A coupled, fully transient, multi-component reaction-transport model has been developed to estimate the long-term fluxes of reactive compounds in strong tidal estuaries and applied to the Scheldt estuary (Belgium and The Netherlands).
Rate formulations were determined independently from laboratory experiments.
The model provides a realistic description of estuarine tidal and residual circulation and includes the essential feedback mechanisms between interdependent chemical species.

The problem of coastal eutrophication and the control of algal blooms by the riverine fluxes of nitrogen to the North Sea has been considered. Using the typical case of the Scheldt estuary, it has been demonstrated that the short duration of the algal blooms requires estuarine flux estimation methods with a high temporal resolution. The need to resolve the processes and fluxes temporally calls into question the traditional sampling strategy based on instantaneous longitudinal profiles. Our model results indicate that the temporal variability of the synoptic scale should be resolved in detail. In this respect, long- time series of field data are imperatively needed.

The model has also been applied in the frame of the BIOGEST programme (Biogas in Estuaries), to estimate the estuarine contribution to the emission of selected biogenic gases (CO₂, NH₃ and N₂O).

Contact for further information: vdborght@ulb.ac.be