Long‐term morphodynamic evolution of a tidal embayment using a two‐dimensional, process‐based model

Wegen, Mick van der; Roelvink, Dano

doi:10.1029/2006jc003983

Cited by 178 publications

(218 citation statements)

References 37 publications

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“…Past long-term morphological modelling studies of estuaries that did not include mud showed channel bar patterns that are similar to those in nature (Hibma et al, 2003;Van der Wegen and Roelvink, 2008;Van der Wegen et al, 2008;. Cases in which boundaries eroded unhindered ( Van der Wegen et al, 2008) developed towards a state of decreasing morphodynamic activity as size and depth continued to increase and morphodynamic equilibrium was not reached.…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 83%

“…Models used either sand (e.g. Van der Wegen et al, 2008) or sand and mud without interactive transport (e.g. Sanford, 2008).…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

“…Cases in which boundaries eroded unhindered ( Van der Wegen et al, 2008) developed towards a state of decreasing morphodynamic activity as size and depth continued to increase and morphodynamic equilibrium was not reached. Most models, however, including the few models with mud, assumed prescribed planform shapes with nonerodible boundaries (Lanzoni and Seminara, 2002;Hibma et al, 2003;Van der Wegen and Roelvink, 2008; (Van Heuvel, 1991;Rijkswaterstaat, 2009) and (e) GeoTOP map (v1.3) of probability of clay occurrence in the top 50 cm of the bed (TNO, 2016). (f) Surface mud distribution along the Western Scheldt from the three datasets.…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

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Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

et al. 2017

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Abstract. Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive sediment. In this study we combine sand and mud transport processes and study their interaction effects on morphologically modelled estuaries on centennial to millennial timescales. The numerical modelling package Delft3D was applied in 2-DH starting from an idealised convergent estuary. The mixed sediment was modelled with an active layer and storage module with fluxes predicted by the Partheniades-Krone relations for mud and Engelund-Hansen for sand. The model was subjected to a range of idealised boundary conditions of tidal range, river discharge, waves and mud input. The model results show that mud is predominantly stored in mudflats on the side of the estuary. Marine mud supply only influences the mouth of the estuary, whereas fluvial mud is distributed along the whole estuary. Coastal waves stir up mud and remove the tendency to form muddy coastlines and the formation of mudflats in the downstream part of the estuary. Widening continues in estuaries with only sand, while mud supply leads to a narrower constant width and reduced channel and bar dynamics. This self-confinement eventually leads to a dynamic equilibrium in which lateral channel migration and mudflat expansion are balanced on average. However, for higher mud concentrations, higher discharge and low tidal amplitude, the estuary narrows and fills to become a tidal delta.

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Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 83%

“…Models used either sand (e.g. Van der Wegen et al, 2008) or sand and mud without interactive transport (e.g. Sanford, 2008).…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

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Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

et al. 2017

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“…Near the bed w = 0 m s −1 , and at the water surface w = dh/dt. A detailed description of the hydrodynamics and numerical scheme of Delft3D can be found in Lesser et al (2004), Van der Wegen and Roelvink (2008), and Deltares (2009). The bed level change in Delft3D is the result of sediment transport, bed slope effects, bank erosion, and mass conservation in the bed.…”

Section: Numerical Three-dimensional Modelmentioning

confidence: 99%

“…Inactive grid cells reactivated when the threshold water depth was exceeded, either by water level rise or by a simplified formulation of bank erosion. Here, "bank erosion" of a dry grid cell occurred when a neighboring wet grid cell eroded, where 50 % of the incision in the wet cell was applied to the dry cells (Van der Wegen and Roelvink, 2008). This prevents unnatural effects of accidentally emerged cells.…”

Section: Numerical Three-dimensional Modelmentioning

confidence: 99%

Network response to disturbances in large sand-bed braided rivers

2016

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Abstract. The reach-scale effects of human-induced disturbances on the channel network in large braided rivers are a challenge to understand and to predict. In this study, we simulated different types of disturbances in a large braided river to get insight into the propagation of disturbances through a braided channel network. The results showed that the disturbances initiate an instability that propagates in the downstream direction by means of alteration of water and sediment division at bifurcations. These adjustments of the bifurcations change the migration and shape of bars, with a feedback to the upstream bifurcation and alteration of the approaching flow to the downstream bifurcation. This way, the morphological effect of a disturbance amplifies in the downstream direction. Thus, the interplay of bifurcation instability and asymmetrical reshaping of bars was found to be essential for propagation of the effects of a disturbance. The study also demonstrated that the large-scale bar statistics are hardly affected.

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Processes governing decadal-scale depositional narrowing of the major tidal channel in San Pablo Bay, California, USA

Wegen

Jaffe

2014

J. Geophys. Res. Earth Surf.

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Bathymetric measurements show that a deep, subtidal channel in San Pablo Bay, California, has consistently narrowed during the past 150 years. This raises general questions on the seasonal and intertidal morphodynamic processes acting at the subtidal channel-shoal interface. The current work addresses these questions using a process-based morphodynamic model (Delft3D). Model results reveal considerable morphodynamic activity during a tidal cycle. Deposition on the channel margin is largest during flooding of the shoals. Erosion rates (mainly occuring during ebb) remain relatively small, so that net accretion occurs on much of the channel margin. A remarkable finding is that locally generated wind waves are responsible for shoal extension and depositional channel narrowing. High suspended sediment concentration (SSC) in the channel is a critical factor. Apart from sediment supply during high river flow, wind waves suspending sediment on the shoals cause high SSC levels in the channel at ebb. Sensitivity analysis shows that wind direction even determines the location of channel margin accretion. Fluvial sediment supply is another cause of high SSC in the channel. Density currents, 3-D circulation flows, sea level rise, or varied sediment characteristics only have a limited effect on the erosion and sedimentation patterns. A 30 year forecast shows that deeper shoals and decreasing fluvial sediment supply lower SSC levels in the channel, limit channel margin accretion, and even lead to net channel margin erosion in some areas. Channel shape thus remains subject to dynamic processes related to local variations in sediment supply, albeit to a more limited extent than in earlier decades.

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Long‐term morphodynamic evolution of a tidal embayment using a two‐dimensional, process‐based model

Cited by 178 publications

References 37 publications

Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

Network response to disturbances in large sand-bed braided rivers

Processes governing decadal-scale depositional narrowing of the major tidal channel in San Pablo Bay, California, USA

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