A comparative study of different electric imaging configurations in investigation of a fresh-saline groundwater interface

Electric imaging (EI) can be useful in solving various geotechnical-geoenvironmental problems. In this study, EI was applied to investigate a salinized soil ground in the NE Thailand for locating the interface between saline and fresh groundwater due to brine water pumping activity for salt production in the area. A manual electric imaging procedure was applied instead of using an automatic electric imaging with multi-cable and multi-electrode system. To enhance efficiency and production of the manual EI procedure, a comparative study was made on various configurations, i.e., dipole-dipole, pole-dipole, Wenner and Schlumberger. All of the arrays worked very well, but the Wemer configuration gave the best electric response with reference to a vertical interface of resistivity contrast, while the poledipole has the largest depth of investigation.