A protection strategy for the floodplains of the River Yzer (Flanders, Belgium)

The Yzer is a lowland river, which rises in Northern France and discharges into the North Sea in Western Flanders (Belgium). Its capture area amounts to 1101 km². In the downstream part (polder area), the river has been canalised and embanked for navigation since the Middle Ages. Along the western part of the middle section of the river the original, wide floodplain was preserved and still floods several times every winter. This floodplain area has a high ecological value and was designated as Ramsar and Special Protection Area under the EU Bird Directive. Due to large peak run-offs during the last decade, several times also houses and farms were endangered. An integrated project for flood protection of houses and nature restoration was elaborated. Aiming at a policy of integrated water management, the Flemish Waterways and Maritime Affairs Administration (AWZ) are developing a new strategic planning instrument on the multiple functions of waterways with much more attention for nature conservation and nature restoration than in the past. The Institute of Nature Conservation was contracted since 1998 to elaborate an ecosystem vision and nature rehabilitation scenarios for the different Flemish waterways. These studies start with an analysis of abiotic and biotic conditions, historical reference data and current land use of the water system. This information enables the detection of the different bottlenecks that cause ecological deterioration. Within social, economic and ecological preconditions, realistic targets for nature restoration and development are formulated. Basic principle is to develop a sustainable ecosystem, neutralizing the bottlenecks as much as possible, providing (more) space for dynamic fluvial processes, and restoring the relation between river and floodplain. The aim is to (re)create and restore diverse wetland, floodplain and river habitats, and to develop an optimal corridor function of the river. The objectives are concretized in 2 or 3 alternative nature development scenarios, each with a different level of ambition. In each scenario zones are indicated where nature is of primary, additional or basic importance, as well as the most important measures to be taken. This allows for the elaboration of specific action plans in the different parts of the river basin.