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Sediment (Dis)Balance – a Significant River Management Issue

Author(s): Helmut Habersack, marlene haimann, Philipp Gmeiner, Sandor Baranya, Katarína Holubová, Florin Vartolomei

Linked Author(s): Helmut Habersack, marlene haimann, Philipp Gmeiner, Sándor Baranya

Keywords: Sediment transport; Sediment balance; Danube River; River morphology; Significant water management issue (SWMI);

Abstract: An increasing discrepancy between surplus and lack of sediments can be observed in many river basins. This leads to an increase of flood risks and a reduction of navigation possibilities, hydropower production and negatively impacts biodiversity. Thus, a main task is to improve sediment management as well as the river morphology. To close existing knowledge gaps quantitative sediment data have been collected all along the Danube River. A Sediment Balance was prepared, which explains the problems that arise with sediment discontinuity. The Danube River basin shows, in particular due to the disbalance of the sediment regime a heavily disturbed system. The input of suspended sediments to the Black Sea has e.g. been reduced from around 60 million tons per year to about 20 million tons per year, leading to increased coastal erosion. Moreover, long sections of the Danube River have been narrowed, channelized and disconnected from floodplains as well as morphologically degraded over the last 200 years. This has caused increased bottom shear stresses, and subsequently increases sediment transport capacities. As a consequence of both, longitudinal and lateral disturbances of the sediment supply and additional impacts of the channelization, the remaining free-flowing sections are subject to various forms of river bed degradation. Such degradation or river bed incision leads to a loss of instream structures in general, with a disappearance of gravel bars at the Upper Danube, and changes of sand bars at the Lower Danube. Possible answers to these problems are provided by a catalogue of measures.

DOI: https://doi.org/10.3850/38WC092019-1565

Year: 2019

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