Project part-financed by the European Union (European Regional Development Fund)

The Interreg IVB North Sea Region Programme

The authors are solely responsible for the content of this report. Material included herein does not represent the opinion of the European Community, and the European Community is not responsible for any use that might be made of it.
Back to overview measures

Heusden LO wetland - small scale tidal wetland restoration in the freshwater zone of the Sea Scheldt

Measure description

The Heusden LO wetland is an area of 10 hectare in the freshwater zone at the left bank of the Sea Scheldt (near Heusden (Gent), downstream Heusdenbrug).

At the location of Heusden LO, they decided to relocate the dike. By doing so, a small tidal wetland could develop in an area of the Sea Scheldt where tidal wetlands with mudflats and marshes are scarce. This opportunity came along when the existing dike needed to be elevated to "Sigma-height", and several alternative locations were considered. The old dike was lowered to mean high water level and two breaches to mean low water level were excavated where the old drainage sluices used to be. Because there is no shipping in this area and because dynamics are low, the new dike was not reinforced with stone rubble.

The restoration location existed mainly of grassland and cropland with also a moist willow bush surrounded by poplar plants where the Scheldt bends. In the North-western part used to be a meadow with a triangular pond. The pond is characterized by few aquatic plants and the meadow around is lower in elevation.
During the restoration works, the dike was breached through which the meadow area in the North-western part had already developed into an intertidal flat habitat before the restoration was done. During the summer, the breach was filled up again and the mud area was colonized by pioneer vegetation.
The most southern part of the area was elevated above mean water level because of the presence of a sand stock during the restoration works. Therefore, this part of the area was rarely flooded.
The most northern part of the area (northern from the pond) was flooded from the south at neap tide because the dike was not breached at this location. The drainage was also slow and inefficient because of the limited flow out possibilities.
At the end of the restoration works, the area was completely vegetated by the original vegetation. Only the area around the pond was colonized by pioneer vegetation during summer. In the beginning of the monitoring program, the area was a marsh with limited drainage during low water.

Besides the possibility to improve the connectivity in this area, developing this kind of habitat is expected to contribute in de reduction of tidal energy, increase of flood protection, improvement of oxygen condition, improvement of nutrient conditions, and improvement of self-purifying power.

The construction of the Heusden LO wetland fits in the frame of the Sigmaplan (management plan for flood defence in the Scheldt estuary), the dike needed to be broadened and elevated. Analysis of the evolution after restoration fits in with the decisions about the Development outline 2010 and Long Term Vision 2030 (Dutch and Flemish agreement on integrating accessibility, naturalness and flood safety) and the updated Sigmaplan (Flemish plan for flood protection combined with ecological objectives), of the Dutch and Flemish governments, that committed them to leap forward with the ecological rehabilitation of the Scheldt estuary. An important challenge is the creation of tidal wetlands by transformation of woods or agricultural land into tidal mudflats and marshes. In order to assess the feasibility and to identify possible problems any small scale projects already in place, such as Heusden-LO, are studied in detail to improve our apprehension of the similar larger scale future plans.

Back to top

Important to know

Reports / Measures / Tools

Report: Management measures analysis and comparison