Tidal bore

A tidal wave is a wave that is triggered by the tide and moves from an estuary from upstream. It is found in the lower reaches of virtually all rivers that flow into seas with significant tidal range. Particularly striking are extreme forms, the so-called Boren (Indian: Flood ). Tidal waves should not be confused with tsunamis. ( These are triggered by other phenomena and are not tied to river mouths. )

Description

At high tide, water is forced into a river and there is a wave or multiple waves propagating against the flow direction of the river and the water surface elevations are above the still water level.

The extreme form, the Bore is observed only in a few places around the world. It is limited to areas where the tidal range is very large. Certain tides and mouth shapes can favor their formation. Boren can be followed either as a single breaking wave occur or of several smaller waves. Larger specimens can be dangerous for shipping, but also provide a challenge for surfers dar.

Rivers where tidal waves occur

It is recognized internationally for a total of 67 places the occurrence of Boren.

Asia

  • Brahmaputra, Bangladesh
  • Kampar, Sumatra, Indonesia
  • Indus, Pakistan
  • Qiantang River, China, where the 8 to 9 meters world's largest tidal bore, called the "Silver Dragon " occurs. Late August or early September, the Bore flows into the Bay of Hangzhou and rolls the Qiantang River in Haining up direction at a speed of 25-40 kilometers per hour.

South America

  • Amazon is up to 5 meters high and up to 65 kilometers per hour in the spring in spring tide. The shaft, which is called because of their loud rumblings from the Indians Pororoca (large noise), extending up to 800 km circulated upstream ( Óbidos ).

North America

  • Petitcodiac in the Bay of Fundy, New Brunswick, Canada, formerly the largest tidal wave of North America, up to 7.5 meters high. After the construction of a road embankment in 1968 and the silting up of the river caused by him she is today but much smaller.
  • Shubenacadie, in the Bay of Fundy, Nova Scotia
  • The Turnagain Arm of Cook Inlet, Alaska, up to two feet high, and twenty kilometers per hour

Europe

  • Dee, Wales / England
  • Mersey, England
  • Severn, Wales / England up to 2 meters high
  • Trent, England and other feeds the Humber
  • Parrett, England
  • Kent, England
  • Great Ouse, England
  • Eden, England
  • Esk, Scotland
  • Gironde and the Garonne and Dordogne, France
  • On the Seine ( France ), there was until the 1960s a major tidal wave ( " le mascaret " ), but which was virtually destroyed by dredging
  • Weaker tidal currents on the Weser (up Vegesack visible) and the same
  • After almost every low tide on the river Ems

Oceania

  • Styx, Queensland, Australia
  • Daly, Northern Territory, Australia
Brahmaputra River Indus River Haining City Amazon River Petitcodiac River River Mersey River Trent River Great Ouse Dordogne (river)
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