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A tidal bore (or just bore, or eagre) is a tidal
Tide

Tides are the rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuary water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation ....
 phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travel up a river or narrow bay against the direction of the current. As such, it is a true tidal wave (not to be confused with a tsunami
Tsunami

A is a series of ocean surface wave that is created when a large volume of a body of water, such as an ocean, is rapidly displaced. The Japanese term is literally translated into " harbor wave."...
).

s occur in relatively few locations worldwide, usually in areas with a large tidal range (typically more than between high and low water), and where incoming tides are funneled into a shallow, narrowing river via a broad bay.






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Encyclopedia


Turnagain Bore
A tidal bore (or just bore, or eagre) is a tidal
Tide

Tides are the rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuary water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation ....
 phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travel up a river or narrow bay against the direction of the current. As such, it is a true tidal wave (not to be confused with a tsunami
Tsunami

A is a series of ocean surface wave that is created when a large volume of a body of water, such as an ocean, is rapidly displaced. The Japanese term is literally translated into " harbor wave."...
).

The phenomena

Bores occur in relatively few locations worldwide, usually in areas with a large tidal range (typically more than between high and low water), and where incoming tides are funneled into a shallow, narrowing river via a broad bay. The funnel-like shape not only increases the height of the tide, 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.

Bores take on various forms, ranging from a single breaking wavefront — somewhat like a shock wave
Shock wave

A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field....
 — to ‘undular bores’ comprising a smooth wavefront followed by a train of secondary waves
WAVES

The WAVES were a World War II-era division of the United States Navy that consisted entirely of women. The name of this group is an acronym for "Women Accepted for Volunteer Emergency Service" ; the word "emergency" implied that the acceptance of women was due to the unusual circumstances of the war and that at the end of the war the women...
 (whelps). Large bores can be particularly dangerous for shipping, but also present opportunities for river surfing
River surfing

River surfing is the sport of surfing either standing waves or tidal bores in rivers. Claims for its origins include a 1955 ride of 1.5 miles along the tidal bore of the River Severn....
.

The word bore derives through Old English
Old English language

Old English is an early form of the English language that was spoken and written in parts of what are now England and south-eastern Scotland between the mid-5th century and the mid-12th century....
 from the Old Norse word bára, meaning a wave or swell.

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

Asia

  • Ganges–Brahmaputra, India
    India

    India, officially the Republic of India , is a country in South Asia. It is the List of countries and outlying territories by total area country by geographical area, the List of countries by population country, and the most populous liberal democracy in the world....
    , Bangladesh
    Bangladesh

    , officially the People's Republic of Bangladesh is a country in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south....
  • Indus River
    Indus River

    File:Indian subcontinent CIA.pngThe Indus River is the longest river in Pakistan and the twenty-first largest river in the world, in terms of annual flow, on the Indian Subcontinent....
    , Pakistan
    Pakistan

    Pakistan , officially the Islamic Republic of Pakistan, is a country located in South Asia and borders Central Asia and the Middle East. It has a 1,046 kilometre coastline along the Arabian Sea and Gulf of Oman in the south, and is bordered by Afghanistan and Iran in the west, India in the east and People's Republic of China in th...
  • Qiantang River
    Qiantang River

    The Qiantang River is a southeast China river that originates in the borders of Anhui and Jiangxi provinces and passes through Hangzhou, the capital of Zhejiang province, before flowing into the East China Sea through Hangzhou Bay....
    , China
    China

    China is a Culture of China, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
    ,Tidal bore of Qiantang River which has the world's largest bore, up to 9 meters (30 ft) high, traveling at up to 40 km per hour (25 miles an hour).
  • Batang Lupar or Lupar River, near Sri Aman
    Sri Aman

    Sri Aman is a town, and the capital of the Sri Aman District in Sri Aman Division, Sarawak, east Malaysia.Butuh adam The district population was 66,500, with an ethnic composition of 62.2% Iban people, 22.4% Malay people, 14.1% Han Chinese, and 0.6% Bidayuh. ...
    , Malaysia
    Malaysia

    Malaysia is a federation that consists of States of Malaysia in Southeast Asia with a total landmass of . The capital city is Kuala Lumpur, while Putrajaya is the seat of the federal government....
    . The tidal bore is locally known as benak.


Australia

  • Styx River
    Styx River (Queensland)

    The Styx River is a short river in Queensland. It enters the Broad Sound south of the Port of St Lawrence. The river is crossed by both the Bruce Highway and North Coast railway line, Queensland....
    , Queensland
    Queensland

    Queensland is a States and territories of Australia of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south....
    , Australia
    Australia

    Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
  • Daly River
    Daly River, Northern Territory

    Daly River is the name of a river and a town in the Northern Territory of Australia. At the 2006 Census in Australia, Daly River had a population of 468....
    , Northern Territory
    Northern Territory

    The Northern Territory is a federal states and territories of Australia of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions....
    , Australia
    Australia

    Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....


Europe


United Kingdom

  • River Dee
    River Dee, Wales

    The River Dee is a river. It travels through Wales and England and also forms part of the border between them.The river source in Snowdonia, Wales, flows north via Chester, England, and discharges to the sea into an estuary between Wales and the Wirral Peninsula ....
    , Wales
    Wales

    native_name = Cymru|conventional_long_name = Wales|common_name = Wales|image_flag = Flag of Wales 2.svg|national_motto = ...
     / England
    England

    native_name =|conventional_long_name = England|common_name = England|image_flag = Flag of England.svg|image_coat = England COA.svg|symbol_type = Royal Coat of Arms...
  • River Mersey
    River Mersey

    The River Mersey is a river in North West England. It is around long, stretching from Stockport, Greater Manchester, and ending at Liverpool Bay, Merseyside....
  • River Severn
    River Severn

    The River Severn is the longest river in Great Britain, at . It rises at an altitude of on Plynlimon near Llanidloes, Powys, in the Cambrian Mountains of mid Wales....
    , Wales / England up to high
  • River Trent
    River Trent

    The River Trent is one of the major rivers of England. Its Source is in Staffordshire between Biddulph and Biddulph Moor. It flows through the English Midlands until it joins the River Ouse, Yorkshire at Trent Falls to form the Humber, which empties into the North Sea below Kingston upon Hull and Immingham....
    , (the Aegir) up to high, England and other tributaries of the Humber Estuary
    Humber

    The Humber is a large tidal estuary on the east coast of northern England.The Humber is an estuary formed at Trent Falls, Faxfleet, by the confluence of the tidal River Ouse, Yorkshire and the tidal River Trent....
  • River Parrett
    River Parrett

    The River Parrett is a river flowing through the counties of Dorset and Somerset in South West England. It has its source in the Thorney Mills spring s in the hills around Chedington in Dorset, and flows north west through Somerset and the Somerset Levels to its mouth at Burnham-on-Sea where it flows into the Bridgwater Bay National Nature R...
  • River Welland
    River Welland

    The River Welland is a river in the east of England, 56 km long, and it has been a main waterway across the part of The Fens called "South Holland" for thousands of years....
  • River Kent
    River Kent

    The River Kent is a short river in the county of Cumbria in England. The river originates in hills surrounding Kentmere, and flows for around 20 miles into the north of Morecambe Bay, having passed through Kentmere, Staveley, Cumbria, Burneside, Kendal and Sedgwick, Cumbria on the way....
  • River Great Ouse
    River Great Ouse

    The River Great Ouse is a river in the east of England. It is 150 miles long which makes it the major navigation in East Anglia, and the fourth-Rivers of the United Kingdom#Longest rivers in the United Kingdom....
  • River Ouse, Yorkshire
    River Ouse, Yorkshire

    The River Ouse is a river in North Yorkshire, England. The river is formed from the River Ure at Cuddy Shaw Reach near Linton-on-Ouse, about 6 miles downstream of the confluence of the River Swale with the River Ure....
  • River Eden
    River Eden, Cumbria

    The River Eden is a river that flows through Cumbria, England on its way to the Solway Firth....
  • River Esk
  • River Nith
    River Nith

    The River Nith is the seventh longest river in Scotland. It rises in East Ayrshire, and for the majority of its course flows through Dumfries and Galloway, before spilling into the Solway Firth at Dumfries....


France

The phenomenon is generally named un mascaret in French but some other local names are preferred.
  • Seine
    Seine

    The Seine is a slow flowing major river and commercial waterway within Regions of France of ?le-de-France and Haute-Normandie in France and famous as a romantic backdrop in photographs of Paris, France....
    , 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
    Couesnon

    The Couesnon River is a river running from the D?partement in France of Mayenne in north-western France, forming an estuary at Mont Saint-Michel....
    , Sélune
    Selûne

    Sel?ne is a fictional goddess in the Forgotten Realms setting of Dungeons & Dragons. Also known as Our Lady of Silver and the Moonmaiden, she is the Faer?nian goddess of light, the moon, stars, navigation, navigators, wanderers, questers, and goodly Lycanthrope ....
    , Sée
    See

    The word "see" may refer to:* The act of visual perception* The term "See:" as a form of citation signal* Episcopal see, domain of authority of a bishop...
    .
  • Arguenon
  • Baie de la Frênaye
  • Vire
    Vire

    Vire is a Communes of the Calvados department and the seat of a Cantons of France of the Calvados departments of France in the Basse-Normandie r?gion in France of France....
     
  • Sienne
  • Vilaine
    Vilaine

    The Vilaine is a river in Brittany, in the west of France. The river's source is in the Mayenne D?partement in France , and flows out in the Atlantic Ocean at P?nestin in the Morbihan d?partement ....
    , locally named le mascarin
  • Dordogne
    Dordogne

    Dordogne is a departments of France in central France named after the Dordogne River....
     
  • Garonne
    Garonne

    The Garonne is a river in southwest France and northern Spain, with a length of 575 km ....
     


Norway

  • Saltstraumen
    Saltstraumen

    Saltstraumen is a Sound with a strong Tide located in Nordland 30 km east of the city of Bod?, Norway. The narrow channel connects the outer Saltfjord with its extension, the large Skjerstadfjord....
     near Bodø
    Bodø

    is a List of cities in Norway and a Municipalities of Norway in Nordland Counties of Norway, Norway. It is part of the Salten Districts of Norway....
    , claimed to be the strongest tidal current in the world.


North America

Tidal Bore
* Turnagain arm of Cook Inlet
Cook Inlet

Cook Inlet stretches from the Gulf of Alaska to Anchorage, Alaska in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage....
, Alaska. Up to and 20 km per hour. Most rivers draining into the upper Bay of Fundy
Bay of Fundy

The Bay of Fundy is a Headlands and bays on the Atlantic Ocean coast of North America, on the northeast end of the Gulf of Maine between the Canada Provinces of Canada of New Brunswick and Nova Scotia, with a small portion touching the United States U.S....
 between Nova Scotia
Nova Scotia

Nova Scotia is a Canadian Provinces and territories of Canada located on Canada's southeastern coast. It is the most populous province in Atlantic Canada....
 and New Brunswick
New Brunswick

New Brunswick is one of Canada's three Maritime provinces and is the only Constitution of Canada bilingual province in the federation. The provincial capital is Fredericton....
 have tidal bores. Notable ones include:
  • Petitcodiac River
    Petitcodiac River

    The Petitcodiac River is a Canada river located in southeastern New Brunswick.Because of its colour, it is often nicknamed the "Chocolate River"....
     formerly the highest bore in North America at over high. It was reduced to little more than a ripple due to causeway
    Causeway

    In modern usage, a causeway is a road or railway elevated on a sandbank, usually across a broad body of water or wetland. A transport corridor that is carried instead on a series of arches, perhaps approaching a bridge, is a viaduct....
     construction and extensive silt
    Silt

    Silt is soil or Rock derived granular material of a Particle size between sand and clay. Silt may occur as a soil or as suspended sediment in a surface water body....
    ation.
  • Shubenacadie River
    Shubenacadie River

    The 'Shubenacadie River' is a river in Nova Scotia, Canada.It has a meander length of approximately 72 km from its source at Shubenacadie Grand Lake to its mouth at the historic seaport village of Maitland, Hants County, Nova Scotia on Cobequid Bay, site of the building of the William D....
    , 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 that were in the riverbeds when the bore came in. Tourboat operators offer rafting excursions in summer.
  • The bore is fastest and tallest in some of the smaller rivers that connect to the Bay including the River Hebert
    River Hebert

    The River Hebert is a small tidal river that empties into the Cumberland Basin , contained completely within Cumberland County, Nova Scotia, Nova Scotia....
     and Maccan River
    Maccan River

    The Maccan River is a small tidal river contained completely within Cumberland County, Nova Scotia, Nova Scotia. The river terminates at the confluence with River Hebert at Amherst Point, and empties into the Cumberland Basin ....
     on Cumberland Basin
    Cumberland Basin

    Cumberland Basin is an inlet and northeasternmost part of the Bay of Fundy, located on the border between the Canada provinces of Nova Scotia and New Brunswick....
    , the St. Croix
    St. Croix River (Nova Scotia)

    The St. Croix River is a river in Nova Scotia entirely contained in Hants County and Halifax County, Nova Scotia Counties. Its headwaters are Panuke Lake....
    , Herbert and Kennetcook
    Kennetcook River

    The Kennetcook River is a river that flows through Hants County, Nova Scotia. From headwaters near the mouth of the Shubenacadie River, the Kennetcook traverses about 45 kilometres of mostly rural terrain, discharging into the Avon River, Nova Scotia at Windsor, Nova Scotia....
     Rivers in the Minas Basin
    Minas Basin

    The Minas Basin is an inlet of the Bay of Fundy and a sub-basin of the Fundy Basin located in Nova Scotia, Canada....
    , and the Salmon River
    Salmon River (Nova Scotia)

    The Salmon River is a Canada river in central Nova Scotia's Colchester County, Nova Scotia.Rising in the Cobequid Hills in the central-northeastern part of the county, the river descends through a broad glacial valley at the head of Cobequid Bay, the eastern extremity of the Bay of Fundy....
     in Truro.


South America

  • Amazon River
    Amazon River

    The Amazon River of South America is the list of rivers by length in the world by volume, with a total river flow greater than the next top eight largest rivers combined....
     in Brazil
    Brazil

    Brazil , officially the Federative Republic of Brazil , is a country in South America. It is the List of countries and outlying territories by total area country by geographical area, occupying nearly half of South America, the List of countries by population country, and the fourth most populous democracy in the world....
     and Orinoco River in Venezuela
    Venezuela

    Venezuela , officially the Bolivarian Republic of Venezuela , is a country on the northern coast of South America.The country comprises a continental mainland and numerous islands located off the Venezuelan coastline in the Caribbean Sea....
    , up to high, running at up to 20 km/h (13 miles per hour). It is known locally as the pororoca
    Pororoca

    The pororoca is a tidal bore, with waves up to 4 meters high that travel as much as 13 kilometers inland upstream on the Amazon River. Its name comes from the indigenous Tupi language, where it translates into "great destructive noise"....
    .
  • Mearim River
    Mearim River

    The Mearim River is a river in Maranh?o state of northern Brazil. The river originates in the southern part of Maranh?o, and drains north into the Ba?a de S?o Marcos, an estuary that also receives the Pindar? River and Graja? River rivers, which are sometimes considered tributaries of the Mearim....
     in Brazil.
  • Araguari River in Brazil.

See also

  • 1812 New Madrid earthquake (in the US) (causing the Mississippi River to flow backwards)
  • Hydraulic jump
    Hydraulic jump

    A hydraulic jump is a phenomenon in the science of hydraulics which is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface....
  • Tidal race
    Tidal race

    Tidal race is a natural occurrence whereby a fast moving tide passes through a constriction resulting in the formation of waves, eddy and hazardous ocean current....
  • Tonlé Sap
    Tonlé Sap

    The Tonl? Sap , i.e., large body of water is a combined lake and river system of huge importance to Cambodia. It is the largest freshwater lake in South East Asia and is an ecological hot spot that was designated as a UNESCO biosphere in 1997....
     (lake and river system in Cambodia) (where monsoon flooding causes the river to flow backwards)
  • Undular bore wave


External links

  • , USC
    University of Southern California

    The University of Southern California is a private university, nonsectarian, research university located in the University Park, Los Angeles, California neighborhood in Los Angeles, California, California, United States....
     Tsunami Research Group
  • in Journal La Houille Blanche, No. 3, pp. 103-114]
  • in Journal of Coastal Research, Vol. 24, No. 4, pp. 999-1007 (DOI: 10.2112/06-0688.1)