Network response to disturbances in large sand-bed braided rivers

Schuurman, F.; Kleinhans, Maarten G.; Middelkoop, H.

doi:10.5194/esurf-4-25-2016

Cited by 27 publications

(22 citation statements)

References 55 publications

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“…The Delft3D model (version FLOW 6.01.07.3574, 2 April 2014) has been applied in many scientific projects to compute hydrodynamics, sediment transport, and morphological changes (Crosato & Saleh, ; Deltares, ; Roelvink, ; Schuurman et al, ; Schuurman, Kleinhans, et al, ; Van der Wegen & Roelvink, ; Van Dijk et al, ). In this study, we applied a 2‐D depth‐averaged flow field, which meant that the effect of helical flow driven by flow curvature on bed shear‐stress direction was parametrized (Baar, Albernaz, et al, ; Baar, De Smit, et al, ; Schuurman et al, ).…”

Section: Model Description and Methodsmentioning

confidence: 99%

“…The nonlinear dynamics of sediment transport limits the potential to record and pass on physical environmental disturbances and perturbations (Jerolmack & Paola, ). Such disturbances for fluvial systems have been subdivided into four categories (Schuurman, Kleinhans, et al, ): (i) external temporal perturbation of the upstream inflow, (ii) external spatial perturbation, for example, along the outer channel banks, (iii) external perturbation at the downstream boundary, and (iv) internal perturbations within the reach. Shoal margin collapses fall within the fourth group of disturbances as sediment is eroded from the shoal within the estuary system.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Shoal Margin Collapses on the Morphodynamics of a Sandy Estuary

et al. 2019

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Shoal margin collapses of several million cubic meters have occurred in the Western Scheldt estuary, the Netherlands, on average five times a year over the last decades. While these collapses involve significant volumes of material, their effect on the channel‐shoal morphology is unknown. We hypothesize that collapses dynamicize the channel‐shoal interactions, which could impact the ecological functioning, flood safety, and navigation in the estuary. The objective is to investigate how locations, probability, type, and volume of shoal margin collapse affect the channel‐shoal dynamics. We implemented an empirically validated parameterization for shoal margin collapses and tested its effect on simulated estuary morphological development in a Delft3D schematization of the Western Scheldt. Three sets of scenarios were analyzed for near‐field and far‐field effects on flow pattern and channel‐shoal morphology: (1) an observed shoal margin collapse of 2014, (2) initial large collapses on 10 locations, and (3) continuous collapses predicted by our novel probabilistic model over a time span of decades. Results show that a single shoal margin collapse only affects the local dynamics in the longitudinal flow direction and dampen out within a year for typical volumes, whereas larger disturbances that reach the seaward or landward sill at tidal channel junctions grow. The direction of the strongest tidally averaged flow determined the redistribution of the collapsed sediment. We conclude that adding the process of shoal margin collapses increases the channel‐shoal interactions and that in intensively dredged estuaries shoal margins oversteepen, amplifying the number of collapses, but because of dredging the natural morphological response is interrupted.

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Section: Model Description and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Shoal Margin Collapses on the Morphodynamics of a Sandy Estuary

et al. 2019

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“…During higher discharges with overbank flow, the channel branches in braided rivers interact with the floodplains, among others through bank erosion and floodplain formation by aggradation and vegetation growth on floodplain-attached bars (Crosato and Saleh, 2010;Vesipa et al, 2015;Schuurman et al, 2016a;Lewin et al, 2016). The balance between bank erosion and floodplain accretion determines the channel width-depth ratio and consequently the braiding intensity (e.g.…”

Section: Introductionmentioning

confidence: 99%

Response of braiding channel morphodynamics to peak discharge changes in the Upper Yellow River

Schuurman

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et al. 2018

Earth Surf Processes Landf

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The braiding intensity and dynamics in large braiding rivers are well known to depend on peak discharges, but the response in braiding and channel–floodplain transformations to changes in discharge regime are poorly known. This modelling study addresses the morphodynamic effects of increasing annual peak discharges in braiding rivers. The study site is a braiding reach of the Upper Yellow River. We estimated the effects on the larger‐scale channel pattern, and on the smaller‐scale bars, channel branches and floodplains. Furthermore, we determined the sensitivity of the channel pattern to model input parameters. The results showed that the dominant effect of a higher peak discharge is the development of chute channels on the floodplains, formed by connecting head‐cut channels and avulsive channels. Widening of the main channel by bank erosion was found to be less dominant. In addition, sedimentation on the bars and floodplains increased with increasing peak discharge. The model results also showed that the modelled channel pattern is especially sensitive to parametrization of the bed slope effect, whereas the effect of median grain size was found to be relatively small. Copyright © 2018 John Wiley & Sons, Ltd.

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“…Attempts have been done to reconstruct the characteristics of palepchannel by understanding the planform migration structure of channel and evolution of dynamic geomorphic process (Ielpi and Ghinassi, 2014;Ghinassi et al, 2014;Wu et al, 2016). Although researches about the morphology and migration of meandering channels are attempted (Schuurman et al, 2016;Rousseau et al, 2016), it still remains poorly undefined how to account for the processes of migration structures.…”

Section: Introductionmentioning

confidence: 99%