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PRE-Dimensioning of a Mean Annual Discharge Channel in Terms of Restoration of Freshwater Pearl Mussel Habitats in Granite and Gneiss Basins

Author(s): Flodl Peter; Hauer Christoph

Linked Author(s): Christoph Hauer

Keywords: No Keywords

Abstract: Multiple stressors on river ecosystems lead to a loss of suitable habitats for the freshwater pearl mussel (Margaritifera Margaritifera) and its host fish brown trout. The anthropogenic alteration of river morphology and the increase of sediment supply notably contribute to the population decline in Austrian rivers (Central Europe). A successful conservation requires a science proofed concept to deal with the complex life cycle of FWPM populations with its different needs in terms of substrate conditions and riverbed stability. However, for habitat restoration projects of Austrian FWPM rivers there is a lack of regime studies for channel predimensioning. In particular, concepts, which intend to prevent the increasing siltation and the related degradation of habitats, are missing. Based on field survey in FWPM rivers one-dimensional hydrodynamic-numerical models were used for both, (1) testing of well-known equations for prediction in regime channels and (2) for trend analysis with power-functions. Although some of the published equations are suitable for the establishment of long term channel width during high flows (e. g. one-year-flood). Most of the investigated river stretches, however, show stabilized lateral sediment depositions in the channel corresponding to the water surface elevation of mean-water flow. The derived equation from the trend analysis shows a good correlation between river width and mean flow which already transports sand loads in the rivers. Thus, results of this study demonstrate that the mean annual discharge is important in terms of long term channel forming in FWPM rivers and this approach should be further used for pre-dimensioning.


Year: 2018

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