Tidal wave

from Wikipedia, the free encyclopedia
Tidal wave on the Upper Cook Inlet in Alaska
Tide wave in Hangzhou Bay

A tidal wave is a wave that is caused by the tide and moves upstream from an estuary . It is found on the lower reaches of practically all rivers that flow into seas with a clear tidal range. Particularly noticeable are extreme forms called strikers or bores (from English bore , "boring, drilling"). Tidal waves shouldn't be confused with tsunamis . (These are triggered by other phenomena and are not tied to estuaries.)


At high tide , water is pushed into a river and a wave or several waves are created which run against the direction of flow of the river and whose water level deflections are above the calm water level.

The extreme form, the flood surf or Bore, is only observed in a few places worldwide. It is restricted to areas where the tidal range is particularly large. Certain tides and mouth shapes can promote their formation. Boren can either appear as a single breaking wave or be followed by several smaller waves. Larger specimens can be dangerous for shipping , but also pose a challenge for surfers .

Rivers on which tidal waves occur

World map: Coasts with a tidal range of more than 4 meters

Boren is known to occur in 67 places worldwide.


South America

  • Amazonas , with low water flow in February / March at spring tide, can grow up to 5 meters high and up to 65 kilometers per hour. The wave, called Pororoca (great noise) by the Indians because of its loud rumbling , rolls up to 800 km (town of Óbidos ) upstream. It has been surfed on since 1996.

North America

wave on the Petitcodiac River


Surfer on the Severn tidal
wave in UK

On the Seine (France) there was a significant tidal wave (“le mascaret”) until the 1960s, but it was practically destroyed by dredging. Weaker tidal currents on the Weser ( visible as far as Bremen- Vegesack ) and the Elbe as well as on the Ems after almost every low water . On the Ems it was referred to as the Bare in the 19th century .

Australia and Oceania

Web links

Commons : Tidal Wave  - Collection of images, videos and audio files

Individual evidence

  1. a b Brockhaus: What is not in the lexicon 2008
  2. 9 meter mega-wave pulls people into the river , wetter.at, from August 18, 2014 (video)
  3. Surfing the pororoca. ( Memento of the original from April 17, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. amazingstuff.co.uk, July 26, 2011. @1@ 2Template: Webachiv / IABot / amazingstuff.co.uk