Medium-term 2DH coastal area modelling

Vriend, H.J. de; Zyserman, Julio A.; Nicholson, John; Roelvink, Dano; Pechon, Philippe; Southgate, H.N.

doi:10.1016/0378-3839(93)90050-i

Cited by 187 publications

(83 citation statements)

References 29 publications

(32 reference statements)

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“…Coastal morphological area models had been developed since the early 1980s (De Vriend et al, 1993;Nicholson et al, 1997). So far, there are some robust and flexible models, such as Delft3D (Deltares, 2014), XBeach (Roelvink et al, 2009;Roelvink et al, 2018), Mike (Pietrzak et al, 2002), Telemac (Villaret, 2010;Villaret et al, 2013), ECOMSED (Blumberg, 2002), ADCIRC (Luettich and Westerink, 2004), ROMS (Warner et al, 2008), Wallingford, COHERENS (Luyten et al, 2006), etc.…”

Section: Coastal Area Models: 2dh and 3d Modelsmentioning

confidence: 99%

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Zuo¹

2018

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Although all care is taken to ensure integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers, the author nor IHE Delft for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein. A pdf version of this work will be made available as Open Access via http://repository.tudelft.nl/ihe. This version is licensed under the Creative Commons To my family AbstractThe evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. Inspired by the Caofeidian sea area in Bohai Bay, China, this study aims to better understand silty sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL), and to improve our modelling approaches in predicting estuarine and coastal sediment transport.Field observations were carried out in northwestern Caofeidian sea area of Bohai Bay and field data were collected on several other silt-dominated coasts. Analysis shows that silt-dominated sediments are sensitive to flow dynamics: the suspended sediment concentrations (SSCs) increase rapidly under strong flow dynamics (i.e., waves or strong tidal currents which can stir up sediments), and high concentrations cause heavy sudden back siltation in navigation channels. In the following, details of silty sediment transport are studied, focusing on the BBL and high concentration layer (HCL).From laboratory experiments and theoretical analysis, an expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. The Shields number was revised by adding the cohesive force and additional static pressure, leading to an extended Shields curve.To study the HCL, a process based 1DV model was developed for flow-sediment dynamics near the bed in combined wave-current conditions. Based on the physical processes, special approaches for sediment movement were introduced, including approaches for different bed forms (rippled bed and 'flat-bed'), hindered settling, stratification effects, mobile bed effects, reference concentration and critical shear stress. The HCL was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the sediment concentration in the HCL. The results show that the HCL is affected by both flow dynamics and bed forms; the thickness of the HCL is about twice the height of the wave boundary layer; bed forms determine the shape of the concentration profile near the bottom, and flow dynamics determine the magnitude. For finer sediment, stratification effects and mobile bed effects impact the sediment concentration greatly.Finally, based on the 1DV model, the formulations of the mean sediment concentration profile of silty sediments were studied. By solving the time-averaged diffusion equation for SSC and considering the effects of bed forms, stratification and hindered settling, expressions for time-averaged SSC profile...

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Section: Coastal Area Models: 2dh and 3d Modelsmentioning

confidence: 99%

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Zuo¹

2018

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“…Considering well-developed subcritical and supercritical conditions, hydro-morphodynamics can be uncoupled (De Vriend et al, 1993;Juez et al, 2013). Therefore, the equations used for the simplified 1-D model are reduced to the sediment continuity equation along the stream (Eq.…”

Section: Constitutive Equationsmentioning

confidence: 99%

Long-term Morphodynamics of a Schematic River Analysed with a Zero-dimensional, Two-reach, Two-grainsize Model

Franzoia

Nones

Silvio

2017

Preprint

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Abstract. At the basin scale, neglecting localized deviations caused by geological constraints like knick-points, alluvial 10 rivers commonly exhibit a concave profile and a progressive sediment fining in the downstream direction. Although this configuration is, perforce, not in equilibrium, yet it usually shows a quasi-stationary behaviour at the very long (historical and geological) time-scale.A zero-dimensional, two-reach, two-grainsize hydro-morphological model is presented and applied to a schematic river. The description of the processes involved is done assuming several reasonable and verified simplifications, giving reason of the 15 extremely slow evolution of many alluvial rivers and providing a quantitative approach to evaluate their 'response time'.Different from previous analytical formulations, the response time appears here to be affected, among others, by the granulometry of the sediment input. Applications of the model to different geometries demonstrate that the present riverine morphology at the basin scale will persist practically stationary for extremely long periods of time (centuries and even millennia), if the climatic forcing remain 20 unchanged and no anthropogenic perturbations are introduced in the system.

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“…The local sediment transport is first calculated by wave and current sub-models, and the bed form evolution is then computed based on the conservation of sediment and its continual redistribution in time. In the last twenty years, two dimensional depth-averaged coastal morphological models have been developed, and these models have been applied in the short-term (hours to days) and medium-term (weeks, months to years) (Coeffe' and Pe'chon, 1982;Yamaguchi and Nishioka, 1984;Watanabe, 1986;Anderson et al, 1991;Wang et al, 1992;de Vriend et al, 1993b;Sato et al, 1995;Nicholson et al, 1997) 2. Modelling coastal morphological evolution…”

Section: The Main Concern Of Coastal Morphological Models In Present mentioning

confidence: 99%

Coastal Morphological Modeling

Chiang¹,

Hsiao²

2011

Sediment Transport in Aquatic Environments

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The coastal zone is the area where the action of waves and wave-driven-currents on the seabed is very intense, and where the bed level and sediment are almost always in motion. If the mainly seasonal climate changes, the wind and wave conditions will also change. A new waves and wave-driven-currents conditions will change the rate of sediment transport and the beach topography. Natural beaches are significant characterized by an annual cycle of seasonal erosion and accretion. In other words, natural beaches are generally in dynamic equilibrium from the balance of sediment transport budge for specific area on the beach. We can utilize the conservation law of sediment transport to describe the coastal morphodynamic evolution. It is the same way to predict beach evolution due to changes in wave conditions or caused by coastal structures. Therefore, we can utilize numerical models to predict the change of bottom topography from the spatial distribution of the alongshore and offshore sediment transport rates in real coastal area. Coastal morphological models are indispensable and powerful tools that allow harbour and hydraulic engineers to predict nearshore topography, to analyze the impact of coastal structures, and to verify the planning and design of harbours and coastal defences. Morphological models are based on various sub-models for waves, tidal currents, nearshore currents, and sediment transport, coupled with the sediment transport model. The sediment transport model solves the sediment conservation equation to calculate bed-level evolution. The local sediment transport is first calculated by wave and current sub-models, and the bed form evolution is then computed based on the conservation of sediment and its continual redistribution in time. The aim of this chapter is to describe the theories, techniques, applications and robust algorithms for computing bed level change which is flexible enough to handle the nonlinearity present in the sediment conservation equations describing bed evolution in a complex coastal area. Classification of prediction methods for morphological evolutionThe changes of coastal topography were the complex and irreversible morphodynamic processes, influenced by local bathymetry, weather, wave, tide, and coastal structures, etc. The technology of prediction morphological evolution caused by coastal structures or varied with monsoon, typhoon, and climate changes, etc. is needed. In order to predict morphological evolutions, the experience analysis with many survey data in similar cases and the results of hydraulic model tests are considered in the past.

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Medium-term 2DH coastal area modelling

Cited by 187 publications

References 29 publications

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Long-term Morphodynamics of a Schematic River Analysed with a Zero-dimensional, Two-reach, Two-grainsize Model

Coastal Morphological Modeling

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