AskDefine | Define eagre

Dictionary Definition

eagre n : a high wave (often dangerous) caused by tidal flow (as by colliding tidal currents or in a narrow estuary) [syn: tidal bore, bore, aegir, eager]

User Contributed Dictionary

English

Pronunciation

Noun

  1. a tidal bore

Quotations

  • A large wave like an eagre, diverging from its bow, was extending to either bank, swamping the tules and threatening to submerge the lower levees. — Bret Harte, A Protegee of Jack Hamlin's

Extensive Definition

A tidal bore (or just bore, or eagre) is a tidal 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).
Bores occur in relatively few locations worldwide, usually in areas with a large tidal range (typically more than 20 feet (6 m) 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 — effectively a shock wave — to ‘undular bores’ comprising a smooth wavefront followed by a train of solitary waves (solitons). Larger bores can be particularly dangerous for shipping, but also present opportunities for river surfing.
The word bore derives through Old English from the Old Norse word bára, meaning a wave or swell.
Rivers that have been known to exhibit bores include those listed below.

Asia

South America

North America

  • Petitcodiac River in the Bay of Fundy, New Brunswick, Canada, formerly the highest bore in North America, over 2 metres (6 ft) high. It was reduced to little more than a ripple due to causeway construction and extensive siltation.
  • Shubenacadie River, also off the Bay of Fundy, Nova Scotia. When the tidal bore approaches, completely drained riverbeds are filled. The bore is fastest and tallest in some of the smaller rivers that connect to the Bay. It has claimed the lives of several tourists that were in the riverbeds when the bore came in.
  • Turnagain arm of Cook Inlet, Alaska. Up to 2 meters (6 ft) and 20 km per hour.
Most rivers off the upper Bay of Fundy between Nova Scotia and New Brunswick have tidal bores. These include the River Hebert, Kennetcook River and Maccan River, the St. Croix River in the Minas Basin, and the Salmon River in Truro.

Europe

United Kingdom

France

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

Norway

eagre in Bengali: জলোচ্ছ্বাস
eagre in German: Gezeitenwelle
eagre in Spanish: Macareo (física)
eagre in French: Mascaret
eagre in Galician: Macareu
eagre in Ido: Baro-fluxo
eagre in Italian: Mascheretto
eagre in Hungarian: Torlóár
eagre in Dutch: Getijdegolf
eagre in Japanese: 海嘯
eagre in Norwegian: Tidevannsbølge
eagre in Norwegian Nynorsk: Tidvassbølgje
eagre in Portuguese: Macaréu
eagre in Russian: Бор (волна)
eagre in Finnish: Vuorovesiporras
eagre in Swedish: Bore (hydrologi)
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