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| Titel |
Testing new roughness approaches for calculating bedload transport rates in steep mountain streams |
| VerfasserIn |
M. Nitsche, A. Badoux, J. M. Turowski, D. Rickenmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025250
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| Zusammenfassung |
| Currently used methods for predicting bedload transport do not appropriately represent
typical roughness elements of small, steep mountain streams, like step-pool sequences, large
boulders or woody debris. Besides sediment supply, flow resistance due to such form
roughness elements appears to be an important control on bedload transport rates in small,
steep mountain streams.
Recently, new approaches based on laboratory experiments were proposed to assess flow
resistance due to form roughness. They quantify the effects of generalized models of
roughness elements to flow resistance. Furthermore, several empirically derived formulae to
calculate bedload transport rates including a respective roughness parameter have
been published. None of these approaches has been systematically tested with field
observations.
We review these approaches and analyze their applicability for natural streams.
For this purpose, we measured the required roughness parameters for seven Swiss
mountain streams, with local channel gradients ranging from 1.5 to 16.5 %, and
catchment areas from 12 to 43 km2. We calculated flow resistance and bedload
transport for sediment transport events in 2000 and 2005, for which information on
discharge and transported bedload volumes are available. By comparing calculated
and observed data of bedload transport we identified whether and in which range
the examined approaches are suitable for application in natural stream conditions. |
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