Preliminary Lithologic Deductions for Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria, using Vertical Electrical Sounding Method

Research Article

Akaninyene Okon Akankpo and Ma

Abstract

This work is about geoelectric investigation involving forteen vertical electrical sounding carried out in Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria. The total current electrode spread varied from 400 to 500 m and this depended on access roads, topography and general infrastructure. The survey was aimed at investigating the resistivity of consolidated and unconsolidated formations of the study area and the depth of the Aquifer. The ABEM Terrameter, signal averaging system (SAS) 4000 was used in carrying out the soundings. Data obtained were interpreted using the RESIST software. The usual high and low resistivities of the Benin Formation caused by changes in lothologies were obtained. Aquifer resistivity varied from 249.70 to 4192.30 Ωm. The number of layers ranged from four to six in the area, while the total thickness ranged from 9.20 to 484.50 m. The curve types significantly obtained in the area were: A, HA, HK, KH, AK, HAK, KHA, and HKH. The curve models distributed fairly in the area have good prospect for groundwater potential due to low resistivity values obtained from H- and K-curve types which can translate into saturated sand beds of significant water wells. Three litho-and hydroresistivity cross sections were drawn which shows that the area has four distinctive layers defined as; top loamy, lateritic sand, medium grained sand (water bearing formation) and the conducting layer which is clay formation. Efforts should be made to check the quality of water in such a region, since aquifer in the region is located at shallow depths from the surface of the earth.

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