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aqueduct

aqueduct (ăk´wədŭkt) [Lat.,=conveyor of water], channel or trough built to convey water, chiefly for providing a densely populated region with a supply of freshwater. The flow in aqueducts is ordinarily by means of gravity, although pumps are often used. Some aqueducts consist of tunnels cut through rock, while others are conduits made of some sturdy material. For example, the conduit may consist of steel pipe, concrete, wooden staves, sheet-metal flume, or any of these in combination, the flow being controlled by slide gate and needle valves. Aqueducts enable many cities in the United States to obtain water from a considerable distance. Los Angeles, for example, draws much of its water from the Owens River by means of an aqueduct more than 230 mi (370 km) long. Most of the supply for New York City is conducted through the Catskill Aqueduct and the Croton Aqueduct. The topography of the land influences the design of the aqueduct; usually part of the structure is above ground and part below. Where feasible, an aqueduct may generate hydroelectric power as a byproduct of its operation. Typical of such use is the aqueduct system for Springfield, Mass., which generates power at the foot of Cobble Mt. in addition to supplying the city with water. Aqueducts were employed from early times, probably first in Mesopotamia. Their construction reached a peak of skill in Roman times. Portions of some of the original Roman aqueducts are still standing.

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aqueduct

aqueduct. Structure for artificially conveying a constant supply of water, consisting of a channel (usually covered to prevent evaporation and/or pollution) supported on piers over valleys, roads, etc., and cut through hills. Numerous Antique remains of aqueducts survive, the most impressive being the huge arcaded structure over the Roman Campagna, and that over the River Gard in France. Some C19 aqueducts carrying canals, such as Telford's Pont-y-Cysyllte (1795–1805) over the River Dee, in the Vale of Llangollen, Denbighshire, Clwyd, Wales, consist of cast-iron structures carried on massive piers.

Bibliography

Skempton et al. (eds.) (2002);
Ward-Perkins (1981)

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aqueduct

aqueduct Artificial channel for conducting water from its source to its distribution point. While the ancient Romans were not the first to build these conduits, their aqueducts are the most famous because of their graceful architectural structures. One of their most extensive water systems, which served Rome itself, consisted of 11 aqueducts and took 500 years to complete. California has the world's largest conduit system: it carries water across a distance of more than 800km (500mi).

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aqueduct

aq·ue·duct / ˈäkwəˌdəkt; ˈak-/ • n. an artificial channel for conveying water, typically in the form of a bridge supported by tall columns across a valley. ∎  Anat. a small canal containing fluid. ORIGIN: mid 16th cent.: from obsolete French (now aqueduc), from Latin aquae ductus ‘conduit,’ from aqua ‘water’ + ducere ‘to lead.’

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aqueduct

aqueduct (ak-wi-dukt) n. (in anatomy) a canal containing fluid. a. of the midbrain (cerebral a., a. of Sylvius) a canal connecting the third and fourth ventricles.[ F. Sylvius de la Boe (1614–72), French anatomist]

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aqueduct

aqueduct XVI. — L. aquæductus, i.e. aquæ, g. of aqua water, ductus conveyance (see DUCT). cf. F. aqueduc, †aqueduct (XVI), perh. the immed. source.

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aqueduct

aqueductaddict, afflict, conflict, constrict, contradict, convict, delict, depict, evict, hand-picked, inflict, interdict, Pict, predict, strict •edict •Benedict • verdict •imperfect, perfect, pluperfect, word-perfect •object • subject • relict • district •concoct, decoct •landlocked • dreadlocked •unprovoked, unsmoked •uncooked, unlooked •abduct, adduct, conduct, construct, destruct, duct, instruct, misconduct, obstruct •ventiduct • aqueduct • product •safe-conduct • viaduct •handworked, unworked •mulct • unthanked • sacrosanct •distinct, extinct, succinct •precinct • instinct •conjunct, defunct, disjunct, injunct •adjunct • unasked

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Aqueduct

Aqueduct

History

Technology

Resources

Aqueducts are structures used to carry water from a supply source to distant areas in need of water. The word aqueduct comes from two Latin words, aqua (water) and ducere (to lead). The first aqueducts were built as early as the tenth century BC. While primitive people lived very close to water, as people moved inland and away from direct water supplies, they created systems of water retrieval. Wells were dug to reach underground water supplies. Also, cisterns and underground collecting tanks were used to store water. Eventually, dams were constructed to block water flow, allowing water pressure to increase, and run-off channels were constructed to guide water to specific regions. Early aqueducts redirected water by use of conduits (covered canals, or pipes, usually made of stone) that were often buried a few inches below ground for protection. Aqueducts were driven by the force of gravity pulling water downhill and extended for many miles. The use of aqueducts for drinking water, agriculture, and other uses is a part of Greek, Mexican, Roman, and Asian history. The city of ancient Rome had 11 active aqueducts traversing roughly 300 mi (485 km). Modern aqueducts use electrical power to elevate water that travels through many miles of pipes. Many modern pipes are deep beneath the ground and supply cities with water for personal and industrial use.

History

The first record of an aqueduct appeared in 691 BC in Assyria. This 34 mi (55 km) long aqueduct was simple, consisting of a single arch over one valley. At that time, Greeks were using wells to retrieve water from underground pools. Certain plants, such as fig trees, marked water sources because their roots grow in water. The first Greek aqueduct dates from 530 BC on the island of Samos. This aqueduct was built by an engineer named Eupalinus, who was told to supply the city with water by tunneling a pathway through a mountain. The Samos aqueduct extended for about 1 mi (1.6 km) underground and had a diameter of 8 ft (2.4 m). These first aqueducts demonstrated an understanding of siphons and other basic hydraulic principles.

Ancient Roman aqueducts evolved into an extensive network of canals supplying the city with water. Romes first aqueduct, the Aqua Appia, was built in 312 BC and was a simple subterranean covered ditch. Roman aqueducts were usually built as open troughs covered with a top and then with soil. They were made

from a variety of materials, including masonry, lead, terra cotta, and wood. The Appia was about 50 ft (15 m) underground to make it inaccessible to Roman enemies on the citys outskirts. The Anio Vetus, built in 272 BC, brought more water to the city. Both the Appia and the Vetus had sewer-like designs.

Later Roman aqueducts were mainly built to meet the needs of the people or the desires of the rulers of the time. The average Roman aqueduct was 1050 mi (1680 km) long with a 715 sq ft (0.71.4 sq m) cross-section. Aqueducts were generally wide enough for a man to enter and clean. The Aqua Marcia, built in 140 BC, was made of stone and had lofty arches. The Aqua Tepula of 125 BC was made from poured concrete.

Advances in irrigation and water management are also found South America. In the Mexican Tehuacan Valley, evidence of irrigation dates back to around 700 BC in the remains of the Purron Dam. The dam was used to direct water to domestic and crop regions for several hundred years. In the same valley, the Xiquila Aqueduct was built around AD 400.

More recently, North American aqueducts include the Potomac aqueduct in Washington, DC. This aqueduct, which was built in 1830, extends over the Potomac River at the Key Bridge, which joins Northern Virginia and the Georgetown area of the city. It was built with support from eight piers and two stone abutments to carry water from the upper Potomac to the city.

Later aqueducts of the United States include the Colorado River Aqueduct, which supplies Los Angeles, and the Delaware River Aqueduct, which carries water into New York. In addition, aqueducts carry water from northern to southern California. The southwestern region of the United States is particularly dry and

KEY TERMS

Aquifer A formation of soil or rock that holds water underground.

Conduit A structure such as a pipe or channel for transporting fluid.

requires water import. Water can be collected from aquifers (underground water reservoir), rivers, lakes, or man-made reservoirs.

Technology

While modern water pipes are much wider (2030 ft or 6.19.1 m in diameter) and significantly longer (hundreds of miles long) than the first aqueducts, the hydraulic principles governing water carriage remain essentially the same. Water flows along gradients, and its velocity depends on a number of factors. Water flows more quickly along steeper gradients, but wear and tear on such pipes is greater, resulting in the need for more frequent repair. More gradual sloping pipes result in slower-flowing water with greater sludge deposits; hence, these pipes require more cleaning with less repair.

Water velocity along conduits is also greater in larger, smoother pipes. Pipes or canals that have rough surfaces disrupt water flow, slowing it down. In addition, larger diameter passageways provide less resistance, because a smaller percentage of the flowing water is retarded by the surface friction of the conduit.

The use of water to generate other forms of power is not new at all. Both the ancient Greeks and Romans used water mills for work in such places as flour factories. In such mills, aqueducts were used to supply water on a relatively continuous basis. A modern application of water power is hydroelectric power.

Resources

BOOKS

Hodge, A. Roman Aqueducts and Water Supply. London: Gerald Duckworth & Co., 2002.

Hodge, A., editor. Future Currents in Aqueduct Studies. Leeds: Francis Cairns Ltd., 1991.

Reisner, Marc. Cadillac Desert: The American West and its Disappearing Water. New York: Penguin Books Ltd., 1993.

Louise Dickerson

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Aqueduct

Aqueduct

Aqueducts are structures used to carry water from a supply source to distant areas in need of water. The word aqueduct comes from two Latin words, aqua (water) and ducere (to lead). The first aqueducts were built as early as the tenth century b.c. by ancient communities. While primitive people lived very close to water, as people moved inland and away from direct water supplies, they created systems of water retrieval. Wells were dug to reach underground water supplies. Also, cisterns, underground collecting tanks, were used to store water. Eventually, dams were constructed to block water flow, allowing water pressure to increase, and run-off channels were constructed to guide water to specific regions. Early aqueducts redirected water by use of conduits (covered canals, or pipes, usually made of stone) that were often buried a few inches below ground for protection. Aqueducts were driven by the force of gravity pulling water downhill and extended for many miles. The use of aqueducts for drinking water, agriculture, and other uses is a part of Greek, Mexican, Roman, and Asian history. The city of ancient Rome had 11 active aqueducts traversing roughly 300 mi (485 km). Modern aqueducts use electrical power to elevate water that travels through many miles of pipes. Many modern pipes are deep beneath the ground and supply cities with water for personal and industrial use.


History

The first record of an aqueduct appeared in 691 b.c. in Assyria. This 34 mi (55 km) long aqueduct was simple, consisting of a single arch over one valley. At that time, Greeks were using wells to retrieve water from underground pools. Certain plants, such as fig trees, marked water sources because their roots grow in water. The first Greek aqueduct followed in 530 b.c. on the island of Samos. This aqueduct was built by an engineer named Eupalinus, who was told to supply the city with water by tunneling a pathway through a mountain. The Samos aqueduct extended for about 1 mi (1.6 km) underground, and had a diameter of 8 ft (2.4 m). These first aqueducts demonstrated an understanding of siphons and other basic hydraulic principles.

While ancient Roman aqueducts evolved into an extensive network of canals supplying the city, the first one, the Aqua Appia, was not built until 312 b.c. This aqueduct was a simple subterranean covered ditch. Roman aqueducts were usually built as open troughs, covered with a top, and then covered with soil . They were made from a variety of materials including masonry, lead, terra cotta, and wood . The Appia was about 50 ft (15 m) underground to make it inaccessible to Roman enemies on the city's outskirts. The Anio Vetus, built in 272 b.c., brought more water to the city, but both the Appia and the Vetus had sewer-like designs. The Aqua Marcia, built in 140 b.c., was made of stone and had lofty arches. The Aqua Tepula of 125 b.c. was made from poured concrete . Later Roman aqueducts were mainly built to meet the needs of the people or the desires of the rulers of the time. The average Roman aqueduct was 10–50 mi (16–80 km) long with a 7–15 sq ft (0.7–1.4 sq m) cross-section. Aqueducts were generally wide enough for a man to enter and clean.

Around the world, communities made advances in irrigation and water management. In the Mexican Tehuacan Valley, evidence of irrigation dates back to around 700 b.c. in the remains of the Purron Dam. The dam was used to direct water to domestic and crop regions for several hundred years. In the same valley, the Xiquila Aqueduct was built around a.d. 400. Early North American aqueducts include the Potomac aqueduct in Washington, DC. This aqueduct, which was built in 1830, extends over the Potomac River at the Key Bridge, which joins Northern Virginia and the Georgetown area of the city. It was built with support from eight piers and two stone abutments to carry water from the upper Potomac to the city.

Later aqueducts of the United States include the Colorado River Aqueduct that supplies Los Angeles and the Delaware River Aqueduct that carries water into New York. In addition, aqueducts carry water from northern to southern California. The southwestern region of the United States is particularly dry and requires water import. Water can be collected from aquifers (underground water reservoir), rivers , lakes, or man-made reservoirs.


Technology

While modern water pipes are much wider (20–30 ft or 6.1–9.1 m in diameter) and significantly longer (hundreds of miles long) than the first aqueducts, the hydraulic principles governing water carriage remain essentially the same. Water flows along gradients, and its velocity depends on a number of factors. Water flows more quickly along steeper gradients, but wear and tear on such pipes is greater, resulting in the need for more frequent repair. More gradual sloping pipes result in slower-flowing water with greater sludge deposits; hence, these pipes require more cleaning with less repair.

Water velocity along conduits is also greater in larger, smoother pipes. Pipes or canals that have rough surfaces disrupt water flow, slowing it down. In addition, larger diameter passageways provide less resistance, because a smaller percentage of the flowing water is retarded by the surface friction of the conduit. Thus, smaller diameter pipes slow the flow of water compared to larger diameter pipes.

The use of water to generate other forms of power is not new at all. The ancient Greeks and Romans both used water mills for work in such places as flour factories. In such mills, aqueducts were used to supply water on a relatively continuous basis. A modern application of water power is hydroelectric power.


Resources

books

Hodge, A. Roman Aqueducts and Water Supply. London: Gerald Duckworth & Co., 1992.

Hodge, A., ed. Future Currents in Aqueduct Studies. Leeds: Francis Cairns Ltd., 1991.

Reisner, Marc. Cadillac Desert: The American West and its Disappearing Water. New York: Penguin Books Ltd., 1993.


Louise Dickerson

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aquifer

—A formation of soil or rock that holds water underground.

Conduit

—A structure such as a pipe or channel for transporting fluid.

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