Back‐calculation of bedload transport in steep channels with a numerical model |
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| Authors: | Michael Chiari Dieter Rickenmann |
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| Institution: | 1. University of Natural Resources and Life Sciences, Institute of Mountain Risk Engineering, Vienna, Austria;2. Swiss Federal Research Institute WSL, Birmensdorf, Switzerland |
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| Abstract: | In August 2005 severe flood events occurred in the Alps. A sediment routing model for steep torrent channel networks called SETRAC has been applied to six well‐documented case study streams with substantial sediment transport in Austria and Switzerland. For these streams information on the sediment budget along the main channel is available. Flood hydrographs were reconstructed based on precipitation data and stream gauges in neighbouring catchments. Different scenarios are modelled and discussed regarding sediment availability and the effect of armouring and macro‐roughness on sediment transport calculations. The simulation results show the importance of considering increased flow resistance for small relative flow depth when modelling bedload transport during high‐intensity flood events in torrents and mountain rivers. Without any correction of increased flow resistance using a reduced energy slope, the predicted bedload volumes are about a factor of 10 higher on average than the observed values. Simulation results were also used for a back‐calculation of macro‐roughness effects from bedload transport data, and compared with an independent estimate of flow resistance partitioning based on flow resistance data. Copyright © 2010 John Wiley & Sons, Ltd. |
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| Keywords: | bedload transport numerical modelling macro roughness stress partitioning steep gradient |
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