Preferential Water Flow Pathways Detection in Sinkholes Using Self-Potential (SP) Method. The Study Case of Anina Karst Region (Banat Mountains, Romania)

Abstract

Limestone covers about 4500 km2 in Romania, meaning about 2% from the country surface, being specific for the karst of the temperate zones due to its landforms, terrain diversity and the amplitude of the exo and endokarst particularities. Carbonate rocks are spread in the mountains and sub-mountains areas, with the most compact and the largest surface of this type of rocks in the Banat Mountains, more exactly in the Resiţa-Moldova Noua Synclinorium. The aim of this study to examine the use of the self-potential as geophysical method in detection of water flow and water resources in shallow karst depressions (sinkholes) in the Anina Karst Region, Banat Mountains, Romania. The self-potential (SP) method—also known as spontaneous potential—is founded on the measurements regarding the natural or spontaneous potentials that are forming in the ground. Our SP approach in several sinkholes in the Anina Karst Region shows that most of the anomalous zones with positive spontaneous electric potential are localized in the middle of the sinkholes, indicating the higher retention of water within the bottom part of the karst depressions. Also, the most of the values showing negative anomalies are situated in those parts where the karrens are developed. SP method applied in the Anina Karst Region, Banat Mountains, Romania, has shown the feasibility of this geophysical method in the study of water circulation in shallow karst environment. Since sinkholes are landforms that favor the fast circulation of the water from the surface into the underground, the SP approach could be a feasible method to study aquifers and the presence of contaminants in karst aquifers since water is a very important resource in karst areas. Moreover, SP method is reliable in characterization of shallow karst topography research and this geophysical method can be combined with other geophysical method in karst terrain analysis, methods like GPR and ERT.