The study area, located in Holy Karbala City, used geotechnical data collected by utilizing three boreholes drilled to a depth of 30 m for soil investigation, in which 32 samples for each borehole, for a total of 96 samples for all. and ERT survey, three types of electrode arrays were applied in this study: dipole-dipole, Wenner, and Wenner-Schlumberger configurations, respectively, using a Terrameter LS2 instrument with a spacing of 4 m between the used electrodes. The purpose of this study is to compare the geotechnical investigation data with the electrical resistivity tomography survey data collected at the site. The survey was carried out along three profiles, and the Res2dinvx64 software was used to process, analyze, and interpret the gathered data. The results of the soil investigation revealed three layers in the soil profile, while the electrical resistivity survey measurements indicated the presence mainly of three layers with resistivity values ranging from 1.74 to 744 Ω.m. Some geotechnical properties showed a direct correlation with the electrical resistivity data, while others revealed an inverse correlation. The groundwater depth, which was identified by the resistivity survey, was 4 m, consistent with the three boreholes' results. This study demonstrates a good agreement between the geotechnical method and the electrical resistivity tomography survey. The resistivity method can be effectively used to determine soil properties, reducing the economic costs and even saving time. The electrical resistivity tomography method showed good integration with the soil investigation method, revealing the horizontal and lateral extent of the layers and their depths. In contrast, the drilling method, although accurate, provides information limited to a specific point based on the borehole width and does not confirm the lateral extensions, which can be more reliably obtained through the electrical method for more detailed information.
Alameri et al. (Tue,) studied this question.