engleski

Channel processes and sedimentation in the Kupa River (Croatia)

Introduction Channel processes and sedimentation of the 300 km long Kupa River have been studied first time, after some previous research describing sediment pollution [1, 2, 3]. This river basin is of supraregional interest: besides its central position in Croatia, it is shared by two neighboring countries (Slovenia and Bosnia and Herzegovina) and is of strategic importance due to its rich water resources. Also, some of its parts in karstic areas are protected as national parks. Results, Discussion and Conclusions The generally meandering course starts from a karstic spring and flows to the plains with braided channels. The river basin material varies in size from bulders to fine sand. The bouldery and gravelly marginal bars and channel bars are quite conspicuous in the upper part and sandy point bars characterize some locations of the meander bends. Grain size data were used to predict sediment transport paths compared with literature [4]. Cumulative curves of fluvial deposits attain more and more lognormality with distance of transport, show two inflections, indicating breaks for rolling to saltation and saltation to suspension mode of transport. There is general fining of grain size downstream, Mz (φ ) increases. Majority of samples show moderate to poor sorting. The negative skewness in the upper stretch reflects addition of pebble sizes to the main sand fraction. Lower portion of river is getting moribund due its localized and arrested geomorphic setting and severe eutrophication with macroalgal blooms and marsh vegetation. Human interference caused modification to morphodynamics of the river channel. Systematic monitoring of its geomorphological and pollution status is suggested. [1] Frančišković-Bilinski (2007) Fres. Env. Bullet. 16, 561-575. [2] Frančišković-Bilinski (2007) J. Geochem. Explor. 88, 106-109. [3] Frančišković-Bilinski et al. (2005) Fres. Env. Bullet. 14, 282-290. [4] Mc Laren and Bowles (1985) J. Sed. Petrol. 55, 457-470.

Kupa River; channel processes; sedimentation; sediment transport

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