Development of a mud transport model for the Scheldt estuary (original) (raw)
Related papers
Influence of harbour construction on mud accumulation in the Scheldt estuary
Aquatic Ecosystem Health & Management, 2007
The bottom sediments of the turbidity maximum area of the Scheldt estuary were mapped in 1999 using echo sounding, sidescan sonar and grain-size analyses of bottom sediments. Four sediment types, sand, muddy sand, sandy mud and mud were recognised. Mud, with very little sand, occurs mainly in the access channels to the sluices giving access to the harbour docks of Antwerp. The sediments of the main channel have a sandier texture. One might conclude that the total mud stock in the middle estuary has increased, both between 1964–1986 and 1986–1999, but on the contrary the mud supply from the river, the mud stock in the river channel and the mud supply to the lower estuary have all decreased. The increase in the mud stock in the area as a whole was completely at the expense of mud deposition in the access channels to the sluice gates giving access to the harbour of Antwerp. The mud stock in the river channel decreased over the years because of a decreasing mud supply from the river. Th...
Mixed-sediment transport modelling in Scheldt estuary with a physics-based bottom friction law
Ocean Dynamics, 2015
In this study, the main object is to investigate the performance of a few new physics-based process models by implementation into a numerical model for the simulation of the flow and morphodynamics in the Western Scheldt estuary. In order to deal with the complexity within the research domain, and improve the prediction accuracy, a 2D depthaveraged model has been set up as realistic as possible, i.e. including two-way hydrodynamic-sediment transport coupling, mixed sand-mud sediment transport (bedload transport as well as suspended load in the water column) and a dynamic non-uniform bed composition. A newly developed bottom friction law, based on a generalised mixing-length (GML) theory, is implemented, with which the new bed shear stress closure is constructed as the superposition of the turbulent and the laminar contribution. It allows the simulation of all turbulence conditions (fully developed turbulence, from hydraulic rough to hydraulic smooth, transient and laminar), and the drying and wetting of intertidal flats can now be modelled without specifying an inundation threshold. The benefit is that intertidal morphodynamics can now be modelled with great detail for the first time. Erosion and deposition in these areas can now be estimated with much higher accuracy, as well as their contribution to the overall net fluxes. Furthermore, Krone's deposition law has been adapted to sand-mud mixtures, and the critical stresses for deposition are computed from suspension capacity theory, instead of being tuned. The model has been calibrated and results show considerable differences in sediment fluxes, compared to a traditional approach and the analysis also reveals that the concentration effects play a very important role. The new bottom friction law with concentration effects can considerably alter the total sediment flux in the estuary not only in terms of magnitude but also in terms of erosion and deposition patterns.
Longshore Transport and Sedimentation in a Navigation Channel at Blankenberge (Belgium)
Coastal Engineering Proceedings, 2012
The harbour of Blankenberge in Belgium experiences strong sedimentation in its entrance channel requiring frequent dredging. In order to investigate under which conditions this sedimentation is the most pronounced, the instationary coastal model XBeach is used. This paper presents results of long-term morphology modelling of channel sedimentation after applying a specific methodology for input reduction. A reduced time series representative of the annual wind-wave climate is run in combination with a representative tide and a constant morphological acceleration factor (morfac) to cover one year of erosion-sedimentation. While this approach does come with side effects, it has the important advantage to be easy to implement and to preserve part of the climate history compared to other approaches such as MorMerge and a time-varying morfac approach (described in the paper). With this approach and default settings, XBeach is shown to reproduce both qualitatively and quantitatively well t...
Continental Shelf …, 2010
Following the recent completion of the Deurganckdok (DGD) tidal dock in the Port of Antwerpen, Belgium, the Flemish government commissioned a programme of field surveys with the aim to identify potential changes in sediment properties. A significant feature of the Lower Sea Scheldt (LSS) is the presence of a turbidity maximum zone (TMZ) with depth-averaged suspended particulate matter (SPM) concentrations between 50 and 500 mg l À 1 . This paper highlights aspects of the findings of the suspended sediment properties measured during HCBS1 (conducted in February 2005 prior to DGD construction) and HCBS2 (September 2006 when the dock was open and in operation) surveys, including data comparison.
Integrated Modelling of the Belgian Coastal Zone
Estuarine, Coastal and Shelf Science, 2001
The management of the water resources in coastal or delta plains asks for an integrated modelling of the water system at a regional scale. In the SALMON project, detailed descriptions of the groundwater, river and marine domains are provided by coupling appropriate numerical models of these different subsystems. The application of this threefold model to the Scheldt and Belgian Coastal Zone reveals a marked river plume extending along the Belgian Coast with strong offshore gradients. This plume cannot be explained by the Eulerian residual transport velocity field but requires Lagrangian aspects to be taken into account. The computation of the age of this water mass shows that the different parts of the coastal zone are influenced by a discharge in the Grote Schijn River after a delay that varies between a few days (for the marine part of the estuary) to about 100 days (for the centre of the residual gyre). The computation shows also that the groundwater around Antwerp can also be contaminated by a pollution in the river but the resulting mass loss from the river does not lead to a significant reduction of the flux to the coastal zone.
Modeling the morphodynamics of the mouth of the Scheldt estuary
2015
Recent research on the Scheldt estuary mainly focused on the Western Scheldt. There is now a renewed interest in the mouth of the estuary as the Flemish government explores the feasibility of large-scale morphological interventions in that area. This paper describes the ongoing development of a process-based numerical model (Delft3D) of the Scheldt estuary. The so-called Delft3D-NeVla model computes morphodynamics forced by waves, tide, wind and river discharge, and affected by sediment dredging and dumping to maintain navigation channels at the desired depth. After further calibration and validation, the Delft3D-NeVla model will become an important tool to understand and predict the morphodynamics of the mouth of the estuary due to natural processes and large-scale morphological interventions such as relocation of navigation channels.
International Journal of Sediment Research, 2020
In order to optimize ship navigation in the macrotidal Gironde Estuary, a recent project funded by the port of Bordeaux aims at better understand and forecast hydrodynamic and fine sediment transport within the estuary. In the framework of this project, a twodimensional hydro-sedimentary model is built. The model includes hydrodynamic forcings, mixed-sediment transport, and consolidation processes. The harmonic analysis of the astronomical tides reveals a strong distortion of the tidal wave inducing the growth of overtide constituents and the non-significant effect of tide-surge interactions in annual-scale prediction. Depending on hydrological conditions, river discharge can considerably alter the model accuracy due to the migration of the turbidity maximum zone modifying the bottom roughness. Comparison with measurements shows the ability of the model to reproduce suspended-sediment concentrations in the central Estuary. Sensitivity of the model to sediment features has also been discussed in regard of suspended-sediment concentrations and fluid mud deposits. The model will be further coupled with ship squat and morphodynamic models. p { margin-bottom: 0.25 cm; line-height: 115%; }
Diagnosis of the sediment transport in the Belgian Coastal Zone
Estuarine, Coastal and Shelf Science, 2007
Estimating the age of particles in marine environment constitutes an invaluable tool to understand the interactions between complex flows and sediment dynamics, particularly in highly energetic coastal areas such as the Belgian Coastal Zone (Southern Bight in the North Sea). To this end, the Constituent Age and Residence time Theory e CART e introduced by Delhez, E.J.M., Campin, J.-M., Hirst, A.C., Deleersnijder, E. [1999a. Toward a general theory of the age in ocean modelling. Ocean Modelling 1, 17e27] for passive water constituents is extended to describe the sediment dynamics. It is then used in combination with a three-dimensional coupled hydrodynamic-sediment transport model to investigate sediment processes in the Belgian Coastal Zone focusing on two complementary aspects of the sediment dynamics: the internal sediment motion and redistribution within the Belgian coast; and the horizontal transport.
Numerical Modelling of Suspended Sediment Transport in the Loire Estuary
In order to evaluate silt displacements and deposits in the outer part of the Loire Estuary over one year, a two-dimensional depth-integrated model of suspended sediment transport has been carried out. It takes into account transport and dispersion of suspended sediment by tidal currents, and processes of erosion, deposition and bed consolidation. Erosion laws and consolidation laws are specific of the Loire Estuary and come from laboratory experiments. Representative tidal conditions and river Loire flowrates have been identified : results of the model for these typical cases will be tentatively extrapolated to a one year evolution.