A mass‐conservative staggered immersed boundary model for solving the shallow water equations on complex geometries

Canestrelli, Alberto; Spruyt, Aukje; Jagers, Bert; Slingerland, Rudy; Borsboom, Mart

doi:10.1002/fld.4180

Cited by 10 publications

(12 citation statements)

References 34 publications

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“…In particular, we find this approach appropriate for long‐term simulations, in which the details of short‐term erosion are not essential. While this approach is appropriate for wave driven erosion, given that the wave field does not strongly depend on grid discretization, more refined approaches are needed to model bank erosion driven by tidal and riverine currents, which are highly sensitive to grid discretization [ Canestrelli et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…During the time step Δ t i , the k th edge of a marsh cell should retreat by the amount

Ψ_{k} = \int_{{Δ t}_{i}}^{} E_{w}^{k} d t,

where

E_{w}^{k}

is the erosion rate at edge k . Because the value

Ψ_{k}

is several orders of magnitude smaller than the size of a cell, partial cells should be implemented to keep track of this erosion, a process that highly complicates the flow calculation [ Canestrelli et al ., ]. In order to simplify the computation, a probabilistic approach is undertaken (Figure ).…”

Section: Methodsmentioning

confidence: 99%

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Long‐term morphodynamics of muddy backbarrier basins: Fill in or empty out?

Mariotti

Canestrelli²

2017

Water Resources Research

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The long‐term (3000 years) morphodynamics of an idealized muddy backbarrier tidal basins is studied using a shallow‐water hydrodynamics and wind‐wave model (Deltf3D‐FLOW‐WAVE), modified to include fully coupled marsh organogenic accretion, biostabilization, drag increase, and wave‐induced marsh edge erosion. The latter process is implemented with a novel probabilistic algorithm. Starting from an initially empty basin with a uniform bed slope, a network of channels incise the mudflat, sediment is released, and marshes establish at the basin landward margin. If enough mud is supplied to the basin from the shelf, marsh progradation counteracts marsh edge erosion and marshes expand. Marsh expansion does not completely fill the basin but leaves open a few km‐wide channels, large enough for waves to resuspend sediment. Starting from a basin (almost) filled with marshes, a drop in the external mud supply or an increase in the rate of relative sea level rise causes the basin to empty out by marsh edge erosion, while the marsh platform, aided by reworking of the sediment released by marsh retreat and mudflat deepening, keeps pace even with fast rates (10 mm/yr) of relative sea level rise. Even if the marsh does not drown, the marsh retreats faster if the rate of sea level rise increases, because more sediment is sequestered to fill the newly created accommodation space and is thus not available for marsh progradation. This study suggests that prediction of marsh erosion requires a basin‐scale sediment budget, and that edge erosion, not platform drowning, is likely to dominate marsh loss.

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Section: Discussionmentioning

confidence: 99%

“…During the time step Δ t i , the k th edge of a marsh cell should retreat by the amount

Ψ_{k} = \int_{{Δ t}_{i}}^{} E_{w}^{k} d t,

where

E_{w}^{k}

is the erosion rate at edge k . Because the value

Ψ_{k}

Section: Methodsmentioning

confidence: 99%

Long‐term morphodynamics of muddy backbarrier basins: Fill in or empty out?

Mariotti

Canestrelli²

2017

Water Resources Research

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“…To study the role of disturbance on the morphology of estuaries, the most control is offered by numerical models. Numerical morphodynamic models are useful tools, but interaction with bank erosion processes introduces complications (Canestrelli et al, ). The forecasting of these interactions is not commonly addressed due to the complexity of coupling short‐term geotechnical processes with long‐term morphological development.…”

Section: Introductionmentioning

confidence: 99%

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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“…Attempts to blend the fixed‐mesh and moving‐mesh approaches have been recently undertaken by Canestrelli et al . [] and Langendoen et al . [].…”

Section: Introductionmentioning

confidence: 99%

“…The strategy of Canestrelli et al . [], presently available only for purely hydrodynamic modeling, represents the bank by an immersed moving boundary within a fixed‐mesh model. The approach of Langendoen et al .…”

Section: Introductionmentioning

confidence: 99%

A framework for the analysis of noncohesive bank erosion algorithms in morphodynamic modeling

Stecca

Measures

Hicks

2017

Water Resources Research

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In this paper, we analyze the performance of several noncohesive bank erosion algorithms to be embedded into two‐dimensional models for river hydromorphodynamics on nonmoving meshes. To avoid the complexity of analyzing two‐dimensional model results arising from the nonlinear interaction between flow, fluvial transport, and bank erosion, we develop a simplified framework. In detail, we reduce the two‐dimensional morphodynamic model to a cross‐sectional model under the assumption of longitudinal morphodynamic equilibrium, and apply bank erosion algorithms therein. To build candidate bank erosion models, we break down bank erosion algorithms into three modeling steps: identification of the bank, computation of sediment fluxes due to bank erosion, and bank updating. Different potential models are created by choosing different options for each step. We assess model performance against surveyed bank erosion over a flood event in the transitional Selwyn River, New Zealand. This study is preliminary to implementation of bank erosion in a fully two‐dimensional setting, to model braided planform dynamics.

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A mass‐conservative staggered immersed boundary model for solving the shallow water equations on complex geometries

Cited by 10 publications

References 34 publications

Long‐term morphodynamics of muddy backbarrier basins: Fill in or empty out?

Long‐term morphodynamics of muddy backbarrier basins: Fill in or empty out?

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

A framework for the analysis of noncohesive bank erosion algorithms in morphodynamic modeling

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