Comparison and Integration of the Results Obtained Processing, Modeling and Interpretation of Electrical Tomography and GPR Data for Detection of Subsurface Shallow Targets and Structures

Every geophysical method has its own advantages and disadvantages. The integration of the results obtained surveys using various geophysical methods causes the weaknesses of a particular geophysical method to be covered by the other geophysical methods. For this, different exploration, engineering, environmental and other investigations using various geophysical methods usually provide more reliable results. In this research work, it is attempted to integrate the results of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) surveys in order to examine the advantages and weaknesses of each of the two methods, and finally, to present more accurate and more reliable interpretation as a result of this integration. The ERT method that is, in fact, one of optimal resistivity survey methods, renders acceptable results in complex geology areas. The GPR method as a high resolution non-destructive geophysical method, which is based on transmission of electromagnetic waves in the ground and recording the reflected waves the interfaces of the subsurface layers, is used for shallow subsurface investigations. In this research work, a water qanat was ed as a suitable target for detection by these two geophysical methods, and the, ERT and GPR surveys were carried out in an area enclosing the target. The results obtained processing, modeling and interpretation of the acquired data indicated that the GPR method, compared to the ERT method, had higher resolution than the ERT method. However, the ERT method, compared to the GPR method, had higher depth of penetration. The results of both methods were mainly in good agreement with each other in depicting features such as subsurface cavities, variation of the grain sizes of the subsurface sediments and water percolation the qanat to its surroundings. Furthermore, following the integration of the results of these two methods, it was found that the accuracy and reliability of the interpretation were considerably enhanced.