Hydrogeochemical and isotopic evidences for definition of tectonically controlled catchment areas of the Konavle area springs (SE Dalmatia, Croatia)

Increased human activities in the karst areas may result with unwanted impacts on environment, especially on groundwaters. This problem fostered reinterpretation of geological and hydrogeological relationships in the area of Konavle (SE Croatia). Detailed geological mapping enabled better insight into lithological and structural relationships in the area, especially concerning accumulation of groundwater in the karst underground of the hinterland. Thick succession of carbonate rocks of different permeability in the hinterland resulted in deep and complex reservoirs communicating mainly through tectonically predisposed zones. Aquifer dynamics is especially increased during the periods of high rainfalls and snow thawing in the hinterland. Four major springs, located along the tectonic contact between thick succession of Mesozoic carbonates and barrier composed of Palaeogene (and Neogene?) clastic rocks were observed. They show variable hydrogeochemical and isotopic values as a result of different altitudes, but also as a result of different catchment areas divided by important transversal fault systems. Since sporadically increased orthophosphate contents indicate anthropogenic influence presented preliminary results request careful monitoring and international cooperation to protect these sensitive transboundary catchment systems.

► Four major springs in the Konavle region (S Croatia) are tectonically controlled.
► Springs occur at the tectonic contact between carbonates and clastic rocks.
► Subcatchments are divided by important transversal fault systems.
► Springs show variable hydrogeochemical and isotopic values.
► Increased orthophosphate contents in waters require international cooperation.