Erika Van den Bergh

THE SCHELDT ESTUARY: A DESCRIPTION OF A CHANGING ECOSYSTEM

Estuaries are naturally highly dynamic and rapidly changing systems, forming a complex mixture of many different habitat types. They are very productive biomes and support many important ecosystem functions: biogeochemical cycling and movement of nutrients, mitigation of floods, maintenance of biodiversity and biological production. Human pressure on estuaries is very high. On the other hand, it is recognized that estuaries have a unique functional and structural biodiversity. Therefore, these ecosystems are particularly important for integrating sound ecological management with sustainable economics. These opportunities are explored for the Scheldt estuary, a well-documented system with an exceptional tidal freshwater area. In this article a description of the Scheldt estuary is presented, illustrating that human influence is intertwined with natural dynamics. Hydrology, geomorphology, trophic status and diversity are discussed, and possible future trends in both natural evolution and management are argued.

Nature development along the river Scheldt: Combining ecosystem functions in the Kruibeke-Bazel-Rupelmonde polder

In the wake of current water management problems, new legislation and a rising public awareness concerning environmental problems, new opportunities for nature development arise. The ecosystem management concept of restoring native ecosystems and rehabilitating original ecosystem functions and processes (such as nutrient cycles and hydrological processes) is being applied along the river Scheldt. Based on analysis and estimates of current and future problems in both the valley and the estuary, a conceptual rehabilitation model with a long-term vision is developed to tackle these problems. This vision is then translated into concrete plans and implementations trying to combine safety measures against flooding as much as possible with ecological rehabilitation and the creation of sustainable river related nature. The entire process from vision building, problem analysis and model making to concrete nature development plans is outlined in this article for the example of an ambitious nature development project in the Kruibeke-Bazel-Rupelmonde polder. The entire landscape (over 500 ha) will be rehabilitated, not by restoring the ecological patterns, but mainly by creating opportunities for ecological processes to take place, such as tides, inundation, seepage and grazing.