Differentiating Clayey Soil Layers from Electrical Resistivity Imaging (ERI) and Induced Polarization (IP)

Electrical Resistivity Imaging (ERI) method is one of the most promising techniques which is well suited for the applications in the fields of geohydrology, environmental science and engineering. The present work is aimed to show the efficiency of 2D Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) in probing the subsurface soil for site investigation and differentiating the clayey soil layers as it is a common practice to measure the IP sounding along with resistivity for correct interpretation of field data. The study has demonstrated the practical application of 2D ERI and IP tomography along 7 lines using Wenner- Schlumberger array. The data analysis comprises of 2D inversions using the RES2DINV software, thus 2D electrical resistivity and IP imaging sections have been obtained. The depth of investigation was 4 m, and resistivity values range from electrical layers were recognized: the upper layer with high resistivity (7-71 ohm.m) represents the loamy soil extends to a depth around 1.3 m; and the second layer with low resistivity ( high electric zones are appeared reflecting the inhomogeneity in deposits. The IP values are ranging from -2 to 17 mV/V showing good confirmation with resistivity data, where high chargeability are associated with low resistivity. The study reveals that combining IP with resistivity surveys is recommended since IP is, sometimes, very effective in relieving ambiguity in interpretation.