Winter dike and summer dike

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Summer dike and winter dike on the North Sea in Dorum near Cuxhaven
Summer dike at the mouth of the Hunt at Elsfleth . Since the Weser arm Westergate was dyed (foreground) and the Huntes barrier was built , it is now behind the winter dike instead of in front

On many coastlines and rivers there are two lines of dikes , the winter dike or main dike and the summer dike .

Winter dike

The so-called winter dike is so high and stable that it can withstand even the highest expected floods - on the coast , storm surges .

Summer dike

A summer dike is a flat dike with a height of about 1.2 to 2 meters, which prevents minor floods, especially tidal floods on coasts and estuaries , and thus enables the cultivation of the land before the winter dike. On the German coasts, the areas protected by the summer dike are called summer kog, polder or grass.

The summer dike should be designed so that the winter flood can pass over it without causing damage. Therefore, the embankment on the inland side must be flatter than on the lake side.

Summer dikes increase the safety of the winter dikes behind them:

  • They also act as breakwaters on the seashore .
  • In rivers, their flooding causes the cross-section of the water to become wider when there is a high flow and the water level therefore rises less than when the winter dykes are on the river bank.

Some islands, such as Hallig Hooge, have summer dikes, but no winter dikes. There the buildings are erected on terps to protect against flooding .

Summer dykes are also useful in land reclamation . Due to the regular flooding, sediments are deposited in the summer grasses behind , which slowly increases their soil level.

Web links

  • Hanz Dieter Niemeyer u. Ralf Kaiser: Hydrodynamic effectiveness of Lahnungen, Hellern and summer dykes . In: The coast . No. 64 , 2001, p. 15–60 ( online [PDF; accessed March 12, 2014]).
  • Lexicon of the dike association Xanten-Keve. Retrieved March 12, 2014 .