Roman aqueduct
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The ancient Romans constructed numerous aqueducts (Latin aquaeductūs, sing. aquaeductus) to supply water to cities and industrial sites. These aqueducts were among the greatest engineering feats of the ancient world, and set a standard not equaled for over a thousand years after the fall of Rome. Many cities still maintain and use the ancient aqueducts for their water supply even today.
The Romans typically built aqueducts to serve any large city in their empire. The city of Rome itself, being the largest city, had the largest concentration of aqueducts, with water being supplied by eleven aqueducts constructed over a period of 500 years.
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[edit] Engineering
The combined length of the aqueducts in the city of Rome was nearly 260 miles (420 km). (Hodge estimates the length at a little over 500 km). However, only 29 miles (47 km) were above ground, as most Roman aqueducts ran beneath the surface of the ground. Building underground helped to keep the water free from disease (the carcasses of animals would not be able to get into the aqueduct) and helped protect the aqueducts from enemy attack. The longest Roman aqueduct, the Zaghouan Aqueduct, is 57.5 miles (92.5 km) in length. It was built in the 2nd century to supply Carthage (in modern Tunisia).
The arcades, a series of arches, popularly shown to depict an aqueduct, should not be confused with the aqueduct itself. These arches, sometimes on several tiers, were constructed to carry the aqueducts over unavoidable dips, such as river valleys.
Roman aqueducts were extremely sophisticated constructions. They were built to remarkably fine tolerances, and of a technological standard that had a gradient of only 34 cm per km (3.4:10,000), descending only 17 m vertically in its entire length of 31 miles (50 km). Powered entirely by gravity, they transported very large amounts of water very efficiently (the Pont du Gard carried 20,000 cubic meters {nearly 6 million gallons} a day and the combined aqueducts of the city of Rome supplied around 1 million cubic meters (300 million gallons) a day (an accomplishment not equalled until the late 19th century and represents a value 25% larger than the present water supply of the city of Bangalore, with a population of 6 million). Sometimes, where depressions deeper than 50 m had to be crossed, gravity pressurized 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.
In addition to the expertise needed to build them, Roman aqueducts required a comprehensive system of regular maintenance to repair accidental breaches, to clear the lines of debris, and to remove buildup of chemicals such as calcium carbonate that naturally occur in the water.
[edit] Construction
Many tools were used in the construction of Roman aqueducts, one example being the chorobates. The chorobates was used to level terrain before construction. It was a wooden object supported by four legs with a flat board on top in which was engraved a half circle. When used the half circle was filled with water and the angle at which there was no water was measured. Another tool used in the construction of the aqueduct was the groma. Gromas were used to measure right angles. A groma consisted of stones hanging off four sticks perpendicular to one another. Distant objects could be marked out against the station of the stones in a horizontal plane.
[edit] Decline of the aqueducts
With the fall of the Roman Empire, although some of the aqueducts were deliberately cut by enemies, many more fell into disuse from the lack of an organized maintenance system. The lack of functioning aqueducts to deliver water had a large practical impact in reducing the population of the city of Rome from its high of over 1 million in ancient times to considerably less in the medieval era.
[edit] Lists of Roman aqueducts
- List of aqueducts in the city of Rome
- List of aqueducts in the Roman Empire
- List of Roman aqueducts by date
[edit] See also
[edit] External links
- Sextus Julius Frontinus, De Aquaeductu Urbis Romae (On the water management of the city of Rome), Translated by R. H. Rodgers, 2003, University of Vermont
- Waters of the City of Rome -- provides sophisticated maps and images
- Imperial Rome Water Systems
- Roman Aqueducts Today
- Lacus Curtius entry on Roman waterworks
- 600 roman aqueducts with 25 descriptions in detail
- (Italian) Map of Roman aqueducts
- NOVA Online: Roman Aqueduct Manual
[edit] References
- Coarelli, Filippo, Guida Archeologica di Roma, Arnoldo Mondadori Editore, Milano, 1989.
- Claridge, Amanda, Rome: An Oxford Archaeological Guide, Oxford University Press, New York, 1998.
- Hodge, A.T., Roman Aqueducts and Water Supply, Gerald Duckworth & Co, London, 2002.
