Stable isotope analysis of karst hydrological system: Mt. Velebit, Dinaric karst, Croatia

Mt. Velebit is a 145 km long mountain in the Croatian Dinaric Karst lying between the Adriatic Sea, the Ličko Polje and the Gacko Polje. It has been the subject of many research due to complex hydrogeological conditions resulting from intensive neotectonics and long lasting processes of karstification. There are many unknowns in the functioning of the Mt. Velebit’s hydrological system. The discovery of vertical and up to 1431 m deep caves during the last decades gives us the opportunity to gather new data “in situ” regarding the system’s hydrology. We used stable water isotopes of oxygen (18O, 16O) and hydrogen (1H, 2H) as natural tracers to expose water infiltration properties of the system.