Leeway Dam
At the eastern edge of Amsterdam, the housing area IJburg is under construction on six islands located in the shallow water of the IJmeer (with a total of 18,000 houses). To qualitatively compensate for the loss of biotopes, nature development projects are to be constructed elsewhere in the IJmeer.
The proposed leeway dam in front of the coast of Waterland is located on the site where a dike was located during the Middle Ages. The dam is situated such that, with a curve, a bay is shaped between two protruding points in the the shore line. Behind the dam, a protected and shallow wetland environment is created. It gradually makes a transition to the planted shores, and the wetland and the meadows of the polder.
The dam consists of sand, and is at the outside protected from the waves by an edge of riprap. By its location above water level, the dam will be covered with shrubs. The level of the dam is chosen such that the dam will be partially flooded during a 5 or 10 year storm. Therefore, the natural dynamics of the system will influence the vegetal development. The rear side of the dam will gradually change into a shallow wetland environment, as little by little clay and peat will be deposited here.
Wind and wave protection, and the availability of nutrients will make the space behind the dam valuable as a rest- and fouraging area for aquatic birds, and as a wetland zone rich in natural processes.
