Journal metrics

Journal metrics

  • CiteScore value: indexed CiteScore
    indexed
  • SNIP value: indexed SNIP
    indexed
  • SJR value: indexed SJR
    indexed
  • IPP value: indexed IPP
    indexed
Volume 377
Proc. IAHS, 377, 51-56, 2018
https://doi.org/10.5194/piahs-377-51-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Proc. IAHS, 377, 51-56, 2018
https://doi.org/10.5194/piahs-377-51-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

  16 Apr 2018

16 Apr 2018

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

David Milan1, George Heritage2, Neil Entwistle3, and Stephen Tooth4 David Milan et al.
  • 1School of Environmental Science, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
  • 2AECOM, Exchange Court, 1 Dale Street, Liverpool, L2 2ET, UK
  • 3School of Environment and Life Sciences, University of Salford, Salford, M5 4WT, UK
  • 4Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK

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 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.

Publications Copernicus
Download
Short summary
We present 2D morphodynamic simulations of hydraulics and sediment deposition patterns over an exposed bedrock anastomosed pavement. Alluvial barforms appear to be initiated through sediment deposition in bedrock topographic lows. It is likely that vegetation establishment in these depositional loci increases the cohesive strength of the deposited sediment and captures additional sediment and propagules, eventually leading to greatest thicknesses of alluvium positioned over the bedrock lows.
We present 2D morphodynamic simulations of hydraulics and sediment deposition patterns over an...
Citation
Share