Denmark

Coastal erosion Denmark

Vulnerabilities

Denmark consists of the Jutland peninsula and more than 400 islands. The whole of the country is lowland. The surface was formed by Ice Age glaciers and glacial streams. The highest hill is approximately 170 metres above sea level. The coastline has a length of more than 7300 km. To protect low-lying land against flooding and storm surge, dikes or other permanent installations have been built along about 1800 km of coastline (3). Five types of coastline can be identified: rocky coast, soft cliff coast, tidal flat / marsh coast, protected coast, and sandy dune coast. Some parts of the coast are eroding, such as northern Jutland (2-4 m/year)) and the central west (North Sea) coast (2-8 m/year) (1).

The Danish coastline partly comprises active coastal cliffs where the sea erodes material, and partly beach-ridge complexes, where the material is deposited in the lee of prevailing winds. About 80% of the population lives in urban areas connected to the coast. In recent years beach nourishment has increasingly been used to protect exposed stretches of coastline (3).

For Denmark a mean sea level rise has been projected of 0.15-0.45 m for 2050 and 0.30-1 m for 2100, excluding vertical land movement. Maximum wind speed during storms is projected to increase between 1 and 10% until 2100 (2). Increased sea level rise and increased storminess will increase erosion rates. The increase will be largest along the western and northern coastline, and may be an additional 5.0-7.0 m/year in these parts (1).

It appears that impacts due to possible changes in the direction and strength of winds may be as important as those attributed to sea level rise. By and large, expected impacts could probably be counteracted by running maintenance. Beach nourishment is an increasingly used technique. In 1992 it was estimated (4) that it would cost about 60 million Dkr. per cm sea level rise on 120 km of the west coast of Jutland from Lodbjerg to Nymindegab.

Adaptation strategies

The opportunities for continuous climate change adaptation are generally good, and in some areas are already underway. Where coastal erosion is countered by regular beach nourishment with sand, individual site owners just increase the amount of sand to correspond to actual needs (4). The Danish adaptation strategy allows site owners to raise the beach at their own cost by regular beach nourishment to combat coastal erosion. Generally speaking, it is a land owner’s own choice whether and how to protect themselves from flooding and erosion (5). The same applies to channel dredging, where the amount dredged can be increased as required (4). The estimated additional erosion can be counteracted easily by coastal protection measures such as increased sand nourishment volumes or a heightening of groins and breakwaters (1,6).

Compared with 2008 the additional artificial supply for compensating for anticipated climate change effects is estimated to be 17% in 2050 and 49% in 2100 (7).  

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Denmark.

1. Sørensen (2013)
2. Klimatilpasning (2010), in: Sørensen (2013)
3. Danish Ministry of the Environment (2005)
4. Jacobsen et al. (1992), in: Fenger (2000)
5. Dronkers and Stojanovic (2016)
6. Niemeyer et al. (2016)
7. Jensen and Sørensen (2008), in: Niemeyer et al. (2016)