Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Abstract:
Hydro-geophysical investigation for deep fractured columns involving the Very Low Frequency Electromagnetic (VLF-EM) and the electrical resistivity methods has been carried out within the Federal Housing Estate Akure, Southwestern Nigeria. This was with a view to assessing the groundwater potential of the Estate. Four (4) VLF-EM and Horizontal Profiling (HP) traverses were established. Eighteen (18) Vertical Electrical Soundings (VES) were conducted at the investigated site. The VLF-EM data were presented as profiles and 2-D images. Horizontal Profiling (HP) data were also presented as profiles while the VES data were presented as geoelectric sections. The VLF-EM profiles and 2-D images identified conductive zones (suspected to be basement structures) which were confirmed by the subsurface geoelectric sections developed from the interpretation results of the Vertical Electrical Sounding (VES). The geoelectric sections delineated five subsurface geologic layers. These include the top soil, weathered layer, fresh basement, fractured basement and the fresh basement bedrock. The fractured basement constitutes the main aquifer unit within the study area. The weathered layer is generally thin and clayey. The confined fractured basement columns (Olorunfemi and Fasuyi, 1993) are characterized by relatively low resistivity values (82 � 602 ohm-m) and moderate to significant thickness (20.4 � 65.6 m). The relatively low fractured basement resistivity could indicate enhanced permeability due to significantly fractured density and tendency for moderate groundwater potential and yield. This study demonstrates the effectiveness of integrated geophysical investigation in groundwater potential assessment in a typical basement complex environment.

Keywords: hydro-geophysical, deep fracture, aquifers, delineation, basement rocks.

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