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

Milan, DJ, Heritage, G, Entwistle, NS and Tooth, S 2017, 'Morphodynamic simulation of sediment deposition patterns on a recently stripped bedrock anastomosed channel' , Proceedings of the International Association of Hydrological Sciences (PIAHS), 94 , pp. 1-6.

[img]
Preview
PDF - Published Version
Available under License Creative Commons Attribution 4.0.

Download (1MB) | Preview

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.

Item Type: Article
Schools: Schools > School of Environment and Life Sciences > Ecosystems and Environment Research Centre
Journal or Publication Title: Proceedings of the International Association of Hydrological Sciences (PIAHS)
Publisher: International Association of Hydrological Sciences (IAHS)
Depositing User: NS Entwistle
Date Deposited: 08 Sep 2017 08:16
Last Modified: 08 Sep 2017 14:54
URI: http://usir.salford.ac.uk/id/eprint/43705

Actions (login required)

Edit record (repository staff only) Edit record (repository staff only)

Downloads

Downloads per month over past year