Heverstrom

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The last canalised piece of the Heverstrom before it reaches Husum harbor
The Hever between Strand and Eiderstedt in the Middle Ages

The Heverstrom ( North Frisian : di Heewer ) is a tidal current that runs north of Eiderstedt through the North Frisian Wadden Sea . It washed away parts of what was then the island of Strand over a width of around 30 kilometers and in the course of history has repeatedly posed a threat to the islands of Pellworm and Nordstrand . Today the current connects Husum harbor through the Wadden Sea with the open North Sea .

The river begins as a lake gating between Eiderstedt and Süderoogsand before splitting into the Norderhever and the Heverstrom at Südfall . The Norderhever flows between Pellworm and Nordstrand and divides into several smaller arms at the Hallig Nordstrandischmoor . The Heverstrom flows along Eiderstedts until shortly before Husum.

The tidal basin of Heverstrom and Norderhever is the largest of the North Frisian Wadden Sea. It covers the entire area north of Eiderstedt. In the west it merges into the open North Sea, in the north the Süderoogsand, Pellworm and the Watthöhenscheiden border it between these points and the mainland. It covers 415.4 km² and has a volume of 1.753 billion m³ of water at medium high tide . The sublittoral area, which is constantly under water, covers 138.7 km², the eulitoral wadden area 276.6 km². The water volume is divided roughly halfway between the permanently existing tide volume with 905.3 million m³ and the incoming and outgoing tidal prism with 848.5 million m³.

Its permanently water-covered area increased by 80 km² from 1934 to 1990, the Heverstrom dug itself four meters deeper into the tidal flats and increased its volume by 400 million m³.

The Norderhever was not formed until the Burchardi flood in 1634, which caused large parts of the island of Alt-Nordstrand to sink into the sea. The current flows through the area that formerly belonged to Alt-Nordstrand and has dug a 20 meter deep channel there over the past 370 years. Since he repeatedly threatens to attack the island bases of Pellworm and Nordstrand, the North Frisians took extensive coastal protection measures on his behalf. In 1906/1907 they connected Nordstrand to the mainland via a dam, the dam broke through the Norderhever, which reunited there with the Heverstrom, and "dried out" this branch of the river. In 1987 the Beltringharder Koog was dyed , again mainly to protect the north beach from the current. The coast guards keep planning a dam between the two islands in order to completely dam the Norderhever, but at the moment it does not endanger Pellworm acutely, so the planning is currently on hold.

Remarks

  1. ^ Frank Spiegel : Volumes of tidal basins in the North Frisian Wadden Sea. In: Federal Environment Agency and national park administrations of Lower Saxony Wadden Sea / Schleswig-Holstein Wadden Sea (ed.): Wadden Sea Environment Atlas. Vol. 1, North Frisian and Dithmarsches Wadden Sea. Eugen Ulmer, Stuttgart 1998/1999, ISBN 3-8001-3491-8 , pp. 46-47.

literature

  • Petra Witez: Final report on the research project MTK 0608 (03 KIS 3160): Programs for the long-term conservation of the Wadden Sea - Prowatt . Edited by the Federal Ministry for Education and Research, Laboe 2002, pp. 91–112.

Coordinates: 54 ° 28 ′ 37.8 ″  N , 8 ° 57 ′ 43.5 ″  E