Geoelectric investigation for the delineation of aquiferous zone in a basement complex are, Akure South Local Government area, Akure, Nigeria

  • AE Ekine
  • V Oku

Abstract

The electrical resistivity method for groundwater investigation in Akure South Local Government Area Akure, Ondo State, Nigeria has been attempted. In order to carry out the study, forty Vertical Electric Soundings (VES) using the Schlumberger Array with maximum electrode spacings of 100 m and 600 m were carried out at different locations in Akure. The quantitative interpretation of the VES curve involving partial curve matching using the two layer model curves and the corresponding auxiliary curves was adopted. Theoretical VES curves were generated from partial curve matching using a computer programme, which were later compared with corresponding field curves to obtain the final model parameters used in the analysis and subsequent discussion of the results. The result of
the resistivity survey showed that Akure urban consists of three to five geoelectric layers of varying thickness and resistivities. The thickness of the layers ranges from 0.5 m to about 90.0 m while the layer resistivities range from about 20 Ohm-m to 20,000 Ohm-m and above. The depth to aquifer ranges from 1.9 m to about 56.0 m. The study shows that the areas around Araromi flood plain (VES 9 and 16), Sports Stadium area (VES 14 and 22), Oke-Ijebu (VES 24 and 25), and the GRA areas
(VES 32, 33 and 34) are likely to be good locations for sustainable potable water. The study also reveals that the hydrogeological setting of the area below the top soil is prone to contamination and pollution especially the units overlain by sandy-clay and clayey-sand. The depth to drill which varies from location to location ranges from 5.0 m to 93.0 m. The lowest depth to aquifer is found at VES 5 (Mojere Quarters, Ilesha motor park) while the deepest depth is around VES 39 (St. Patrick's Primary School, Oke-Aro) and VES 4 (Akure/Ilesha/Ijare junction, Orita Obele).
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