Characterization of Karst Terrain Using Geophysical Methods Based on Sinkhole Analysis: A Case Study of the Anina Karstic Region (Banat Mountains, Romania)

To understand karst topography, we must determine both the nature and the factors that are defining dissolution processes in soluble rocks, as well as the drainage network resulting from these processes. The goal of this paper is to understand the underground drainage direction configuration and, also, the factors that are involved in surface water drainage of the Anina karstic region. In this study we used two complementary geophysical methods, spontaneous potential (SP) and ground penetrating radar (GPR), applied in 5 sinkholes with a funnel shaped aspect. Four of these sinkholes are circular and one of them is elongated NW-SE direction. Three of the studied sinkholes are representing a chain of sinkholes orientated west-east. SP data describe the surface drainage, indicating drainage direction and/or moisture accumulation points. The GPR investigation utilizes electromagnetic pulses for the investigation of subsurface dielectric properties. GPR offers an image of the underground, showing possible bedding planes, in this case mostly along north-south orientations. Besides, in two GPR profiles, we could identify an object that could be a cavity, in that point were on SP grid the values indicate small values, pointing out a link between those two geophysical results. Using SP and GPR methods we were able to show that the bottoms of these depressions are retaining more humidity and soil. In addition, the GPR profiles outlined several subsurface “objects”, at a depth ranging between 20 and 40 meters, which need a more thorough analysis. Our future work is intended to enrich our field data using SP and GPR methods, to compare with our first results. Also, we intend to integrate electrical resistivity tomography measurements in our analysis for better subsurface characterization.