A summer with record levels of rain has been a returning story in the news. This has prompted other stories such as what is happening to the coasts.
Are the Danish coasts slipping away?
‘In a geological context Denmark is a very young country and our coasts are constantly changing. Our coasts consist primarily of sand, gravel and clay. Wind, current and particularly the pounding impact of waves contribute to the constantly changing shape of the coast lines. At some of the most exposed places the coast may recede up to as much as 5 m annually’ says Ida Brøker, Head of DHI’s Coastal Department. ‘So, yes some places the coastline is ‘slipping’ away, however, other places it is exactly the opposite and we see accumulation, such as the Skaw Spit and the northernmost Wadensea Islands’.
Protecting the coast
‘In Denmark we have carried out coastal protection programs since the late 19 century. The first 100 years this was done solely by building hard structures as groynes and revetments. In the seventies the method of coast nourishment was employed. Sand is pumped up from the seabed far off the coast and then deposited on the sea bottom close to land or onto the beach itself’ says Ida Brøker and continues ‘annually 2-3 million m3 of sand are deposited this way along the West Coast of Jutland. By adding the amount of sand which corresponds to what the waves and current naturally remove a balance is achieved’.
Hard structures are also constructed at critical places along the Danish Coastline. It should however, be kept in mind that hard structures change the natural beauty of eroding coasts – an example is the cliff at Hundested – earlier a dramatic bare and steep cliff, which now is a flat and green slope protected by breakwaters.
The challenge ahead
‘We will in the future see an increased impact on our coasts. The changing climate will result in increased water levels, increased storm intensity with heavier rainfalls just as we have experienced recently. Protecting our lower lying cities will become a major challenge, presumable more than that posed by the changing coasts. Coastal erosion will continue and become even more severe so this is an area which we will have to focus more on. However, one should also bear in mind that climate changes occur over many years, hence it is possible to do something about it if we act prudently’ says Ida Brøker.