Groundwater Detection in Basement Complex of Northwestern Nigeria using 2D Electrical Resistivity and OffsetWenner Techniques

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Author(s) bdullahi N.K | Iheakanwa, A
Pages 529-535
Volume 2
Issue 7
Date July, 2013
Keywords 2D resistivity survey, offsetWenner technique, anisotropy, fractures.
Abstract

A two-dimensional resistivity survey of Kaduna Polytechnic Demonstration Secondary School, Northwest, Nigeria was conducted using the Wenner alpha electrode configuration. Measurements of three profiles separated by 20 m were investigated in the study area with the aid of an ABEM SAS 300C instrument. A manual data collection technique was employed with the aim of determining the groundwater potential of the study area by investigating the degree of weathering and fracturing in the weathered profile developed above the crystalline basement. The observed resistivity data were inverted using the RES2DINV code. Results from the 2D inverse models of resistivity variation with depth suggest the occurrence of potential aquifers mostly in weathered/fractured zones within the traps or below it. Also, the resistivity models produced indicate the presence of fracture zone that could be exploited for groundwater extraction. To verify the interpreted results (Fractures) from the 2D resistivity data, azimuthal resistivity measurement using the OffsetWenner technique was conducted beside the observed anomalous zone. Cartesians azimuthal graphs of RD1 and RD2 and coefficients of anisotropy (λ) obtained from the OffsetWenner VES measurements at greater depths (18 - 24 m) indicate homogeneously anisotropic ground suggesting fracturing at these depths, consequently, complimenting the 2D resistivity data.

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