Use of electrical resistivity method for investigating geological and hydrological conditions at proposed site for Institute of Technology, University of Moratuwa

Abstract

Resistivity survey is one of the geophysical methods which can be used to identify subsurface ground conditions. The research is focused on determining the bed rock depth, variation of soil overburden thickness and areas suitable for ground water exploitations at the proposed site for Institute of Technology, University of Moratuwa by using the Vertical electrical sounding. The survey was carried out using Schlumberger electrode configuration along three main profile lines, with 18 resistivity points. The results of the survey were provided 2-3 distinct geo-electrical layers overlying the bedrock. The first thin upper layer represents of Sandy Silt/sandy gravel and second layer corresponds to lateritic soil. The third represents the saturated soil materials with less resistivity. The forth layer corresponds to the bedrock and the depth ranging from 8 to 26m from the surface. Geo-electrical results based upon 1-D models, which were created by IXlDv3 software, provide a satisfactory approximation of the various soil and rock components. Based on the above results, it is confirmed the soil overburden in the Northern part of the site, constitutes an aquifer, with a thickness of about 1.3m above the bed rock covering an area of about 100 m2.