Details

A dedicated setup of the Westerschelde model was developed to study the water-quality and ecological impacts of an increase of the water flow (and salinity) coming into the estuary via the Bath inlet. Several hypotheses and adaptations of time-dependent inputs were made to come up with a consistent set of water-quality scenarios aiming at calculating the impacts of suddenly changing the operations of the sluices at Bath and the water-quality in the Volkerak-Zoommeer. The impacts on salinity, dissolved oxygen, total nitrogen and phosphorus, and chlorophyll a, were analysed for two scenarios and compared to the baseline along a longitudinal
transect in the Westerschelde estuary. Both scenarios showed an impact that was mostly located in the vicinity of the inlet and in the upstream part of the estuary. The extra water flow for the scenarios had limited influence on the water-quality, even though the time-period investigated covered the summer when all the river discharges are low and the Bath inlet is comparatively larger. The effect of the loadings was also quantified for two extreme conditions, but none of them showed any significant impact on the chlorophyll a concentrations. Due to the limitations of the period and the setup of the model scenarios these results cannot be taken at face value. They should be seen as initial assessments of potential effects.