engleski

Stable isotope investigations in the Kupa drainage basin (Western Croatia)

During a campaign lasting from October 27 to November 21, 2010 sixty-seven water samples were taken from sites along the three hundred kilometers long course of the Kupa River. We interpret the oxygen isotopic composition of the high part of the catchment of the upper Kupa River, comprising Čabranka River and its smaller tributaries down to Karlovac with higher Delta 18O-values of river waters, as predominantly influenced by maritime precipitation from the Kvarner Bay. The catchment of lower Kupa River and its tributaries, from Karlovac down to Sisak, and also the southern catchment of Dobra- and Korana River predominantly are influenced by precipitation out of more continental (humid) air masses. This more continental influence does not necessary imply precipitation out of drier air masses from the continental side but may also be the result of rainout influences on the isotopic composition of primary maritime air moisture. The high values of the deuterium excess of Kupa River waters (d= 11 to 17 promile) are similar to those reported by Vreča et al. (2006, Tab.2) for the station Zavižan - Mt. Velebit (d= 12 to 17 promile) and disagree with those of the station Zagreb-Grič (d= 7 to 10 promile). We therefore conclude that precipitation from the Adriatic side predominantly charges both karst water and river water of the Kupa catchment.

Kupa drainage basin; Western Croatia; stable isotopes; meteoric water line

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