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Multi-scale modelling of the Scheldt Estuary

The Scheldt basin, located in Northern France, Belgium and the Netherlands, represents an extreme case of water pollution due to the high population density (over 500 inhabitants per square kilometer), active industrial development and its intensive agriculture and animal farming.

The Scheldt estuary

As the Scheldt Estuary is generally well-mixed with little or no vertical structure and small salinity gradients due to a small residual flow, a depth averaged 2D model is therefore sufficient for capturing the dominant dynamics. The width of the estuary ranges from 8km near the mouth (at Vlissingen) to 1.5km near the Dutch/Belgian border narrowing down to 50 meters in Ghent. As it is fairly impractical to use a 2D model on such narrow channels, the rivers upstream of Hemiksem are described with a 1D model.

Unstructured mesh of the entire domain

SLIM can simulate the barotropic flow in the North Sea and then the propagation of the tidal signal in the estuary and the in the branching river network. By using a wetting and drying algorithm, we can explicitly represent emerging sandbanks at low tide (shown in black). The model has been further used to simulate the transport of fecal bacteria, sediments and radioactive tracers in this multi-scale domain.

 

External collaborators

Prof. Eric Delhez (University of Li├Ęge)

To learn more…

Naithani, J., de Brye, B., Buyze, E., Vyverman, W., Legat, V., & Deleersnijder, E. (2016). An ecological model for the Scheldt estuary and tidal rivers ecosystem: spatial and temporal variability of plankton. Hydrobiologia, 775(1), 51–67. https://doi.org/10.1007/s10750-016-2710-1
Elskens, M., Gourgue, O., Baeyens, W., Chou, L., Deleersnijder, E., Leermakers, M., & de Brauwere, A. (2014). Modelling metal speciation in the Scheldt Estuary: Combining a flexible-resolution transport model with empirical functions. Science of The Total Environment, 476477, 346–358. https://doi.org/10.1016/j.scitotenv.2013.12.047
Delhez, É. J. M., de Brye, B., de Brauwere, A., & Deleersnijder, É. (2014). Residence time vs influence time. Journal of Marine Systems, 132, 185–195. https://doi.org/10.1016/j.jmarsys.2013.12.005
de Brauwere, A., Gourgue, O., de Brye, B., Servais, P., Ouattara, N. K., & Deleersnijder, E. (2014). Integrated modelling of faecal contamination in a densely populated river–sea continuum (Scheldt River and Estuary). Science of The Total Environment, 468469, 31–45. https://doi.org/10.1016/j.scitotenv.2013.08.019
Gourgue, O., Baeyens, W., Chen, M. S., de Brauwere, A., de Brye, B., Deleersnijder, E., … Legat, V. (2013). A depth-averaged two-dimensional sediment transport model for environmental studies in the Scheldt Estuary and tidal river network. Journal of Marine Systems, 128, 27–39. https://doi.org/10.1016/j.jmarsys.2013.03.014
de Brye, B., de Brauwere, A., Gourgue, O., Delhez, E. J. M., & Deleersnijder, E. (2012). Water renewal timescales in the Scheldt Estuary. Journal of Marine Systems, 94, 74–86. https://doi.org/10.1016/j.jmarsys.2011.10.013
Kärnä, T., de Brye, B., Gourgue, O., Lambrechts, J., Comblen, R., Legat, V., & Deleersnijder, E. (2011). A fully implicit wetting–drying method for DG-FEM shallow water models, with an application to the Scheldt Estuary. Computer Methods in Applied Mechanics and Engineering, 200(5–8), 509–524. https://doi.org/10.1016/j.cma.2010.07.001
de Brauwere, A., de Brye, B., Servais, P., Passerat, J., & Deleersnijder, E. (2011). Modelling Escherichia coli concentrations in the tidal Scheldt river and estuary. Water Research, 45(9), 2724–2738. https://doi.org/10.1016/j.watres.2011.02.003
de Brauwere, A., de Brye, B., Blaise, S., & Deleersnijder, E. (2011). Residence time, exposure time and connectivity in the Scheldt Estuary. Journal of Marine Systems, 84(3–4), 85–95. https://doi.org/10.1016/j.jmarsys.2010.10.001
de Brye, B., de Brauwere, A., Gourgue, O., Kärnä, T., Lambrechts, J., Comblen, R., & Deleersnijder, E. (2010). A finite-element, multi-scale model of the Scheldt tributaries, river, estuary and ROFI. Coastal Engineering, 57(9), 850–863. https://doi.org/10.1016/j.coastaleng.2010.04.001
Blaise, S., de Brye, B., de Brauwere, A., Deleersnijder, E., Delhez, E. J. M., & Comblen, R. (2010). Capturing the residence time boundary layer—application to the Scheldt Estuary. Ocean Dynamics, 60(3), 535–554. https://doi.org/10.1007/s10236-010-0272-8
Gourgue, O., Comblen, R., Lambrechts, J., Kärnä, T., Legat, V., & Deleersnijder, E. (2009). A flux-limiting wetting–drying method for finite-element shallow-water models, with application to the Scheldt Estuary. Advances in Water Resources, 32(12), 1726–1739. https://doi.org/10.1016/j.advwatres.2009.09.005
de Brauwere, A., De Ridder, F., Gourgue, O., Lambrechts, J., Comblen, R., Pintelon, R., … Deleersnijder, E. (2009). Design of a sampling strategy to optimally calibrate a reactive transport model: Exploring the potential for Escherichia coli in the Scheldt Estuary. Environmental Modelling & Software, 24(8), 969–981. https://doi.org/10.1016/j.envsoft.2009.02.004