Bedload transport controls bedrock erosion under sediment-starved conditions
Fluvial bedrock incision constrains the pace of mountainous landscape evolution. Bedrock erosion processes have been described with incision models that are widely applied in river-reach and catchment-scale studies. However, so far no linked field data set at the process scale had been published tha...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-07-01
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| Series: | Earth Surface Dynamics |
| Online Access: | http://www.earth-surf-dynam.net/3/291/2015/esurf-3-291-2015.pdf |
| Summary: | Fluvial bedrock incision constrains the pace of mountainous landscape
evolution. Bedrock erosion processes have been described with incision models
that are widely applied in river-reach and catchment-scale studies. However,
so far no linked field data set at the process scale had been published that
permits the assessment of model plausibility and accuracy. Here, we evaluate
the predictive power of various incision models using independent data on
hydraulics, bedload transport and erosion recorded on an artificial bedrock
slab installed in a steep bedrock stream section for a single bedload
transport event. The influence of transported bedload on the erosion rate
(the "tools effect") is shown to be dominant, while other sediment effects
are of minor importance. Hence, a simple temporally distributed incision
model, in which erosion rate is proportional to bedload transport rate, is
proposed for transient local studies under detachment-limited conditions.
This model can be site-calibrated with temporally lumped bedload and erosion
data and its applicability can be assessed by visual inspection of the study
site. For the event at hand, basic discharge-based models, such as
derivatives of the stream power model family, are adequate to reproduce the
overall trend of the observed erosion rate. This may be relevant for
long-term studies of landscape evolution without specific interest in
transient local behavior. However, it remains to be seen whether the same
model calibration can reliably predict erosion in future events. |
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| ISSN: | 2196-6311 2196-632X |