Although it has long been recognized that deposition along meandering rivers is not restricted to convex banks (i.e., point bars), the consensus is that sediment deposition on concave banks of channel bends mostly occurs when meander bends translate downstream because erosion-resistant barriers inhibit their lateral migration. Using a kinematic model of channel meandering and time lapse satellite imagery from the Mamoré River in Bolivia, we show that downstream translation and associated concave bank deposition are essential, autogenic parts of the meandering process, and resulting counter point bars are expected to be present whenever perturbations such as bend cutoffs and channel reoccupations create short bends with high curvatures. The implication is that zones of concave bank deposition with lower topography, finer-grained sediment, slack water, and riparian vegetation that differs from point bars are more common than previously considered.
Research Article|
March 12, 2021
Autogenic translation and counter point bar deposition in meandering rivers
Z. Sylvester
;
Z. Sylvester
1
Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, USA
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P.R. Durkin
;
P.R. Durkin
2
Department of Geological Sciences, University of Manitoba, Canada
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S.M. Hubbard
;
S.M. Hubbard
3
Department of Geoscience, University of Calgary, Canada
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D. Mohrig
D. Mohrig
4
Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, USA
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GSA Bulletin (2021)
Article history
received:
13 Jul 2020
rev-recd:
28 Oct 2020
accepted:
14 Jan 2021
first online:
12 Mar 2021
Citation
Z. Sylvester, P.R. Durkin, S.M. Hubbard, D. Mohrig; Autogenic translation and counter point bar deposition in meandering rivers. GSA Bulletin 2021; doi: https://doi.org/10.1130/B35829.1
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