Exploration for Groundwater and Delineation of Lineament Features using Geoelectrical Method in the Tanke Area of Ilorin, Kwara State, Nigeria
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Date
2019-05
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Nigerian Association of Mathematical Physics
Abstract
The exploration for groundwater and delineation of lineament features using geoelectrical method in the Tanke area of Ilorin, Kwara State, Nigeria was carried out. Twenty Schlumberger Vertical Electrical Soundings (VES) were carried out with a view to establishing the different subsurface geoelectric layers, the aquifer units and the lineament features. Data collected from several VES points using DDR1 resistivity meter equipped with an SAS 2000 booster were analyzed. From the quantitative interpretations of the data collected, using the usual method of curve matching with the Orellana-Mooney Master curves and 1-D forward modeling with IPI2WinTM v2.0 software, between three to five geoelectric strata were identified in the area. These include: the topsoil, the lateritic soil, the weathered basement, the fractured basement and the fresh bedrock. The weathered layer and the fractured basement constitute the main aquifer units. The type curves in the study area include: H, QH, AKH, A, HA and KH. The H type curves are predominant. The depths to bedrock at the chosen VES locations vary from 2.8 to 27.5 m with a mean value of 11.92 m in the study area. The depths to the top of aquifers range from 0.2m at shallowest point to 4.5m at the deepest point from the ground surface, with generally low resistivity values (≤ 100 Ω-m). The main river that drains the area coincides with the inferred lineament which suggests a structural control of the drainage. The general lack of thick overburden in the study area explains why the wells and shallow boreholes drilled in the area dry up during the dry season, a situation that makes the residents to engage in drilling deep boreholes sometimes as deep as 100m or more.
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Keywords
Exploration, Groundwater, Lineament features, Electrical Soundings, Weathered and Fractured