INTERPRETATION OF GEOELECTRIC PSEUDO SECTION AND SEISMIC REFRACTION TOMOGRAPHY WITH BOREHOLE LOGS CARRIED OUT ACROSS A FUNCTIONAL BOREHOLE AT GARAJE-KAGORO AREA OF KADUNA NORTHWESTERN NIGERIA

Afuwai Gwazah Cyril

Abstract

Electrical resistivity and Seismic refraction surveys were carried out at Garaje Kagoro area of Kaduna State across a high yielding borehole to characterize the subsurface structures responsible for the high yield. Both the electrical resistivity method and the seismic refraction method show that the borehole location is underlain by four individual layers in agreement with the borehole log. The topsoil with a resistivity range of 50-140Ωm constitutes of wet brown sand and sandy clay which correlates well with the borehole log. The weathered basement which is the second layer constitutes of coarse/medium grain sand which correlates well with the borehole log. The resistivity value of the weathered basement layer ranges from 100-250Ωm. The depth to basement varies along the profile; however, averagely it is about 65m. Generally, the geophysical results revealed that the high yielding aquifer is a heterogeneous unconfined aquifer with a good yielding potential which have thick overburden deposition of fine-medium coarse grain sands. The electrical resistivity method show that the resistivity values of individual layers increases with depth. The seismic refraction method show that the velocity of individual layers increases with depth. Read full PDF

Keywords: Borehole, Resistivity, Seismic Refraction, Garaje-Kagoro

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