Severn bore
The Severn bore is a tidal bore seen on the tidal reaches of the River Severn in England.[1] It forms somewhat upstream of Sharpness, and can be seen as far upstream as Maisemore.
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[edit] Formation
The Severn Estuary, which empties into the Bristol Channel, has the second largest tidal range in the world — about 49 feet (15 m),[2][3] exceeded only by the Bay of Fundy. During the highest tides rising water is funneled up the estuary into a wave that travels upstream against the river current at a speed of 8 to 13 miles per hour.[4] The largest bores occur in spring but smaller ones can be seen throughout the year. The Environment Agency publishes timetables and predictions of bore heights on its website.[5] Being the onset of the flood tide it is accompanied by a rapid rise in water level which continues for about one and a half hours after the bore has passed. The Severn bore is not a self-reinforcing solitary wave or soliton but rather a shock wave which is formed because the wave is travelling faster than the wave speed in water above the Bore (see tidal bore for more details).
The largest recorded bore was on 15 October 1966, when it reached a height of 9.2 feet (2.8 m).[6]
[edit] Viewpoints
The Bore is best seen at Stonebench, near Elmore, on the east bank, or at Minsterworth on the west bank. It can also be seen at Over Bridge.
As a natural spectacle, in some respects, the bore is best viewed (and heard) at night when there is less chance of powerboats etc. on it, and/or just in front of it. The engine noise masks the sound of the wave and their wake(s) diminish the spectacle of a single wave rapidly advancing up a smooth river. To a certain extent it can still be seen in the dark and many spectators have powerful torches anyway.
[edit] Surfing
River surfing enthusiasts attempt to surf along on the wave, which can be 2 metres (7 ft) high. The river was first surfed by WWII veteran Jack Churchill, a military cross awardee renowned both for carrying a claymore, and for being the only Allied soldier to kill an enemy with a longbow during the war. He became a surfing enthusiast in his later life and rode the bore on a board he designed himself.[4]
In March 2006, Steve King, a railway engineer from Gloucestershire, attempted to set a record for the longest-ever surf. However, the exact distance of the ride was never verified and the record was later rejected by both the British Surfing Association and Guinness World Records.[7]
In September 2005, several hundred surfers gathered in Newnham on Severn to celebrate 50 years since the first recorded attempt at surfing the Severn bore and to view the première of Longwave by Donny Wright, a historical film documenting the evolution of the sport since its inception in 1955.[1]
The Gloucester Harbour Trustees, as competent harbour authority for this part of the river, have issued safety guidance for surfers, canoeists, small craft and river bank users in relation to the bore.[8]
[edit] References
- ^ a b Rowbotham, Fred (1983) [1964]. Severn Bore. David & Charles. ISBN 0-7153-8508-9.
- ^ "Severn Estuary Barrage" (PDF). UK Environment Agency. 31 May 2006. Archived from the original on 2007-09-30. http://web.archive.org/web/20070930155720/http://www.environment-agency.gov.uk/commondata/acrobat/severnpositionmay2006_1508223.pd. Retrieved 2007-09-03.
- ^ "Coast: Bristol Channel". BBC. http://www.bbc.co.uk/bristol/content/articles/2005/07/04/bristolchannel_feature.shtml. Retrieved 2007-08-27.
- ^ a b Pretor-Pinney, Gavin (2011). The Wavewatcher's companion. London: Bloomsbury. pp. 239–242. ISBN 9781408809761.
- ^ "Severn Bore and Trent Aegir". Environment Agency. http://www.environment-agency.gov.uk/homeandleisure/recreation/31439.aspx. Retrieved 2009-01-12.
- ^ Severn Bore website: Facts
- ^ Tom Wright. "Severn Bore World Surfing Record". http://www.severnsolutions.co.uk/twblog/archive/2006/04/17/severnborerecord. Retrieved 2006-04-17.
- ^ Gloucester Harbour Trustees: Severn Bore guidance
[edit] External links
- The Severn Bore Page
- Severn Bore, Surfing Spot South of Minsterworth on BlooSee Exact location and satellite map
- Severn Bore, Surfing Spot at Over Bridge on BlooSee Exact location and satellite map
- Severn Bore viewing sites (Environment Agency)
- "Severn Bore" (pdf). Gloucester Harbour Trustees. http://www.gloucesterharbourtrustees.org.uk/boresurfing.pdf.
- "Severn Bore and Trent Aegir". Environment Agency. http://www.environment-agency.gov.uk/homeandleisure/recreation/31439.aspx.
- "The Severn Bore". Stroud District Council. http://www.stroud.gov.uk/docs/community/severn_bore.asp.
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