Development of a Water Quality and Bio-Accumulation Model for the Scheldt Estuary

Abstract

Estuaries are one of the most important coastal features for mankind. Large civilizations have developed on the shores of many estuaries and most of the present day harbours and large industries are located within their sphere. This often results in water quality problems in many estuaries, including the Scheldt estuary. This estuary is faced with two major problems:

• 1. Extensive dredging and dumping operations of (contaminated) sediments, necessary to keep the port of Antwerp accessible and

• 2. Large domestic and industrial waste-water discharges. This results, for example, in low or even zero oxygen concentrations in the upper estuary and high concentrations of micro-pollutants in the biota and abiota.

A few years ago Rijkswaterstaat, the authority responsible for the management of the Western Scheldt, decided to built a management oriented model related to the second problem: the influence of the large waste—water discharges on the ecosystem of the Western Scheldt. The objective of the project was to develop a coupled transport, chemical/biochemical and bio-accumulation model for pollutants/micro-pollutants for the Scheldt estuary Pollutants/micro-pollutants in this context does not only mean heavy metals and/or organics, but also BOD, COD and nutrients (N, P. Si). The model attempts to relate the pollutant discharges into the estuary to the concentrations found in organisms (Tidal Waters Division, 1987).