Beltringharder Koog
Saltwater biotope behind the sea dike in the Beltringharder Koog
In 1987, Nordstrand Bay was embanked, and the Beltringharder Koog was created in former tidal habitats. This was the last larger embankment along the Schleswig-Holstein coast. The measure aimed to improve flood safety and enhance inland drainage for inhabited coastal lowlands while the newly created polder was intended for agricultural purposes. In the planning phase, however, the project sparked highly controversial and emotional discussions, especially among NGOs and the affected local communities. One direct result of the newly erected dike was the loss of extensive coastal habitats.
To compensate for the loss of natural structures and functions, the entire polder was designated as nature reserve in 1991. Covering 3,350 hectares, it is the largest nature reserve on the Schleswig-Holstein mainland. About 845 hectares of the nature reserve were developed as an artificial coastal lagoon. Via two gates, tidal water flows in and out twice a day creating a strongly reduced local tidal range of around 0.4 meters (tidal prism 1.75 million m3). In winter, water is irregularly dammed over several tides to a height of one meter above mean sea level, simulating storm surges. About 380 hectares of the salt-water biotope are permanently submerged, while 170 hectares consist of intertidal flats, 215 hectares of salt marshes, and roughly 95 hectares of artificial islands. On these islands, important breeding colonies of rare terns, avocets, and plovers are present. Overall, a functioning artificial lagoon has emerged, a home to all the typical coastal communities, in a condensed area. Other parts of the nature reserve are designated as water storage basins, wetlands, and as a wilderness area (no uses, no management and no entry).
From an environmental view, it is a compromise: where tidal waters once flowed freely, there is now a managed area dominated largely by freshwater wetlands. Former eelgrass meadows are overgrown with reed. Deer, racoon dogs and other wild animals roam areas that once supported rich benthic fauna, providing food for fish and thousands of migratory birds. On the other hand, according to the nature conservation association Schutzstation Wattenmeer, which is responsible for the management, the nature reserve is one of the areas with the richest birdlife in Germany.
Why is it a NbS?
Integration of ecological aspects and concerns (habitat connectivity, species migration, set up of the new polder as a nature reserve with coastal lagoons, wetlands and wilderness areas) in the implementation of a necessary coastal flood defense and inland drainage measure.
Purpose of the NbS:
Improving flood safety and inland drainage for inhabited coastal lowlands.
Further information on this NbS:
Hofstede J.L.A. (2019). On the feasibility of managed retreat in the Wadden Sea of Schleswig-Holstein. Journal of Coastal Conservation 23:1069–1079. Link.
