Article révisé par les pairs
Résumé : Since about 10 years, studies have been conducted at the University of Brussels in modelling the microbiological processes affecting biogenic substances in the Schelde estuary and its watershed. The first model, a one dimensional redox model, simulated the longitudinal distribution of oxygen, nitrate, iron and manganese in relation to the observed bacterial heterotrophic activity. A model allowing calculation of bacterial activity from data on organic discharge was coupled to this model. It was completed by a model of phytoplanktonic development within the estuary. Finally, an idealized model of the hydrographical network, based on Horton analysis, is being established in order to calculate the quality of the water at the downward boundary of the estuary. Together, all these sub-models form a general model of the ecological working of the Schelde estuary, able to predict at least the general trends of the redox state, the organic carbon, mineral nitrogen, and chlorophyll-a concentrations as a function of distance to the sea, from the knowledge of geomorphological and meteorological data, along with informations concerning the distribution of anthropogenic discharges. This model therefore provides a powerfull tool for the rational management of the Schelde estuary.