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

Milan, David; Heritage, George; Entwistle, Neil; Tooth, Stephen

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Dr David Milan D.Milan@hull.ac.uk
Senior Lecturer in Physical Geography; Programme Director BSc Physical Geography/Geography; Employability Officer

George Heritage

Neil Entwistle

Stephen 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 2D morphodynamic simulations of hydraulics and sediment deposition patterns over an exposed bedrock anastomosed pavement. We examine the assumptions underlying 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 intermediate 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 deposits 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.

Journal Article Type Conference Paper
Publication Date Apr 16, 2018
Journal Proceedings of the International Association of Hydrological Sciences
Print ISSN 2199-8981
Electronic ISSN 2199-899X
Publisher Copernicus Publications
Peer Reviewed Peer Reviewed
Volume 377
Pages 51-56
APA6 Citation Milan, D., Heritage, G., Entwistle, N., & Tooth, S. (2018). Morphodynamic simulation of sediment deposition patterns on a recently stripped bedrock anastomosed channel. Proceedings of the International Association of Hydrological Sciences, 377, 51-56. https://doi.org/10.5194/piahs-377-51-2018
DOI https://doi.org/10.5194/piahs-377-51-2018
Keywords LiDAR, anastomosed, dryland river, 2D Morphodynamic simulation, sediment transport
Publisher URL https://www.proc-iahs.net/377/51/2018/
Additional Information This is the authors' accepted manuscript of an article which has been accepted for future publication in: Proceedings of the International Association of Hydrological Sciences

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Copyright Statement
© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License.



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