Groundwater Exploration in a Heterogeneous Basement Complex Environment Using Integrated Geophysical Methods

Abstract

The integrated very low frequency of electromagnetic (VLF-EM) and vertical electrical sounding technique (VES) of electrical method were carried out to explore for groundwater resource in a very complex terrain within Akure metropolis. The VLF data was acquired at 10m interval along five traverses (TR 1 to 5). The conductive zones mapped on EM profiles and 2-D pseudo-section suspected to be fracture or localized features were further probed using a VES technique. A total number of 12 VES points were acquired to ascertain the fractured or contact zones. Relatively high conductivity is observed around the portion marked as F1, F2 and F3. VES conducted on these conductive zones acknowledged the suspected fractured or geologic contacts zone observed on the EM profiles. VES 1, 7 and 11 acquired on the conductive zones delineates both weathered and fractured layers with the resistivity values ranging from 80 to 490Ωm and 228 to 935Ωm respectively. These layers are considered to favour groundwater accumulation. VES acquired on the high resistive zones of EM profiles also showed high resistivity which may be not be prolific for groundwater development. The outcomes of this research may serve as a guide for sustainable water supply and water management plan.