Introducing the VIMM toolbox for the (re)calibration of the SCALDIS model

Hydrodynamic

Development of a mud transport model for the Scheldt estuary in the framework of LTV

In 2006, a work plan was conceived for the development of a mud transport model for the Scheldt estuary in the framework of LTV (Long Term Vision) (Winterwerp and De Kok, 2006). The purpose of this model is to support managers of the Scheldt estuary with the solution of a number of managerial issues. Also in 2006, the first two phases were initiated. The present report discusses the activities that have been carried out during the first half of 2007, i.e. Further improvement of the hydrodynamic and mud transport model.At a technical level, all model improvements scheduled for 2007 have been implemented. The most important developments are: longer hydrodynamic simulation period (up to one year), more accurate concentration boundary conditions, variable wave effects and biological effects.The hydrodynamic simulation yields realistic values for water levels and salinities, although it is expected that the modelled velocities will be too high. Three actions are identified that can enhance the simulated hydrodynamics:The high fresh water inflow event in the beginning of March can be modelled more accurately by adding more data points in the time series of fresh water inflow to increase the volume of fresh water contained in the peak.The time series of fresh water inflow of the Bathse Spuikanaal has to be added in the modelA different set of boundary conditions could yield better results for water levels.Regarding the mud transport simulations, the following is concluded:A minor shift of two dumping locations near Antwerp much improves the proper modelling of the ETMNew concentration boundary conditions at sea result in more realistic SPM concentrations at seaThe difference between simulations with 5 and 10 horizontal layers is only minorVariable waves temporarily enhance the concentration in the western part of the Western Scheldt during stormsThe biological impact on large-scale SPM concentrations in the Scheldt estuary appears to be minorThe SPM levels appear to be rather sensitive to the volume of harbour situation and dumpin

The unstructured Scaldis model: a new 3D high resolution model for hydrodynamics and sediment transport in the tidal Scheldt

In the framework of the projects "Integral Plan for the Upper Sea Scheldt" and "Agenda for the Future", the SCALDIS model, a new unstructured high resolution model of the tidal Scheldt is developed in TELEMAC 3D (Telemac-Mascaret software platform). Starting from the stated model purpose, a weighted dimensionless cost function is set up that attributes equal weight to the vertical and the horizontal tide. By adapting the bottom roughness, the cost function is minimized during model calibration. Quantification of the model skill and cost function calculation is done using the VIMM toolbox which is developed and maintained at Flanders Hydraulics Research. The quantified model skill of the SCALDIS model shows that the model is well suited to assess the effects of changing the bathymetry and geometry of the Scheldt river on water levels, velocities, tracer dispersion and residence times, and that the hydrodynamics can be used as the basis for sediment transport calculations (both cohesive and non-cohesive)