Groundwater potential investigation using combined VLF and VES

This work is an assessment of groundwater in Oke-Agbe High School field located in Akoko North-West Local Government Area of Ondo State. The goal is to establish groundwater viability in this location based on a clear-cut relationship between Electrical Resistivity (VES) and Electromagnetics methods (VLF). Both methods were jointly used for investigation to determine overburden thickness, geo-electric layers and groundwater potential.The advantage of this combination is that the VLF technique was used as a reconnaissance survey to identify the best VES locations. The computer iterated data from the study area enabled us to delineate the area into high, medium and low water potential zones Results obtained in this study clearly showed the depth to the bedrock beneath the VES stations. The field was contoured to demarcate areas with thick overburden ( 10m), areas with medium overburden (between 5-8 m) and areas with relatively thin overburden (≤ 5m) marked as A, B, and C respectively. VES station 4 with infinite overburden thickness and VES station 6 with fractured basement are the only aquifer units within the entire school field where groundwater could be exploited and therefore, serve as high groundwater potential zones. However, it must be stated here that VES station 6 is the surest bet within the priority area for groundwater development. . This result from combined technique is more reliable than the investigation based on only one method of investigation for groundwater feasibility studies, especially were the subsurface is doubtful. JONAMP Vol. 11 2007: pp. 403-410