Geoelectrical Investigation of Groundwater Potential At Riol Farm, Owode, Abeokuta, Ogun State
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Date
2016
Authors
Adeoti, Lukumon
Ijezie, N.T
Adegbola, R.B
Ojo, A.O
Afolabi, S.O
Adesanya, O.Y
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of the Nigerian Association of Mathematical Physics
Abstract
Geoelectrical investigation was carried out in order to solve the problem of drilling unproductive boreholes in RIOL Farm situated at Owode, Abeokuta in Ogun State. Fifteen (15) Schlumberger Vertical Electrical Sounding (VES) with current electrode spacing (AB) ranging from 2 m to 1000 m were acquired using PASI resistivity meter. The VES data were processed and interpreted using partial curve matching and computer iteration technique using WinRESIST software. The qualitative analysis reveals that the rising curves are dry sand devoid of groundwater while the descending parts of the VES curves are indicative of wet sands which could serve as potential aquifer. Four geoelectric sections generated from the interpreted VES results show four to six geo-electrical layers which correspond to topsoil with resistivity ranging between 45.0-993.9 ohm-m and thickness range between 0.5-1.0 m, lateritic clayey sand with resistivity ranging between 61.8-2328.0 ohm-m and thickness range between 1.2-5.5 m, sand/sandstone having resistivity range of
between 1003.4-9575.9 ohm-m and thickness range between 4.2-114.8 m, sand with resistivity value ranging from 318.9-1581.2 ohm-m and thickness range between 5.1-78.9 m and consolidated sandstone / ironstone with resistivity value between 23245.5-4388.7 ohm-m. The quantitative analysis reveals that sands at the upper layer are dry within the depth of 2.2 – 69.8 m and appear to be unsaturated while sands at the depth not less than 80 m in VES 2, VES 9 and VES 15 are wet (saturated) and recommended for drilling. Thus, the wet sands denote aquifer units in the study area. Based on our recommendation, the location of VES 15 was drilled and yielded a
productive borehole within a depth of 110m.
Description
Keywords
Schlumberger Array , Aquifer , Geoelectric Section , Resistivity , Borehole Log