The Wadden Islands are a chain of barrier islands in front of the Dutch coast. The inhabited parts of the islands are protected by dikes. The uninhabited parts of the islands are not artificially protected and therefore subject to natural processes. The shores of the islands show erosion and accretion in different places. There are also many different trends over time in erosion and sedimentation.
The cause of the structural erosion is mainly due to sea level rise: the tidal flats grow with sea level and import into the Wadden Sea increases. Acute erosion can also occur in a case of a severe storm.
Erosion along the North Sea coast causes a high risk of flooding. Firstly, erosion is a threat for natural areas: dunes and salt marshes. These are generally being seen as more important: if dunes disappear, urban areas are being threatened, as are houses built for recreational and tourism purposes. For the local people, tourism and recreation is the main source of income. The policy option is called dynamic preservation in the Netherlands, because, where possible (from a safety point of view), maximum freedom is offered for natural processes.