The harbour, safety damming and drainage
After the breaking through and formation of the present Thyborøn Channel in 1862, the coastline retreated 15- 20 metres a year. For protection against the sea and to keep the channel navigable, about 100 breakwaters were built along the coast.
Thyborøn Harbour was built in 1914-17, the population increased, and in 1940 there were about 1,200 inhabitants and about 100 fishing boats. A commission appointed in 1937 recommended closing the channel by damming and the installation of sluice gates, and construction then commenced.
But economies meant that building stopped in 1954, and only the constructions shown in the figure were completed.
Thyborøn Channel
Until 1862 the west coast near Thyborøn was an isthmus except when the sea broke through a few times, breaches which were quickly closed again by the sea current. In 1862 a storm broke through the isthmus in two places – at Agger and at Thyborøn. The breach at Agger was soon filled with sand while the breach at Thyborøn was to become the Thyborøn Channel, which is about 1 kilometre wide and gives access to the Limfjord (Lime Fjord).
In 1946 the Danish parliament decided to build at a sluice and floodgate at Thyborøn in order to control water levels in the Limfjord, thus protecting low-lying farmlands. The floodgate would also protect the isthmus , the canal for ships and the harbour against storm tides and general flooding.
Between 1875 and 1933 groynes were built along the coast in order to stop the sea from eating land at the rate of 15 to 20 metres a year. The result of this is that only about two metres a year are lost to the sea at Bovbjerg. Besides, Thyborøn was protected with dikes to the west and the south. Also Harboøre was protected with dikes.
The groynes on both sides of the channel were enlarged and extended into breakwaters where the sluice and locks were to be built. Construction was stopped in 1954 because of funding problems and because some people began questioning the necessity of closing the channel. In 1970 the plan was abandoned.
Today the Danish Coastal Authority is responsible for the maintenance of dikes and groynes. They also employ a new protective measure where huge amounts of sand are pumped onto the beach in order to feed the greedy sea and postpone the retreat of the coast.
The area south of Thyborøn and west of the protective dike consists of about 500 hectares of brackish lakes or lagunes, about 500 hectares of salt meadows, and about 100 hectares of dunes, reed thickets, scrub and dikes. Before the protective dike was built the area was part of the Limfjord called Nissum Bredning, but when the dike with the railway and the road was built, the area was closed in.
The two lakes are connected with a narrow ditch and there is a sluice at the northern end. It was removed in 1998 in order to allow the brackish water in the lakes to be exchanged with salt water. Now the sluice is working again in the breeding season of the meadow birds, preventing the flooding of nests and young birds and creating better feeding possibilities during migration. Outside that season the sluice is supposed to be fully open.