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Aqueduct (structure)

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This redirect is about conduits used for water supply. For bridges used by boats, see navigable aqueduct. For other uses, see aqueduct (disambiguation).
Pont du Gard, France, a Roman aqueduct built circa 19 BC. It is one of France's top tourist attractions and a World Heritage Site.

An aqueduct ('a-kwe-,dekt) is a water supply or navigable channel (conduit) constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose.[1] In a more restricted use, aqueduct (occasionally water bridge) applies to any bridge or viaduct that transports water—instead of a path, road or railway—across a gap. Large navigable aqueducts are used as transport links for boats or ships. Aqueducts must span a crossing at the same level as the watercourses on each side. The word is derived from the Latin aqua ("water") and ducere ("to lead").

Ancient aqueducts

Mathur Aqueduct, India

Although particularly associated with the Romans, aqueducts were devised much earlier in Greece and the Near East and Indian subcontinent, where peoples such as the Egyptians and Harappans built sophisticated irrigation systems. Roman-style aqueducts were used as early as the 7th century BC, when the Assyrians built an 80 km long limestone aqueduct, 10 m high and 300 m wide, to carry water across a valley to their capital city, Nineveh.

In the new world, when the Aztec capital of Tenochtitlán was discovered in the middle of the second millennium, it was watered by two aqueducts. Water ran down to the city from the mountains through one while the other was cleaned and maintained.

Indian People

The Indian subcontinent is believed to have some of the earliest aqueducts. Evidence can be found at the sites of present day Hampi, Karnataka. The massive aqueducts near river Tungabhadra supplying irrigation water were once 15 miles (24 km) long[2]. The water ways supplied water to royal bath houses.

Oman

Main article: Falaj

In Oman from the Iron Age Period (found in Salut, Bat and other sites) a system of underground aqueducts called Falaj were constructed, a series of well-like vertical shafts, connected by gently sloping horizontal tunnels. There are three types of Falaj

  • Daudi (داوودية)with underground aqueducts
  • Ghaili (الغيلية ) requiring a dam to collect the water
  • Aini (العينية ) whose source is a water spring

These enabled large scale agriculture to flourish in a dry land environment

Persia

Main article: Qanat

In Persia from early times [vague] a system of underground aqueducts called Qanat were constructed, a series of well-like vertical shafts, connected by gently sloping tunnels. This technique:

  • taps into subterranean water in a manner that delivers water to the surface without need for pumping. The water drains relying on gravity, with the destination lower than the source, which is typically an upland aquifer.
  • allows water to be transported long distances in hot dry climates without losing a large proportion of the source water to seepage and evaporation.

Roman

Main article: Roman aqueduct

Roman aqueducts were built in all parts of the Roman Empire, from Germany to Africa, and especially in the city of Rome, where they totalled over 415 km. The aqueducts supplied water to large cities across the empire, and set a standard of engineering that was not surpassed for more than a thousand years.

Ancient Indian aqueduct in Hampi

South America

Near the Peruvian town of Nazca, an ancient pre-Columbian system of aqueducts called Puquios were built and are still in use today. They were made of intricately placed stones, a construction material widely used by the Nazca culture. The time period in which they were constructed is still debated, but some evidence supports circa A.D. 540–552, in response to drought periods in the region.[3]

Sri Lanka

Extensive usage of elaborate aqueducts have been found to have been used in Ancient Sri Lanka.

Modern aqueducts

In modern times, the largest aqueducts of all have been built in the United States to supply the country's biggest cities. The Catskill Aqueduct carries water to New York City over a distance of 120 miles (190 km), but is dwarfed by aqueducts in the far west of the country, most notably the Colorado River Aqueduct, which supplies the Los Angeles area with water from the Colorado River nearly 400 km to the east and the 714.5 km California Aqueduct, which runs from the Sacramento-San Joaquin River Delta to Lake Perris. The Central Arizona Project is the largest and most expensive aqueduct constructed in the United States. It stretches 336 miles from its source near Parker, Arizona to the metropolitan areas of Phoenix and Tucson. A modern version of aqueduct is a pipeline bridge.

Uses

Segovia, Spain. Roman aqueduct

Historically, agricultural societies have constructed aqueducts to irrigate crops. Archimedes invented the water screw to raise water for use in irrigation of croplands.

Another use for aqueducts is to supply large cities with drinking water. Some of the Roman aqueducts still supply water to Rome today. In California, United States, three large aqueducts supply water over hundreds of miles to the Los Angeles area. Two are from the Owens River area and a third is from the Colorado River.

In more recent times, aqueducts were used for transportation purposes to allow canal barges to cross ravines or valleys. During the Industrial Revolution of the 18th century, aqueducts were constructed as part of the boom in canal-building.

In modern civil engineering projects, detailed study and analysis of open channel flow is commonly required to support flood control, irrigation systems, and large water supply systems when an aqueduct rather than a pipeline is the preferred solution.

In the past, aqueducts often had channels made of earth or other porous materials but significant amounts of water are lost through such unlined aqueducts. As water gets increasingly scarce, these canals are being lined with concrete, polymers or impermeable soil. In some cases, a new aqueduct is built alongside the old one because it cannot be shut down during construction.

Notable aqueducts

Ancient Greek aqueducts

Roman aqueducts

See also: List of aqueducts in the Roman Empire
Aqueduct of Segovia

Other aqueducts

An Aqueduct in Vila do Conde, Portugal
The Aqueduto dos Pegoes in Tomar, Portugal

See also

Notes

  1. ^ "aqueduct", Britannica CD 2000
  2. ^ A forgotten empire (Vijayanagar): a ... – Google Books
  3. ^ http://www-unix.oit.umass.edu/~proulx/online_pubs/Zurich_Puquios_revised_small.pdf
  4. ^ Mexico – Travel

References

Wikimedia Commons has media related to Aqueduct.

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