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Morphodynamic simulation of sediment deposition
patterns on a recently stripped bedrock anastomosed
channel

Milan, DJ; Heritage, G; Entwistle, NS; Tooth, S

Morphodynamic simulation of sediment deposition
patterns on a recently stripped bedrock anastomosed
channel Thumbnail


Authors

DJ Milan

G Heritage

S Tooth



Abstract

Some mixed bedrock-alluvial dryland rivers are known to undergo cycles of alluvial building during low flow periods, punctuated by stripping events during rare high magnitude flows. We focus on the Olifants River, Kruger National Park, South Africa, and present 2-D morphodynamic simulations of hydraulics and sed-iment deposition patterns over an exposed bedrock anastomosed pavement. We examine the assumptions un-derlying a previous conceptual model, namely that sedimentation occurs preferentially on bedrock highs. Our modelling results and local field observations in fact show that sediment thicknesses are greater over bedrock lows, suggesting these are the key loci for deposition, barform initiation and island building. During peak flows, velocities in the topographic lows tend to be lower than in intermediate topographic areas. It is likely that inter-mediate topographic areas supply sediment to the topographic lows at this flow stage, which is then deposited in the lows on the falling limb of the hydrograph as velocities reduce. Subsequent vegetation establishment on de-posits in the topographic lows is likely to play a key role in additional sedimentation and vegetation succession, both through increasing the cohesive strength of alluvial units and by capturing new sediments and propagules.

Citation

channel. Proceedings of the International Association of Hydrological Sciences, 377, 51-56. https://doi.org/10.5194/piahs-377-51-2018

Journal Article Type Article
Acceptance Date Aug 16, 2017
Online Publication Date Apr 16, 2018
Publication Date Apr 16, 2018
Deposit Date Sep 8, 2017
Publicly Available Date Sep 8, 2017
Journal Proceedings of the International Association of Hydrological Sciences (PIAHS)
Print ISSN 2199-8981
Electronic ISSN 2199-899X
Publisher Copernicus Publications
Volume 377
Pages 51-56
DOI https://doi.org/10.5194/piahs-377-51-2018
Publisher URL https://doi.org/10.5194/piahs-377-51-2018
Related Public URLs https://www.proceedings-iahs.net/home.html

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