Aqueduct (water supply)

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The Central Arizona Project allows passage of water from the Colorado River to central and southern Arizona. Arizona cap canal.jpg
The Central Arizona Project allows passage of water from the Colorado River to central and southern Arizona.

An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. [1] The term aqueduct also often refers specifically to a bridge carrying an artificial watercourse. [1] Aqueducts were used in ancient Greece, ancient Egypt, and ancient Rome. In modern times, the largest aqueducts of all have been built in the United States to supply large cities. The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.



The word is derived from the Latin aqua (water) and ductus (led, guided).

Ancient aqueducts

Although particularly associated with the Romans, aqueducts were devised much earlier in Greece, the Near East, Nile Valley, 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, which included a 10 m high section to cross a 300 m wide valley, to carry water to their capital city, Nineveh. [2]


Ancient Indian aqueduct in Hampi Hampi aqueduct.JPG
Ancient Indian aqueduct in Hampi

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. [3] The waterways supplied water to royal bath tubs.


In Oman from the Iron Age, in Salut, Bat, and other sites, a system of underground aqueducts called falaj or qanāts were constructed, a series of well-like vertical shafts, connected by gently sloping horizontal tunnels.

There are three types of falaj:

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


Scheme of a qanat, an underground form of aqueduct popular in ancient Persia Qanat-3.svg
Scheme of a qanat, an underground form of aqueduct popular in ancient Persia

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

Petra, Jordan

Nabataean aqueduct in Petra, Jordan PetraAqueduct.jpg
Nabataean aqueduct in Petra, Jordan

Throughout Petra, Jordan, the Nabataean engineers took advantage of every natural spring and every winter downpour to channel water where it was needed. They constructed aqueducts and piping systems that allowed water to flow across mountains, through gorges and into the temples, homes, and gardens of Petra's citizens. Walking through the Siq, one can easily spot the remains of channels that directed water to the city center, as well as durable retention dams that kept powerful flood waters at bay.


On the island of Samos, the Tunnel of Eupalinos was built during the reign of Polycrates (538-522 BC). It is considered an underground aqueduct and brought fresh water to Pythagoreion for roughly a thousand years.


The multiple arches of the Pont du Gard, in Roman Gaul. Its lower tiers carry a road across the river, and the upper tiers support an aqueduct conduit that carried water to Nimes Pont du Gard BLS.jpg
The multiple arches of the Pont du Gard, in Roman Gaul. Its lower tiers carry a road across the river, and the upper tiers support an aqueduct conduit that carried water to Nimes

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 kilometres (258 mi). The aqueducts supplied fresh water to public baths and for drinking water, in large cities across the empire, and set a standard of engineering that was not surpassed for more than a thousand years. Bridges, built in stone with multiple arches, were a distinctive feature of Roman aqueducts and hence the term aqueduct is often applied specifically to a bridge for carrying water. [1]

South America

Underground aqueducts of Cantalloc, Nazca, Peru Acueductos subterraneos de Cantalloc, Nazca, Peru, 2015-07-29, DD 01.JPG
Underground aqueducts of Cantalloc, Nazca, Peru

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. [4]

The Guayabo National Monument of Costa Rica, a park covering the largest archaeological site in the country, contains a system of aqueducts. The complex network of uncovered and covered aqueducts still functions well. [5] The aqueducts are constructed from rounded river stones, which are mostly made of volcanic rock. [6] The civilization that constructed the aqueduct system remains a mystery to archaeologists; it is suspected that Guayabo's aqueducts sat at a point of ancient cultural confluence between Aztecs, Mayans, and Incas.

North America

When Europeans saw the Aztec capital Tenochtitlán, early in the 16th century, the city was watered by two aqueducts. One of these, Chapultepec Aqueduct, built circa 1420, was rebuilt by the Spanish almost three hundred years later. Originally tracing part of its path over now-gone Lake Texcoco, only a fragment remains in Mexico City today.

Sri Lanka

Extensive usage of elaborate aqueducts have been found to have been used in ancient Sri Lanka. The best example is the Yoda Ela or Jaya Ganga, an 87 kilometres (54 mi) long water canal carrying excess water between two artificial reservoirs with a gradient of 10 to 20 cm per kilometer during the fifth century AD. However, the ancient engineering methods in calculating the exact elevation between the two reservoirs and the exact gradient of the canal to such fine precision had been lost with the fall of the civilization in 13th Century. [7]

Modern aqueducts

Modern aqueducts are a central part of many countries' water distribution infrastructure.

The United States' aqueducts are some of the world's largest. 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 242-mile (389-km) Colorado River Aqueduct, which supplies the Los Angeles area with water from the Colorado River nearly 250 miles to the east and the 701.5-mile (1,129.0 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.

An aqueduct in New Zealand, "the Oamaru Borough Race", was constructed in the late 19th century to deliver water (and water-power) about 50 km from the Waitaki River at Kurow to the coastal town of Oamaru.

In Spain, the Tagus-Segura Water Transfer system of aqueducts opened in 1979 and transports water 286 kilometres (178 mi) from north to south. [8]

In China, the South–North Water Transfer Project aims to connect the Yangtze River basin to Beijing through three separate systems. The project will reuse part of the Grand Canal of China.


Open channels

The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts, for instance the Central Arizona Project uses 7.3 m (24 ft) wide channels. [9] A major factor in the design of all open channels is its gradient. A higher gradient allows a smaller channel to carry the same amount of water as a larger channel with a lower gradient, but increases the potential of the water to damage the aqueduct's structure. A typical Roman aqueduct had a gradient of about 1:4800. [10]

Artificial rills

Artificial rills, known locally as Bachle, run along some old-town streets in the city of Freiburg, Germany. Freiburg Baechle Rills.jpg
Artificial rills, known locally as Bächle, run along some old-town streets in the city of Freiburg, Germany.
An artificial rill, part of the Falaj water transportation system, at Al Ain Oasis, in the Abu Dhabi Emirate. Falaj at al ain.jpg
An artificial rill, part of the Falaj water transportation system, at Al Ain Oasis, in the Abu Dhabi Emirate.

A constructed functional rill is a small canal or aqueduct of stone, brick, concrete, or other lining material, usually rectilinear in cross section, for water transportation from a source such as a river, spring, reservoir, qanat, or aqueduct for domestic consumption or agricultural irrigation of crop land uses.

Rills were traditionally used in Middle Eastern and Mediterranean climate cultures of ancient and historical eras; and other climates and continents worldwide. They are distinguished from a 'water ditch' by being lined to reduce absorption losses and to increase durability. The Falaj irrigation system at the Al Ain Oasis, in present-day Abu Dhabi Emirate, uses rills as part of its qanat water system. Sometimes in the Spanish language they are called Acequias .

Rills are also used for aesthetic purposes in landscape design. Rills are used as narrow channels of water inset into the pavement of a garden, as linear water features, and often tiled and part of a fountain design.

The historical origins are from paradise garden religious images that first translated into ancient Persian Gardens. Rills were later exceptionally developed in the Moorish (Spanish) Gardens of Al-andalus, such as at the Alhambra in Granada; and also in other Islamic gardens, cultures, and countries. Early 20th century examples are in the María Luisa Park gardens in Seville, Spain; and at the Casa del Herrero gardens in Montecito, California.


Aqueducts sometimes run for some or all of their path through tunnels constructed underground. A version of this common in North Africa and Central Asia that has vertical wells at regular intervals is called a qanat. One historic example found in Syria, the Qanat Firaun, extends over 100 kilometers. [11]


The Los Angeles Aqueduct LA Aqueduct Antelope Valley.jpg
The Los Angeles Aqueduct

Modern aqueducts may also make extensive use of pipelines. Pipelines are useful for transporting water over long distances when it needs to move over hills, or where open channels are poor choices due to considerations of evaporation, freezing, pollution, or environmental impact. They can also be used to carry treated water.


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. It also help drought-prone areas with water supply. 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 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

Other aqueducts

See also


  1. 1 2 3 "Aqueduct". Britannica (CD ed.). 2000.
  2. Jacobsen, Thorkild; Lloyd, Seton (1935), Sennacherib's Aqueduct at Jerwan (PDF), University of Chicago Press, Oriental Institute Publication 24
  3. Sewell, Robert (1900). A Forgotten Empire (Vijayanagar): A Contribution to the History of India (Google Books). ISBN   9788120601253.
  4. Zurich Puquios revised (PDF), U Mass
  5. Blake, Beatrice (2009). The New Key to Costa Rica. Ulysses Press. p. 197. ISBN   9781569756966.
  6. Alvarado, Guillermo E.; Soto, Gerardo J. (1 October 2008). "Volcanoes in the pre-Columbian life, legend, and archaeology of Costa Rica (Central America)". Journal of Volcanology and Geothermal Research. 176 (3): 356–362. Bibcode:2008JVGR..176..356A. doi:10.1016/j.jvolgeores.2008.01.032.
  8. Claver, José Manuel (27 October 2015). "El río que nos une" (Opinion). El Pais. Retrieved 8 February 2016.
  9. "Request Rejected".
  10. Mays, L. (Editor), Ancient Water Technologies, Springer, 2010. p. 119
  11. Schulz, Matthias (11 March 2009). "Rome's Tremendous Tunnel: The Ancient World's Longest Underground Aqueduct". Spiegel Online.
  12. Mexico – Travel

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Qanat Water management system using underground channels

A qanat or kariz, is a system for transporting water from an aquifer or water well to the surface, through an underground aqueduct. Constructed in Iran, Iraq and numerous other societies, this is an ancient system of water supply which allows water to be transported over long distances in hot dry climates without loss of much of the water to evaporation. The system has the advantage of being resistant to natural disasters such as earthquakes and floods, and to deliberate destruction in war. Furthermore, it is almost insensitive to the levels of precipitation, delivering a flow with only gradual variations from wet to dry years.

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Delaware Aqueduct

The Delaware Aqueduct is an aqueduct in the New York City water supply system. It takes water from the Rondout, Cannonsville, Neversink, and Pepacton reservoirs on the west bank of the Hudson River through the Chelsea Pump Station, then into the West Branch, Kensico, and Hillview reservoirs on the east bank, ending in at Hillview in Yonkers, New York.

High Bridge (New York City) Bridge between Manhattan and the Bronx, New York

The High Bridge is the oldest bridge in New York City, having originally opened as part of the Croton Aqueduct in 1848 and reopened as a pedestrian walkway in 2015 after being closed for over 45 years. A steel arch bridge with a height of 140 ft (43 m) over the Harlem River, it connects the New York City boroughs of the Bronx and Manhattan. The eastern end is located in the Highbridge section of the Bronx near the western end of West 170th Street, and the western end is located in Highbridge Park in Manhattan, roughly parallel to the end of West 174th Street.

Croton Aqueduct Pipeline that carried water to New York City from its reservoirs in 19th century

The Croton Aqueduct or Old Croton Aqueduct was a large and complex water distribution system constructed for New York City between 1837 and 1842. The great aqueducts, which were among the first in the United States, carried water by gravity 41 miles (66 km) from the Croton River in Westchester County to reservoirs in Manhattan. It was built because local water resources had become polluted and inadequate for the growing population of the city. Although the aqueduct was largely superseded by the New Croton Aqueduct, which was built in 1890, the Old Croton Aqueduct remained in service until 1955.

Navigable aqueduct

Navigable aqueducts are bridge structures that carry navigable waterway canals over other rivers, valleys, railways or roads. They are primarily distinguished by their size, carrying a larger cross-section of water than most water-supply aqueducts. Although Roman aqueducts were sometimes used for transport, aqueducts were not generally used until the 17th century when the problems of summit level canals had been solved and modern canal systems were developed. The 662-metre (2,172 ft) long steel Briare aqueduct carrying the Canal latéral à la Loire over the River Loire was built in 1896. It was ranked as the longest navigable aqueduct in the world for more than a century, until the Magdeburg Water Bridge in Germany took the title in the early 21st century.

Ancient Roman engineering

The ancient Romans were famous for their advanced engineering accomplishments. Technology for bringing running water into cities was developed in the east, but transformed by the Romans into a technology inconceivable in Greece. The architecture used in Rome was strongly influenced by Greek and Etruscan sources.

Aqua Appia

The Aqua Appia was the first Roman aqueduct, constructed in 312 BC by the co-censors Gaius Plautius Venox and Appius Claudius Caecus, the same Roman censor who also built the important Via Appia.

Aqua Virgo

The Aqua Virgo was one of the eleven Roman aqueducts that supplied the city of ancient Rome. It was completed in 19 BC by Marcus Agrippa, during the reign of the emperor Augustus and was built mainly to supply the contemporaneous Baths of Agrippa in the Campus Martius.

Aqua Augusta (Naples) Aqueduct

The Aqua Augusta, or Serino Aqueduct, was one of the largest, most complex and costliest aqueduct systems in the Roman world; it supplied water to at least eight ancient cities in the Bay of Naples including Pompeii and Herculaneum. This aqueduct was unlike any other of its time, being a regional network rather than being focussed on one urban centre.

Roman aqueduct Type of aqueduct built in ancient Rome

The Romans constructed aqueducts throughout their Republic and later Empire, to bring water from outside sources into cities and towns. Aqueduct water supplied public baths, latrines, fountains, and private households; it also supported mining operations, milling, farms, and gardens.

Sanitation in ancient Rome, acquired from the Etruscans, was well advanced compared to other ancient cities and was providing water supply and sanitation services to residents of Rome. Although there were many sewers, public latrines, baths and other sanitation infrastructure, disease was still rampant. The baths are known to symbolise the "great hygiene of Rome". Although the baths may have made the Romans smell good, they were a cesspool of waterborne diseases.

Boyds Corner Reservoir

The Boyds Corner Reservoir is a small reservoir in Putnam County, New York. It is in the town of Kent, New York, and is about 50 miles north of New York City. It is the northernmost reservoir in the Croton River watershed, but is not part of the New York City water supply system's Croton Watershed. and was formed by impounding the middle of the West Branch of the Croton River, submerging the village of Boyds Corner.

Water tunnels are tunnels used to transport water to areas with large populations or agriculture. They are frequently part of aqueducts. Some aqueducts, such as the Delaware Aqueduct are single long tunnels. In other cases, such as the San Jacinto tunnel on the Colorado River Aqueduct, water tunnels form parts of far longer aqueducts. In cases where the outflow of a water tunnel is into an existing stream or river flowing to the point of water use, the term aqueduct is less likely to be used, as with the Harold D. Roberts Tunnel from Dillon Reservoir to the North Fork South Platte River.

Interbasin transfer

Interbasin transfer or transbasin diversion are terms used to describe man-made conveyance schemes which move water from one river basin where it is available, to another basin where water is less available or could be utilized better for human development. The purpose of such designed schemes can be to alleviate water shortages in the receiving basin, to generate electricity, or both. Rarely, as in the case of the Glory River which diverted water from the Tigris to Euphrates River in modern Iraq, interbasin transfers have been undertaken for political purposes. While ancient water supply examples exist, the first modern developments were undertaken in the 19th century in Australia, India and the United States; large cities such as Denver and Los Angeles would not exist as we know them today without these diversion transfers. Since the 20th century many more similar projects have followed in other countries, including Israel, Canada and China. Utilized alternatively, the Green Revolution in India and hydropower development in Canada could not have been accomplished without such man-made transfers.

Pont dAël

The Pont d'Aël is a Roman aqueduct located in a village of the same name in the comune of Aymavilles in Aosta Valley, northern Italy. It was built in the year 3BC for irrigation purposes and supplying water for the newly founded colony of Augusta Praetoria, which is now known as Aosta. The water was directed through a neighbouring valley 66 m above the floor of the Aosta valley, through a sophisticated system. The aqueduct is 6 km long in total. In addition to its unusual position, the construction, which was originally thought to be a three-story structure, shows more unique features such as a control corridor below the water line, as well as explicit private funding. Today, the water channel of the aqueduct serves as a public walking trail.

Gadara Aqueduct Former Roman aqueduct

The Gadara Aqueduct, also called Qanatir Fir'awn or Qanat Fir'aun, was a Roman aqueduct supplying water for some of the cities of the Decapolis. It serviced Adraha, Abila, and Gadara. The aqueduct has the longest known tunnel of the Classical era.

Aqueduct (bridge) Structure constructed to convey water

Aqueducts or water bridges are bridges constructed to convey watercourses across gaps such as valleys or ravines. The term aqueduct may also be used to refer to the entire watercourse, as well as the bridge. 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 end. The word is derived from the Latin aqua ("water") and ducere, therefore meaning "to lead water". A modern version of an aqueduct is a pipeline bridge. They may take the form of tunnels, networks of surface channels and canals, covered clay pipes or monumental bridges.


Further reading