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Saturday, December 6

Surfing China: Tidal Bore River Wave





Location - Qiantang River in Hangzhou China.

Jamie Sterling and Reno Makani compete in the first ever Red Bull Qiantang Surfing Shoot Out. We got to explore the Great Wall of China. Learned about the countries biodiversities and it's amazing culture. We ends up making it to the finals and placing second and received a Silver medal woot woot!

Brief educational information about tidal bores-
  
Bores occur in relatively few locations worldwide, usually in areas with a large tidal range (typically more than 6 metres (20 ft) between high and low water) and where incoming tides are funneled into a shallow, narrowing river or lake via a broad bay. The funnel-like shape not only increases the tidal range, but it can also decrease the duration of the flood tide, down to a point where the flood appears as a sudden increase in the water level. A tidal bore takes place during the flood tide and never during the ebb tide. 


A tidal bore may take on various forms, ranging from a single breaking wavefront with a roller – somewhat like a hydraulic jump – to undular bores, comprising a smooth wavefront followed by a train of secondary waves known as whelps. Large bores can be particularly unsafe for shipping but also present opportunities for river surfing like what we did in China during the 2012 Red Bull Qiantang Shoot Out.

Two key features of a tidal bore are the intense turbulence and turbulent mixing generated during the bore propagation, as well as its rumbling noise. The visual observations of tidal bores highlight the turbulent nature of the surging waters. The tidal bore induces a strong turbulent mixing in the estuarine zone, and the effects may be felt along considerable distances. The velocity observations indicate a rapid deceleration of the flow associated with the passage of the bore as well as large velocity fluctuations. A tidal bore creates a powerful roar that combines the sounds caused by the turbulence in the bore front and whelps, entrained air bubbles in the bore roller, sediment erosion beneath the bore front and of the banks, scouring of shoals and bars, and impacts on obstacles. The bore rumble is heard far away because its low frequencies can travel over long distances. The low-frequency sound is a characteristic feature of the advancing roller in which the air bubbles entrapped in the large-scale eddies are acoustically active and play the dominant role in the rumble-sound generation. 

The word bore derives through Old English from the Old Norse word bára, meaning "wave" or "swell".


Rivers with tidal bores
Rivers that have been known to exhibit bores include those listed below

Asia
Ganges–Brahmaputra, India and Bangladesh
Indus River, Pakistan
Sittaung River, Burma
Qiantang River, China, which has the world's largest bore, up to 9 metres (30 ft) high, traveling at up to 40 kilometres (25 mi) per hour
Batang Lupar or Lupar River, near Sri Aman, Malaysia. The tidal bore is locally known as benak.
Bono, Kampar River, Indonesia. The phenomenon is feared by the locals to sink ships. It is reported to break up to 130 kilometres (81 mi) inland.

Australia
Styx River, Queensland
Daly River, Northern Territory

Europe
River Shannon, Limerick, Ireland: 21 September 2013

United Kingdom

The Trent Aegir seen from West Stockwith, Nottinghamshire, 20 September 2005

The Trent Aegir at Gainsborough, Lincolnshire, 20 September 2005
River Dee, Wales and England
River Mersey
The Severn bore on the River Severn, Wales and England, up to 2 metres (7 ft) high
The Trent Aegir on the River Trent, England, up to 1.5 metres (5 ft) high. Also other tributaries of the Humber Estuary.
River Parrett
River Welland
The Arnside Bore on the River Kent
River Great Ouse
River Ouse, Yorkshire. Like the Trent bore, this is also known as "the Aegir".
River Eden
River Esk
River Nith
River Lune, Lancashire
River Ribble, Lancashire

France
The phenomenon is generally named un mascaret in French.[18] but some other local names are preferred.
Seine, locally named la barre, had a significant bore until the 1960s. Since then, it has been practically eliminated by dredging and river training.
Baie du Mont Saint Michel including Couesnon, Sélune, and Sée
Arguenon
Baie de la Frênaye
Vire
Sienne
Vilaine, locally named le mascarin
Dordogne
Garonne
Papua New Guinea
Fly River

North America
United States
Tidal bore on the Petitcodiac River
The Turnagain arm of Cook Inlet, Alaska. Up to 2 metres (7 ft) and 20 km/h (12 mph).
The Savannah River up to 10 miles (16 km) inland.
Small tidal bores, only a few inches in height, have been observed advancing up tidal bayous on the Mississippi Gulf Coast.

Canada
Most rivers draining into the upper Bay of Fundy between Nova Scotia and New Brunswick have tidal bores. Notable ones include:
The Petitcodiac River, formerly had the highest bore in North America at over 2 metres (6.6 ft) in height but causeway construction between Moncton and Riverview in the 1960s led to subsequent extensive sedimentation which reduced the bore to little more than a ripple. After considerable political controversy, the causeway gates were opened on April 14, 2010, as part of the Petitcodiac River Restoration Project and the tidal bore began to grow again. The restoration of the bore has been sufficient enough that in July 2013, professional surfers rode a one metre high wave 29 km up the Petitcodiac River from Belliveau Village to Moncton to establish a new North American record for continuous surfing.
The Shubenacadie River, also off the Bay of Fundy in Nova Scotia. When the tidal bore approaches, completely drained riverbeds are filled. It has claimed the lives of several tourists who were in the riverbeds when the bore came in.Tour boat operators offer rafting excursions in the summer.
The bore is fastest and highest on some of the smaller rivers that connect to the bay including the River Hebert and Maccan River on the Cumberland Basin, the St. Croix, Herbert and Kennetcook Rivers in the Minas Basin, and the Salmon River in Truro.

Mexico
Historically, there was a tidal bore on the Sea of Cortez in Mexico at the entrance of the Colorado River. It formed in the estuary about Montague Island and propagated upstream. Once very strong, later diversions of the river for irrigation have weakened the flow of the river to the point the tidal bore has nearly disappeared.

South America
Amazon River in Brazil and Orinoco River in Venezuela, up to 4 metres (13 ft) high, running at up to 13 mph (21 km/h). It is known locally as the pororoca.
Mearim River in Brazil
Araguari River in Brazil

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