The sea constantly removes clay and sand from the beach. The coastline recedes with a speed of 1-2 m per year.
The erosion is an interaction between wind and precipitation. When it rains, the rain water seeps down through the sand; until it reaches the compact clay stratum. The water flows over the surface of the clay toward the coast, where it trickles out in the middle of the cliff.
It can be expected that climate changes in the future will result in an increased number of strong storms and thereby accelerate the erosion of the coast.
- The sea slowly devours the cliff and the water along the beach has been coloured brown with clay and sand.
- Pressure hose.
If one wants to stop the erosion of the coast, a number of methods have been put forward:
- A draining of the cliff would delay the above described mechanism and would presumably be effective coast protection.
- Groynes and breakwaters would presumably also be effective, such as it is in Lønstrup. Especially if it is supplemented yearly with sand-feeding (lay sand out on the beach behind groynes). In Lønstrup there is laid out 20,000 - 30,000 m3/yearly.
- The digging of pipes into the beach (pressure equalizer pipes). This method has,for a trial period, been tested on a section of the beach. The method’s effectiveness has been intensely discussed. In the Spring of 2008 a report isexpected on the method’s possibilities. In the short run a coast protection would have both advantages and disadvantages.
Advantages of coast protection:
- The erosion of the coast would stop for a time, and the area behind the cliff would be preserved.
- Perhaps some of the buildings threatened today with falling into the sea could be protected.
- The shore would be broader like other beaches.
Disadvantages of coast protection:
- Landslides in the cliff would continue, but the material would remain on the beach. The active cliff will reach its passive equilibrium’s form. The cliff will become flat grown over with lyme grass and other cliff plants. The dramatic formations offered by an active and dynamic cliff would be lost.
- A coast protection would be visually disfiguring.