Transportmodellen voor waterkwaliteitsparameters in een tijrivier
Boury, P.; De Laet, W. (1984). Transportmodellen voor waterkwaliteitsparameters in een tijrivier. Ir Thesis. Katholieke Universiteit Leuven. Departement Bouwkunde: Leuven. 2 vol. pp.
The purpose of this work is to develop a model that can be used to predict the water quality of a tidal river, in this case of the Western-Scheldt estuary. The method is general and in that way it can be employed on all well mixed estuaries. In order to characterize the quality of the water we use four parameters: the salt concentration, the exces of the temperature, the biochemical oxygen demand and the amount of dissolved oxygen. One must say that this is not a chemical study but a hydraulic study wich discribes the transport of the above-mentioned parameters.
We calculate dependent on the tide. For the calculation of the flows and the water depths we use a model developed at the "labo hydraulica" of the K.U. Louvain. This model is based on a finite difference approach, made out according to the implicit Preissmann-scheme and solved by means of the double sweep methode implicit schemes have, on the whole, a better stability, so that one can work with a larger time-step. That's why we have first put up finite difference models to solve the transport equations. However, none of the two models we have tested have lead to proper results.
We then have worked out an explicit finite difference model, this has indeed given proper results. By means of these results we can compare tide-dependent models with tide-averaged models and we can find out wether the excess of calculation time is worth the trouble. What is the comparative importance of dispersive and advective transport. To what extent is, as a result of the tide-run, a tributary influenced by what is happening in the Scheldt itself.
We restrict ourselves to a one-dimensional study. In order to predict the far field effects this approach can lead to good results. In order to get more significant results of the near field, one should work with more detailed models.
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