Van Oord has completed its work on the artificial tidal system known as the Fish Migration River at the Afsluitdijk in the Netherlands.
The final part of Van Oord's contribution comprised the completion of the dam separating the Fish Migration River from the IJsselmeer. The construction of this river was commissioned by the Province of Friesland.
The dam, the final component constructed by Van Oord, surrounds the Fish Migration River and protects it from wind, waves and currents. In addition, the dam helps in managing brackish water in the river.
Van Oord previously implemented the estuary on the Wadden Sea side and the Lake IJsselmeer side. In addition, as part of the Afsluitdijk dyke reinforcement project carried out by the construction consortium Levvel (consisting of BAM, Van Oord, Rebel and Invesis) and commissioned by Rijkswaterstaat, Van Oord was involved in the implementation of the gap through the Afsluitdijk.
The gap in the Afsluitdijk allows migrating fish from the sea to access the new tidal system.
For the construction of the dam, Van Oord used raw materials from the immediate area as much as possible. The sand was extracted from Lake IJsselmeer using the cutter suction dredger Biesbosch.
A total of 400,000 cubic metres of sand was extracted from the seabed right next to the Fish Migration River, eliminating the need to buy and bring in raw materials. Some 20,000 tonnes of quarry stone used for reinforcing the Afsluitdijk was also reused.
Van Oord said the use of area-specific material also contributes to the success of fish migration. Specifically, the sand and rock have the same smell and taste as the environment, thus helping fish with their orientation.
The next step in the construction of the Fish Migration River will be the construction of the meandering river. The Province of Friesland is expected to start implementation of this step in 2026.
The tidal system will help migratory fish grow and reproduce, as it will give them access to both saltwater and fresh water.