Bathtub effect (hydrology)

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Bathtub effect or sloshing effect are sometimes used terms in hydrology and meteorology for a sharp rise in sea ​​level in the coastal area of inland seas such as the Baltic Sea up to storm-like floods.

While a storm surge on the coasts of an open sea like the North Sea can be traced back to the connection between strong storms and the tidal range , it is caused on the coasts of the Baltic Sea by the fact that the water is pushed from the west towards Finland and the Baltic States by a persistent storm . In the western part of the Baltic Sea, this initially leads to low water . At the same time, additional water flows in from the North Sea at the Kattegat . When the wind subsides, the water “sloshes” from the eastern part of the Baltic Sea back to the west coasts of Germany and Denmark, causing flood levels there , as in December 2013, for example.

Under unfavorable circumstances, such floods can reach several meters above the normal level , as in the worst event of this kind for which historical records are preserved, the Baltic storm flood in 1872 . During this event, the water level rose more than three meters above normal height. Because there is no significant difference in tides in the Baltic Sea, such flood threats last much longer there than on the North Sea coasts.

Remarks

  1. ↑ G. Rosenhagen: Extreme storm surges on the German coasts. In: Deutscher Wetterdienst, Klimastatusbericht 2007, p. 81f; accessed November 26, 2018.
  2. ↑ G. Rosenhagen: Extreme storm surges on the German coasts. German Weather Service, Climate Status Report 2007, p. 81f; accessed November 26, 2018.
  3. ↑ B. Weidig: Flood of December 2nd, 2013. Federal Maritime and Hydrographic Agency, reports on storm surges and extreme water levels , Baltic Sea. The Baltic Sea flood of December 2nd, 2013; accessed November 26, 2018.
  4. ↑ Dieter Lohmann: It works without tides. Storm surges on the Baltic Sea. Dossier alarm on the dike. Is the risk of storm surge increasing? scinexx.de, April 20, 2002; accessed November 26, 2018.