BW-04
Polder overflow & saltmarsh
Kesterhaven,
Netherlands
53.1871° N, 4.8113° E
( Site file
A managed realignment behind 4.62 km of dike front: 62 ha of new saltmarsh that cuts wave height at the dike toe by 38 %.
The problem
The Kesterhaven dike held the estuary in front of 728 homes on its own. Every winter, waves broke directly on the toe of the dike, and the water board was repairing the same stretch again and again.
What we built
With the Kesterhaven Water Board, under agreement KH-2023-008, we opened a controlled overflow into a low polder and let the tide back in. Commissioned in June 2023, the realignment has grown 62 ha of saltmarsh along 4.62 km of dike front. The marsh takes the energy out of the waves before they reach the dike.
Wave sensors at the dike toe compare each storm with the baseline. Wave height went from 1.46 m to 0.91 m, 38 % lower. The entry is reported and goes to Atlantic Survey Review for its annual check.
Pieter Hoekstra, Dike Warden at the Kesterhaven Water Board, puts it this way: “The marsh does the work the dike used to do alone. We can see it in the wave readings.”
Coordinates
53.1871° N, 4.8113° E
Commissioned
Structure
Managed realignment, 62 ha saltmarsh
Scale
4.62 km of dike front
Partner
Kesterhaven Water Board
Homes behind the line
728
Sensors
31
Status
Operational
−38 %
wave height at the dike toe
( Readings
What this site measures,
and who checks it.
R-0438
Wave height at the dike toe
−38 %
Atlantic Survey Review
Reported
R-0439
Saltmarsh area above mean high water
+62 ha
Atlantic Survey Review
Verified
