Geophysical surveying in water-covered and swampy areas is particularly challenging. This paper presents a new survey strategy for such surveying that integrates ground penetrating radar (GPR) and resistivity image profiling (RIP) methods at the water surface to investigate geologic structures beneath rivers, ponds, and swamps.
Two test sites, a pond and a lake, have been selected to evaluate this new survey strategy. Experiments in both areas have been successful in delineating the structure of underlying gravel layers. The depth of water and shallow structures obtained from GPR data provided an effective constrain during processing of RIP data. Deeper structures were delineated using RIP data. The integration of GPR and RIP methods conducted at the water surface was successfully applied to map the Hsincheng fault crosscutting the Tourchyan River in Hsinchu County.
This paper shows that the use of GPR and RIP at the water surface is efficient in mapping geological structures beneath water. The proposed approach suggests the potential for conducting geophysical surveys along rivers and drainage canals in urban areas, places where roads and buildings impede other methods designed to detect active fault.