waterway, natural or artificial navigable inland body of water, or system of interconnected bodies of water, used for transportation, may include a lake, river, canal, or any combination of these. The existence of waterways has been an important factor in the development of regions, for the waterways have served first as paths of exploration and new settlement and later as avenues of commerce and trade. Although slower than rail, road, and air transport, water shipping is less expensive and accommodates such bulk cargoes as coal, ores, grain, and lumber. Navigation on waterways may be improved by the construction of canals, dams, locks, levees, and dikes; channeling straightens and shortens water courses, and dredging deepens the channel. Waterways vary in size from shallow barge-carrying rivers and canals to the deep seaways that accommodate oceangoing vessels. Waterways are often of international importance, either because they border or run through more than one country or because other nations wish to use them for trade; a number of these waterways have been internationalized. For purposes of navigation, irrigation, and flood control, humans have changed the natural flow of waterways. The consequences of such changes have often led to excessive erosion or an increase in flooding.

Artificial waterway built for transportation, irrigation, water supply, or drainage. The early Middle Eastern civilizations probably first built canals to supply drinking and irrigation water. The most ambitious navigation canal was a 200-mi (320-km) construction in what is now Iraq. Roman canal systems for military transport extended throughout northern Europe and Britain. The most significant canal innovation was the pound lock, developed by the Dutch c. 1373. The closed chamber, or pound, of a lock is flooded or drained of water so that a vessel within it is raised or lowered in order to pass between bodies of water at different elevations. Canals were extremely important before the coming of the railroad in the mid-19th century. Among the significant waterways in the U.S. were the Erie Canal, several canals linking the Great Lakes, and one connecting the Great Lakes to the Mississippi River. Modern waterway engineering enables larger vessels to travel faster by reducing delays at locks. See also Grand Canal, Panama Canal, Suez Canal.

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End portion of the alimentary canal, distinguished from the rectum by the transition from an internal mucous membrane layer to one of skinlike tissue and by its narrower diameter. Waste products move from the rectum to the anal canal. The human anal canal is 1–1.5 in. (2.5–4 cm) long and has three parts: upper, with longitudinal folds (rectal columns); lower, with involuntary and voluntary constrictive muscles (sphincters) to control discharge of feces; and the anal opening itself. Enlargements of the ends of rectal and anal veins are called hemorrhoids.

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Canal, southeastern Ontario, Canada. Linking Lake Huron with Lake Ontario, the canal extends from the southeastern shore of Georgian Bay up the Severn River to Lake Simcoe, connects several lakes of the Kawartha Lake region to Rice Lake, and passes down the Trent River to the Bay of Quinte and Lake Ontario. Its 242-mi (389-km) main course consists of 33 mi (53 km) of man-made channels and 42 locks. Construction began in 1833. The waterway once served a busy lumber trade; it is now a popular tourist attraction.

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Ship canal, Isthmus of Suez, Egypt. Connecting the Red Sea with the eastern Mediterranean Sea, it extends 101 mi (163 km) from Port Said to the Gulf of Suez and allows ships to sail directly between the Mediterranean and the Indian Ocean. Built by the French-owned Suez Canal Co., it was completed in 1869 after a decade of construction. Its ownership remained largely in French and British hands until Egypt nationalized it in 1956, setting off an international crisis (see Suez Crisis). It has a minimum width of 179 ft (55 m) and a depth of about 40 ft (12 m) at low tide. Though protected by international treaty, the canal has been closed twice. The first closing was during the Suez Crisis. The canal was closed again by the Six-Day War (1967) and remained inoperative until 1975. It is one of the world's most heavily used shipping lanes.

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Lock-type canal, Panama. Extending across the Isthmus of Panama, it connects the Atlantic and Pacific oceans. It is about 50 mi (82 km) long from deepwater to deepwater, with an average depth of 43 ft (13 m). The width varies between 500 to 1,000 ft (150 to 300 m). In 1881 a French company began constructing the canal, but the enterprise collapsed in 1889. Under a 1903 treaty Panama granted the U.S. the Panama Canal Zone and the rights to build and operate a canal. Work began in 1904; facing enormous obstacles, George Washington Goethals directed the construction from 1907, and the canal opened on Aug. 15, 1914. The canal enabled ships traveling between the two oceans to avoid the lengthy circumnavigation of South America and was a boon to world commerce. After disputes over sovereignty, a 1977 treaty provided for Panama to take control of the canal by 2000; it did so in 1999. Except for small craft, no vessel can pass through the canal under its own power. Ships are towed by electric locomotives, and it generally takes 15–20 hours to complete the passage (including waiting time). Sets of double locks enable ships to pass in opposite directions simultaneously.

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Deep fjord, southeastern Alaska, U.S. An important gateway to the Klondike region, it is 80 mi (129 km) long and 6 mi (10 km) wide. The northernmost fjord to penetrate the Coast Mountains, it was named in 1794 by Capt. George Vancouver for his birthplace, King's Lynn, Eng.

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Neighbourhood in Niagara Falls, N.Y., the site of the worst environmental disaster involving chemical wastes in U.S. history. Originally the site of an abandoned canal, it became a dumping ground for nearly 22,000 tons of chemical waste in the 1940s and '50s. The canal was later filled in, and housing was built on it. The leakage of toxic chemicals into these homes was detected in 1978, and residents were discovered to have a high incidence of chromosome damage. After their evacuation, 1,300 former residents obtained a $20 million settlement from the dumping company and the city. In the early 1990s New York state ended its cleanup and declared parts of the area safe for residence.

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Series of waterways in northern China that link Hangzhou with Beijing. Some 1,085 mi (1,747 km) in length, it is the world's longest man-made waterway. It was build to enable successive Chinese regimes to transport surplus grain from the agriculturally rich Yangtze (Chang) and Huai river valleys to feed the capital cities and large standing armies in the north. The oldest portion, in the south, may date from the 4th century BC. Expanded over the centuries, it continues to be used today for shipping and irrigation.

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Historic waterway, northern U.S. It stretches from Buffalo, N.Y., on Lake Erie to Albany, N.Y., on the Hudson River. Commissioned by Gov. DeWitt Clinton of New York, it opened in 1825. It connected the Great Lakes with New York City and contributed greatly to the settlement of the Midwest, allowing for the transport of people and supplies. Enlarged several times, the canal is 363 mi (584 km) long, 150 ft (46 m) wide, and 12 ft (3.6 m) deep. Now used mainly for pleasure boating, it is part of the New York State Canal System.

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Park, eastern U.S. It consists of the former Chesapeake and Ohio Canal, a waterway running along the Potomac River between Washington, D.C., and Cumberland, Md. The canal, which extends 185 mi (297 km), was built beginning in the 1820s. Competition from the railroads later caused its economic decline. The canal was purchased in 1938 by the U.S. government; it was restored and established as a historical park in 1971.

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or Panama Canal Zone

Strip of territory, a historic administrative entity in Panama over which the U.S. formerly exercised jurisdictional rights (1903–79). The zone came into being in 1904 when Panama granted the U.S., in return for annual payments, sole right to operate and control the Panama Canal, including a strip of land 10 mi (16 km) wide along the canal extending from the Atlantic to the Pacific Ocean and bisecting the Isthmus of Panama. The zone was abolished by treaty in 1979, and civil control of the territory was returned to Panama. By the same treaty a commission under joint U.S.-Panamanian ownership was established to operate the canal until the year 2000, when Panama assumed full control.

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Series of rivers and canals, western Russia. The navigable system links the Volga River with the Baltic Sea and includes the Neva River, a canal along the southern shore of Lake Ladoga, and the Sheksna River past Cherepovets through the Rybinsk Reservoir. Its total length is some 685 mi (1,100 km). The system was completed in 1964, replacing the antiquated Mariinsk Canal system using the same route that had been constructed originally in the 18th century and later several times enlarged and improved. The system includes seven automatic locks.

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A waterway is any navigable body of water. These include rivers, lakes, seas, oceans, and canals. In order for a waterway to be navigable, it must meet several criteria:

• The waterway must be deep enough to allow the draft depth of the vessels using it;
• The waterway must be wide enough to allow passage for the beam width of the vessels using it;
• The waterway must be free of barriers to navigation such as waterfalls and rapids, or have a way around them (such as canal locks);
• The current of the waterway must be mild enough to allow vessels to make headway.

Vessels using waterways vary from small animal-drawn barges to immense ocean tankers and ocean liners, such as cruise ships.

Canals

Canals are waterways that are constructed to provide a new path of travel for vessels (as opposed to improving a natural waterway along its current course). At one time, canals were built mostly for small wooden barges drawn by horses or other draft animals. Today, major canals are built to allow passage of large ocean-going vessels (see Ship canal).

Tidal waterway

A tidal waterway is one open to the sea and far enough downstream (close enough to the sea) to be subject to twice-daily (or daily, depending on the local tides) reversals of flow and variation in depth. Non-tidal waterways are either far enough upstream to be beyond tidal effects, or are separated from the sea or the tidal stretch of the same waterway by a barrier (usually a navigation lock).

In actuality, every body of any liquid on the face of the Earth is subject to tides—even a bird bath. However, only bodies of water susceptible to tidal changes noticeable to humans are included in the customary definition.

See also

• List of waterways
• List of countries by waterways length
• International waterway
• Pacific Ocean
• Indian Ocean
• Arabian Sea
• Great Lakes
• Strait of Magellan
• Cape of Good Hope
• Panama Canal
• Suez Canal
• Erie Canal
• Tennessee-Tombigbee Waterway
• Cape Cod Canal
• Saint Lawrence Seaway
• Great Lakes Waterway
• Intracoastal Waterway
• Ecocanal Waterway