EVALUATION OF GROUNDWATER POTENTIAL USING ELECTRICAL RESISTIVITY METHOD IN SOUTHWESTERN, NIGERIA: A CASE STUDY OF OKENUGBO, AGO-IWOYE

A number of abortive boreholes prompted this study. Okenugbo Area of Ago-Iwoye, Southwestern Nigeria was investigated for the evaluation of groundwater potential, the study area lies between Longitude N06°55.389̕-N06°55.384̕ and Latitude E003°55.001̕ and E003°54.959̕ respectively. Attempt to evaluate the subsurface geologic and Geoelectric properties that might contribute to the availability of low groundwater within the area and to identify areas vulnerable to high yield of groundwater for the purpose of the community was carried out.

Schlumberger Electrode Configuration of Eight (8) VES data acquired at random within the study area was used. The VES Data acquired were interpreted into a model curve using Winglink. From this interpretation five (5) different curve types were obtained from the acquired data. They are namely; - HA-type, QH-type, HK-type, A-type, H-type. HA- type is the dominated type of the curve obtained with characteristics of ρ₁> ρ₂< ρ₃< ρ₄at each layer which shows that the depth to fresh basement in the area is shallow.

The interpretation revealed that the groundwater potential in this area is very low except for the VES 2 and VES 3 which will give high yield of groundwater through hand-dug well or borehole. VES 1displays a very low resistivity value of about 67 ohm-metres gives proximity of having groundwater susceptibility, but the value rather suggests presence of archaeological materials due to ancient life of the area. Any borehole located at VES 5, VES 6, VES 8 will be abortive due to their lithology formations.

Schlumberger Configuration of Electrical Resistivity revealed variations in the lithologies and differences in geological and geophysical properties in the study.

Keywords: Groundwater, Electrical Resistivity, Okenugbo, HA-type, QH-type, HK-type, A-type, H-type.

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