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Definition. Canals are human-made waterways constructed to allow for the passage of boats, ships, and water, often used for transportation and irrigation. These structures play a crucial role in connecting rivers and lakes, facilitating trade, and shaping cultural landscapes by influencing settlement patterns and economic development.
Dec 8, 2022 · Learn what a canal is and how it works. Explore examples of famous canals in the world, including some of the longest and biggest canals in the world.
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canals and inland waterways, natural or artificial waterways used for navigation, crop irrigation, water supply, or drainage.
Despite modern technological advances in air and ground transportation, inland waterways continue to play a vital role and, in many areas, to grow substantially. This article traces the history of canal building from the earliest times to the present day and describes both the constructional and operational engineering techniques used and the major inland waterways and networks throughout the world.
Transport by inland waterways may be on navigable rivers or those made navigable by canalization (dredging and bank protection) or on artificial waterways called canals. Many inland waterways are multipurpose, providing drainage, irrigation, water supply, and generation of hydroelectric power as well as navigation. The lay of the land (topography) and particularly changes in water levels require that many rivers be regulated to make them fully navigable, thus enabling vessels to proceed from one water level to another. The chief regulating method is the lock, the development of which contributed significantly to the Industrial Revolution and the development of modern industrial society.
For many types of commodities, particularly such bulk commodities as grains, coal, and ore, inland waterway transport is still more economical than any other kind of transport. Thus, it is hardly surprising that modernized inland waterways, using the latest navigational aids and traction methods and traversing the great landmasses of North America, Europe, and Asia, play an increasingly important economic role.
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Water and its Varying Forms
Most of the improvement of rivers and construction of artificial waterways in antiquity was for irrigation purposes. In the 7th century bce the Assyrian king Sennacherib built a stone-lined canal 80 km (50 miles) long and 20 metres (66 feet) wide to bring fresh water from Bavian to Nineveh. The work, which included a stone aqueduct 300 metres (330 yards) long, was constructed in one year and three months, according to a plaque that survives on the site. Surprisingly advanced techniques were used, including a dam with sluice gates allowing regulation of the flow of the water stored. The Phoenicians, Assyrians, Sumerians, and Egyptians all constructed elaborate canal systems. The most spectacular canal of this period was probably Nahrawān, 122 metres (400 feet wide) and 322 km (200 miles) long, built to provide a year-round navigation channel from near Sāmarrāʾ to Al-Kūt, using water provided by damming the unevenly flowing Tigris. Many elaborate canals are known to have been built in Babylonia. In Egypt the Nile was dammed to control its floodwaters, and an extensive system of basin irrigation was established. The Persian king Darius in the 5th century bce cut a canal from the Nile River to the Red Sea.
The Romans were responsible for very extensive systems of river regulation and canals in France, Italy, the Netherlands, and Great Britain for military transport. The legions in Gaul canalized one of the mouths of the Rhône River to protect their overseas supply route. In the 1st century bce the Roman consul Marcus Livius Drusus dug a canal between the Rhine and IJssel rivers to relieve the Rhine of surplus water, and the Roman general Corbulo linked the Rhine and Meuse with a canal 37 km (23 miles) long to avoid the stormy North Sea passage from Germany to the coast. Attempting to reclaim the Fens in England, the Romans connected the River Cam with the Ouse by a 13-km (8-mile) canal, the Nene with the Witham by one 40 km (25 miles) long, and the Witham with the Trent by the Fosse Dyke (ditch), still in use.
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In Europe, canal building, which appears to have lapsed after the fall of the Roman Empire, was revived by commercial expansion in the 12th century. River navigation was considerably improved, and artificial waterways were developed with the construction of stanches, or flash locks, in the weirs (dams) of water mills and at intervals along the waterways. Such a lock could be opened suddenly, releasing a torrent that carried a vessel over a shallow place. The commercially advanced and level Low Countries developed a system of canals using the drainage of the marshland at the mouths of the Schelde, Meuse, and Rhine rivers; about 85 percent of medieval transport in the region went by inland waterway.
Because shipping was handicapped where barges had to be towed over the weirs with windlasses or manually, the lock and lock basin were evolved to raise boats from one level to another. Although a primitive form of lock had been in operation as early as 1180 at Damme, on the canal from Brugge to the sea, the first example of the modern pound lock, which impounded water, was probably that built at Vreeswijk, Netherlands, in 1373, at the junction of the canal from Utrecht with the Lek River. Outer and inner gates contained a basin, the water level of which was controlled by alternatively winding up and lowering the gates. In the 15th century the lock-gate system was much improved with the addition of paddles to control the flow of water in and out of the lock chamber through sluices in the gates or sides of the lock.
Commercial needs soon encouraged canal construction in less ideal locations. The Stecknitz Canal, built in Germany (1391–98), ran 34 km (21 miles) from Lake Möllner down to Lübeck, with a fall of 12 metres (40 feet) controlled with four stanches; the canal was later extended south to Lauenburg on the Elbe to establish a link between the Baltic and the North Sea. To deal with a fall from the summit to Lauenburg of 13 metres (42 feet) in 24 km (15 miles), two large locks were built, each capable of holding 10 small barges.
Italy, the other principal commercial region of medieval Europe, also made important contributions to waterway technology. The Naviglio Grande Canal was constructed (1179–1209) with an intake on the Ticino River, a fall of 33.5 metres (110 feet) in 50 km (31 miles) to Abbiategrasso and Milan, the water level being controlled by sluices. To facilitate transport of marble from the quarries for the building of Milan’s cathedral, the canal was linked with an old moat, and in Italy the first pound lock with mitre instead of the earlier portcullis gates was constructed to overcome differences in water levels.
AP Human Geography: Chapter 3 (Spatial Interaction and Spatial Behavior) Movement of peoples, ideas, and commodities (goods bought and sold) within and between areas. Examples: International trade, semitrailers on expressway, radio broadcasts, telephone calls.
- Matt Rosenberg
- Gibraltar. This strait between the Mediterranean Sea and Atlantic Ocean has the United Kingdom's tiny Gibraltar Colony as well as Spain on the north and Morocco and a small Spanish colony on the south.
- Panama Canal. Completed in 1914, the 50-mile long Panama Canal links the Atlantic and Pacific Oceans, reducing the length of the journey between the east and west coasts of the United States by 8000 nautical miles.
- Strait of Magellan. Before the Panama Canal was completed, boats traveling between the U.S. coasts were forced to round the tip of South America. Many travelers risked disease and death by attempting to cross the dangerous isthmus in Central America and catch another boat to their destination to keep from sailing the extra 8000 miles.
- Strait of Malacca. Located in the Indian Ocean, this strait is a shortcut for oil tankers traveling between the Middle East and the oil-dependent nations of the Pacific Rim (especially Japan).
Definition. Canals are artificial waterways constructed for navigation, irrigation, or drainage. They played a crucial role during the Market Revolution by facilitating the movement of goods and people, connecting rural areas with urban centers, and significantly enhancing trade and commerce across the expanding United States.
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A choke point can be a strait, a mountain pass, a tunnel, or even a bridge. Maritime choke points such as certain straits (Hormuz, Malacca, Turkish) and canals (Suez, Panama) maintain tactical and strategic relevance over long periods due to the predominance of world trade on the ocean.
