..... Click the link for more information. of England and the Zuider Zee Zuider Zee (zī`dər zē, zā, Du. zoi`dər zā), former shallow inlet of the North Sea, c.
..... Click the link for more information. in the Netherlands were drained. Canals can be used for flood control by diverting water from threatened areas into storage basins or to other outlets. In some cases canals are used to generate electricity; the Moscow-Volga Canal is used for this purpose.
Navigation canals developed after irrigation canals and for a long time were level, shallow cuts or had inclined planes up which vessels were hauled from one level to the next; locks (see lock, canal lock, canal, stretch of water enclosed by gates, one at each end, built into a canal or river for the purpose of raising or lowering a vessel from one water level to another. A lock may also be built into the entrance of a dock for the same purpose.
..... Click the link for more information. ) developed separately in China (10th cent.) and Europe (Holland; 13th cent.). Over the years canals have been expanded in width and depth in order to accommodate larger craft, and they have, in some cases, been constructed to form bridges or to pass through tunnels to overcome topographic difficulties. Movement on canals was long accomplished by animal tows or by poling; in the 20th cent. mechanized tows and self-propelled barges appeared.
The Grand Canal Grand Canal, Chinese Da Yunhe [large transit river], longest in the world, extending c.1,000 mi (1,600 km) from Beijing to Hangzhou, E China, and forming an important north-south waterway on the North China Plain. The canal was started in the 6th cent. B.C.
..... Click the link for more information. of China (the longest in the world) was completed in the 13th cent. and is the most notable of the early canals. France, Belgium, Holland, and Germany were the first in Europe to develop inland waterway systems by using canals to connect rivers; these countries now have a dense network of waterways (see Rhine Canals Rhine Canals. Among the chief canals linking the Rhine with other river systems are the Rhine-Rhône Canal, 217 mi (349 km) long (built 1784–1833, now unimportant), connecting with the Rhône River through the Saône River; the Rhine-Marne Canal,
..... Click the link for more information. ; Midland Canal Midland Canal, Ger. Mittelland Kanal, artificial waterway system of Germany, extending eastward c.200 mi (320 km) along the North German plain from the Dortmund-Ems Canal, Germany, to Magdeburg, Germany, on the Elbe River.
..... Click the link for more information. ). Canal building was widespread in the 18th and 19th cent. During that period England developed an elaborate canal network, and there was also a canal-building boom in the United States in the 19th cent., especially after the completion of the Erie Canal Erie Canal, artificial waterway, c.360 mi (580 km) long; connecting New York City with the Great Lakes via the Hudson River. Locks were built to overcome the 571-ft (174-m) difference between the level of the river and that of Lake Erie.
..... Click the link for more information. . However, the rise of railroads brought a decline in the building and use of canals as inland waterways. Canals have been built to shorten sea voyages or to make them less hazardous, e.g., the Suez Canal Suez Canal, Arab. Qanat as Suways, waterway of Egypt extending from Port Said to Port Tawfiq (near Suez) and connecting the Mediterranean Sea with the Gulf of Suez and thence with the Red Sea. The canal is somewhat more than 100 mi (160 km) long.
..... Click the link for more information. , the Panama Canal Panama Canal, waterway across the Isthmus of Panama, connecting the Atlantic (by way of the Caribbean Sea) and Pacific oceans, built by the United States (1904–14) on territory leased from the republic of Panama .
..... Click the link for more information. , and the Kiel Canal Kiel Canal, artificial waterway, 61 mi (98 km) long, in Schleswig-Holstein, N central Germany, connecting the North Sea with the Baltic Sea. At sea level, the canal extends from Kiel on the Baltic to Brunsbüttelkoog at the mouth of the Elbe River.
..... Click the link for more information. . Canals improve conditions on natural waterways by bypassing falls (the Welland Ship Canal Welland Ship Canal, 27.6 mi (44.4 km) long, SE Ont., Canada, connecting Lake Ontario with Lake Erie and bypassing Niagara Falls. Built between 1914 and 1932 by Canada to replace a canal opened in 1829, it can accommodate (minimum depth 27 ft/8 m) the largest lake
..... Click the link for more information. ), shallows, or swift currents (the Sip Canal in the Danube River's Iron Gate gorge). Canals may provide inland cities with direct access to the sea (the Manchester Ship Canal Manchester Ship Canal, 35.5 mi (57 km) long with a minimum depth of 28 ft (8.5 m), connecting Manchester, W England, with the Mersey estuary at Eastham, above Birkenhead. Begun in 1887, it was opened in 1894 and changed Manchester from a river port to a seaport.
..... Click the link for more information. ), or shorten the distance between cities (the Albert Canal Albert Canal, waterway, c.80 mi (130 km) long, N Belgium, from the Meuse River to the Scheldt River; constructed 1930–39. The canal connects the important industrial region around Liège with the port of Antwerp , Belgium.
..... Click the link for more information. ). In the 20th cent. canals regained importance, as modern technology provided the means to overcome greater topographic obstacles and facilitated the construction of larger canals and the expansion of existing ones. The Great Lakes Great Lakes, group of five freshwater lakes, central North America, creating a natural border between the United States and Canada and forming the largest body of freshwater in the world, with a combined surface area of c.95,000 sq mi (246,050 sq km).
..... Click the link for more information. –Saint Lawrence Seaway Saint Lawrence Seaway, international waterway, 2,342 mi (3,769 km) long, consisting of a system of canals, dams, and locks in the St. Lawrence River and connecting channels between the Great Lakes; opened 1959.
..... Click the link for more information. system, opened to navigation in 1959, is the world's longest deep-draft inland waterway. Including six short canals with a total length of less than 60 nautical mi (110 km), it extends from the Atlantic Ocean to Duluth, Minn. on Lake Superior, a distance of more than 2,340 mi (3,700 km), providing large oceangoing vessels passage into central North America.
Bibliography
See C. Hadfield, World Canals (1986); R. Spangenburg and D. Moser, The Story of America's Canals (1992); R. E. Shaw, Canals for a Nation: The Canal Era in the United States, 1790–1860 (1993); J. M. Bracken, American Waterways: The Role of Canals in America (1997).
canal
)
canal
canal [kə′nal]
Canal
An artificial open channel usually used to convey water or vessels from one point to another. Canals are generally classified according to use as irrigation, power, flood-control, drainage, or navigation canals or channels. All but the last type are regarded as water conveyance canals.
Canals may be lined or unlined. Linings may consist of plain or reinforced concrete, cement mortar, asphalt, brick, stone, buried synthetic membranes, or compacted earth materials. Linings serve to reduce water losses by seepage or percolation through pervious foundations or embankments and to lessen the cost of weed control. Concrete and other hard-surface linings also permit higher water velocities and, therefore, steeper gradients and smaller cross sections, which may reduce costs and the amount of right-of-way required.
Navigation canals are artificial inland waterways for boats, barges, or ships. A canalized river is one that has been made navigable by construction of one or more weirs or overflow dams to impound river flow, thereby providing navigable depths. Locks may be built in navigation canals and canalized rivers to enable vessels to move to higher or lower water levels. A lock is a chamber equipped with gates at both upstream and downstream ends. Water impounded in the chamber is used to raise or lower a vessel from one elevation to another. The lock chamber is filled and emptied by means of filling and emptying valves and a culvert system usually located in the walls and bottom of the lock. See Transportation engineering, Water supply engineering
How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content.
| ?Page tools | ||
|---|---|---|
|