Lithologic characterization of Iguosa erosion site using geoelectrical techniques

Abstract

Considering the devastating menace of gully erosion for which lithology is one amongst several other agents that drives soil loss and gully erosion, Vertical Electrical Sounding (VES) and Electrical Resistivity (ERT) techniques were adopted to investigate subsurface lithology in Iguosa gully erosion site. PASI 16GL model resistivity meter was used in acquiring data for VES and ERT in the area under investigation. VES data acquired were processed both qualitatively and quantitatively, and geoelectric sections were generated using AUTOCAD software by combination of two or more interpreted VES results along a profile. ERT data were processed using Res2dinv software to an inverse model resistivity section. The geoelectric image generated were interpreted to obtain lithology of the subsurface. The analysis and interpretation of the subsurface image reveals presence of topsoil, sand, dry sand, clayey sand and coarse sand. The subsurface lithology within the study location is predominantly sandy. The result obtained from the resistivity of all profiles shows that erodibility increases with depth within this study area with corresponding high resistivity values. Due to the fact that sand within the study area is loose coarse and silty, which can give rise to high resistivity and causes erosion.