Estimation of Hydraulic Properties of Aquifer Systems Using Geophysical Methods
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Date
2018
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Published by Department of Civil Engineering, University of Ilorin, Ilorin, Nigeria
Abstract
Determining aquifer characteristics is important in the sustainability and management of groundwater resources. Estimating aquifer properties by means of pumping test is financially cost and requires much time, therefore, applying geoelectric method in characterizing aquifer properties is an alternative method and cost effective. Geoelectric method was employed to determine hydraulic characteristics of groundwater aquifer systems in the rural localities of Ilorin, Northcentral Nigeria. Twenty (20) VES data were collected using Schlumberger array with a maximum half current electrode (AB/2) spacing of 100m. Sounding curves were initially interpreted by partial curve matching which gave resistivities of the layers with thicknesses and later inverted by IPI2 WIN software. The characteristics nature of the curves obtained from the VES data shows that the study area consists of three to five geoelectric layers. The results of the interpretation indicates that top soil possess resistivity and thickness ranges between 44.1- 862Ωm and 0 – 2.5m, second layer which is lateritic layer possess resistivity and thickness between 106 - 2001 Ωm and 0.6 – 10.3m, third layer is weathered basement having resistivity and thickness ranges from 22.3 – 166 Ωm and 3.1 – 52.0m while the fourth layer is fractured basement with resistivity and thickness between 78.4 - 138 Ωm and 14.8 – 71.1m and final layer is fresh basement which possess resistivity ranges between 40.1 – 136 Ωm. The hydraulic characteristics of the aquifers in the area determined from geoelectric parameters shows that hydraulic conductivity ranges between 0.16 – 24.8 m/day, transmissivity between 0.5 – 408 m2 / day and porosity was determined in the laboratory from collected field core samples with values ranges between 26 – 41% and these implies that aquifer systems in the area have tendency of transmitting water that good for sustaining water need of the area. This study has proved the usefulness and effectiveness of geoelectric method in characterizing groundwater aquifer systems.
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Keywords
Aquifer systems, Geoelectric, Hydraulic conductivity, Transmissivity, Porosity, Rural area