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| Titel |
Fluvial bedrock erosion by sediment in suspension couples hillslope processes and channel evolution |
| VerfasserIn |
D. L. Egholm, M. F. Knudsen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070126
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| Zusammenfassung |
| Computational landscape evolution models that simulate long-term denudation of mountain ranges are often based on the stream-power model for detachment-limited fluvial erosion. When integrated with models for long-term hillslope erosion and sediment transport, the stream-power model predicts realistic landscapes with concave steady-state river profiles.
However, the rate of stream-power erosion depends solely on the amount of surface runoff (precipitation) and the channel bed slope. This does not agree well with global estimates of erosion rates based on in-situ produced cosmogenic nuclides, which link high erosion rates to tectonic activity rather than high precipitation rates and topographic relief (von Blankenburg, 2005).
As an alternative to the stream-power model, Sklar & Dietrich (2004) have proposed a saltation-abrasion model for river incision by saltating bed load. In the saltation-abrasion model, the sediments in suspension erode the riverbed when grains collide with the bedrock. In this presentation, we show with three-dimensional landscape evolution models that river incision by saltating bed load depends critically on sediment delivery from the un-channelized hillslopes. Such sediment delivery is achieved through landslides in tectonically active regions. The saltation-abrasion model therefore pinpoints the critical processes that potentially explain the observed pattern of global erosion rates that highlight the importance of tectonic activity.
References
von Blankenburg, F., 2005. The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment. Earth and Planetary Science Letters, 237, p. 462-497.
Sklar, L. S. & Dietrich, W. E. , 2004. A mechanistic model for river incision into bedrock by saltating bed load. Water Resources Research, 40, W06301. |
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