ωm and 1.2-22.7 m; confining fairly weathered basement 41.0 - 3284.6 Ωm and 5.2 - 87.1 m; weathered/fractured basement aquifer; 63.1- 2145.1 Ωm and 5.3 - 69.5 m and fresh basement 406.8 - 31456.2 Ωm with undefined thickness. These results reveal two curve types, i.e. HA and HK, and further characterized the groundwater potential zones within the study area into three; good (western and southern part), moderate (north-eastern part), and poor (central part) groundwater prospect. Also, the VLF-EM results correlate with what was obtained from the VES data. This suggests that the groundwater potential zones consist of water-bearing strata in the overburdened materials and weathered basement, with targeted aquifer depths ranging from 40 - 90m, which are mainly located within the migmatite and porphyritic granite rocks in the study area.