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Identification of the hydrogeological and hydrochemical characteristics – northern part of the Dinaric karst in Croatia

Insufficient understanding of hydrogeological, hydrochemical and dynamic relations of the Internal Dinarides in Croatia had a key role in selection of a case study for the project CAMARO- D (EU, Interreg Danube 2014-2020). New hydrogeological insights will be the basis for the future water management and flood protection of karstic part of Kupa River catchment area and its surroundings. Complex geological setting of the research area, which encompasses two hypsometric levels of spring and sinking zones, is mainly caused by structural-tectonic relations (and significant human interventions – tunnels, hydroelectric power plants, canals…). The case study comprised monitoring on 18 springs and 3 surface water- flows with the purpose to determine the hydrogeological characteristics of this complex aquifer system defined as the boundary between Internal and Outer Dinarides. The southern boundary of the research area is placed north of Kapela Mtn and Plitvice Lakes, northern boundary is the boundary between Dinaric karst and Pannonian basin in Croatia, while eastern and western boundaries coincide with state boundaries with Croatia and Bosnia and Hercegovina (East) and Slovenia (West) – partially following Una and Kupa rivers’ streams. This karst terrain is significantly different than other parts of the Dinaric karst terrains in Croatia. It is fluviokarst, often called shallow karst. Hydrochemical characteristic of groundwater has been studied by sampling and analyzing physic- chemical parameters: oxygen content, electrical conductivity, pH, temperature, total organic carbon, major anions (HCO3 −, Cl−, SO42−) and cations (Ca2+, Mg2+, Na+, K+), as well as heavy metals. In addition, stable isotope contents (δ18O, δD) is being monitored in spring and rain water in monthly intervals from beginning of 2018 till the end of 2019. Karstification processes of different rocks from this area will also be explored within this study. Geological and hydrogeological characteristic of this area will be presented in this paper, as well as first results of physic- chemical parameters in order to identify hydrogeochemical facies.

hydrogeology, boundery, Dinarides, hidrogeochemistry, CAMARO-D

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