Aqueduct

:This article is about the structure aqueduct, for the racecourse see Aqueduct Racetrack.

History

Although most famously associated with the Romans, aqueducts were devised centuries earlier in the Middle East, where peoples such as the Babylonians and Egyptians built sophisticated irrigation systems. Roman-style aqueducts were used as early as the 7th century BC, when the Assyrians built a limestone aqueduct 30 feet (10 m) high and 900 feet (300 m) long to carry water across a valley to their capital city, Nineveh; the full length of the aqueduct ran for 50 miles (80 km).

Related Topics:
Romans - Middle East - Babylonians - Egyptians - 7th century BC - Assyrians - Nineveh

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The Romans constructed numerous aqueducts to supply water to cities and industrial sites. The city of Rome itself had the largest concentration of aqueducts, with water being supplied by eleven aqueducts constructed over a period of 500 years, with a combined length of nearly 260 miles (350 km). Only 29 miles (47 km) of these were above ground, however; most Roman aqueducts were constructed underground (the Eifel Aqueduct in Germany provides a very well-preserved example). This helped to keep the water free from disease (the carcasses of animals would not be able to get into the aqueduct) and helped protect them from enemy attack. The longest Roman aqueduct was the one built in the 2nd century AD to supply Carthage in what is now Tunisia, which ran for 87 miles (141 km).

Related Topics:
Rome - Eifel Aqueduct - Germany - 2nd century - Carthage - Tunisia

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Roman aqueducts were extremely sophisticated constructions, of a technological standard which was not to be equaled for over 1000 years after the fall of the Roman Empire. They were built to remarkably fine tolerances: the aqueduct of which Pont du Gard in Provence was a part had a gradient of only 34 cm per km (1:3,000), descending only 17 m vertically in its entire length of 31 miles (50 km). They were powered entirely by gravity, transporting very large amounts of water very efficiently (the Pont du Gard carried 20,000 cubic meters {44 million gallons} a day). Sometimes, where depressions deeper than 50 m had to be crossed, gravity pressurised pipelines called inverted siphons were used to force water uphill (although they almost always used venter bridges as well). Modern hydraulic engineers use similar techniques to enable sewers and water pipes to cross depressions.

Related Topics:
Pont du Gard - Provence - Gravity - Inverted siphon - Hydraulic engineers - Sewer

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Much of the expertise of the Roman engineers was lost in the Dark Ages and in Europe the construction of aqueducts largely ceased until the 19th century. Water was instead usually supplied through the digging of wells, though this could cause serious public health problems when local water supplies became contaminated. One notable exception was the New River, a man-made waterway in England, opened in 1613 to supply London with fresh drinking water over a distance of 38 miles (62 km). The development of canals provided another spur to aqueduct building. However, it was not until the 19th century that aqueduct building resumed on a large scale to supply fast-growing cities and water-hungry industries. The developments of new materials (such as cast iron) and new technologies (such as steam power) enabled significant improvements to be made. For instance, cast iron permitted the construction of larger, more highly pressurised inverted siphons, while steam- and electrically-powered pumps enabled a major increase in the quantity and speed of water flow. England led the world in aqueduct construction, with notable examples being built to convey water to Birmingham, Liverpool and Manchester.

Related Topics:
Dark Ages - 19th century - Well - New River - England - 1613 - London - Canal - Cast iron - Steam power - Birmingham - Liverpool - Manchester

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The largest aqueducts of all have been built in the United States to supply that country's biggest cities. The Catskill Aqueduct carries water to New York over a distance of 120 miles (190 km), but it 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 250 miles (400 km) to the east. Although such aqueducts are undoubtedly great engineering achievements, the huge quantity of water that they transport has led to serious environmental damage resulting from the depletion of rivers.

Related Topics:
United States - Catskill Aqueduct - New York - Colorado River Aqueduct - Los Angeles - Colorado River

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