Integratie van ecologie en waterbouwkunde in de Zeeschelde: aanleiding tot en situering van het Onderzoek Milieu-Effecten Sigmaplan (OMES)
Research output: Contribution to journal › A3: Article in a journal without peer review
The ideas of integrated water management form the basis for the water policy in Flanders. This requires however a thorough understanding of how the watersystem is working. This allows then to workout these management options which fulfil the aims of several functions. The Schelde estuary is a very important river in Flanders. It is the entrance to the port of Antwerp but also a very important ecosystem. Especially the brackish and freshwater tidal mudflats and marshes are, on a European scale, very rare habitats. However, due to increasing high water levels, the execution of the Sigmaplan is very urgent in order to protect the land from being flooded. The Sigmaplan consists of heighthening and stengthening the dikes and the creation of inundation areas. For the further execution of the Sigmaplan several alternatives are available: dikes can be build so as to enhance vegetation growth, dikes can be moved more inland to create new intertidal areas and finally the controlled inundation areas can be managed in such a way that they area flooded very regularly. As the execution of this plan clearly influences the estuarine ecosystem the Flemish government decided to carry out a largescale research project to build an ecosystem model of the estuary. Based on the results of this research and the ecosystem model the impact of alternatives of the Sigmaplan on the system should be estimated. This will be a very effective tool for the integrated management of the estuary. To achieve this goal the OMES project aims at building an ecosystem model of the Schelde estuary, especially of the ZeeSchelde, to predict the impact of different alternative construction and management options for the Sigmaplan. This model will focus on the processes occurring in the pelagic and benthic phase and especially on the benthic pelagic coupling. What is the role of the intertidal areas in the flux of C and N? Therefore the research task consists of measuring water quality parameters, phyto- and zooplankton composition and production along the estuarine gradient, the composition of the organic matter in the water column, the source and the fate of this organic matter. Within the benthic compartment detailed studies on the benthic fauna and on denitrification rates of the sediment are included. From the marshes the parameters influencing the occurrence of different vegetation types are studied as well as the production of several dominating vegetation species (Reed, Phragmites australis; Willows, Salix sp.). Sediment transport within the river as well as sedimentation and erosion on marshes and mudflats are studied, coupled with the hydraulics of the estuary. Finally the results of these studies and the ecosystem model will be used to answer the questions what will be the impact on the ecosystem of increasing or decreasing the surface of intertidal areas (by e.g. building new dikes further from the river) or of different management options of the controlled inundation areas. Do the freshwater tidal marshes play a significant role in nitrate removal and nutrient turnover? What is the impact of a larger tidal area on waterheights? Are marshes sources or sinks of organic matter? These are just a few of the questions adressed by the project. The project is financed and coordinated by the Ministry of the Flemish Community. The overall coordination is done by the Institute of Nature Conservation in cooperation with the Administration of Waterways and Waterinfrastructure which is responsible for the execution of the Sigmplan. The project lasts for three years and started mid-1995. Several research tasks are carried out by the Institute of Nature Conservation and the Hydraulic laboratory of the Flemish Ministry, others are contracted out to several laboratories of the Flemish Universities (3 at the University of Gent; 2 at the University of Brussel; 1 at the University of Leuven), the Koninklijk Belgisch Instituut voor Natuurwetenschappen (Brussel) and the Netherlands Institute of Ecological Research, Centre for estuarine and marine ecology (Yerseke, Nl).
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