Aqueduct
An
aqueduct is an artificial (man-made) channel that is constructed to convey water from one location to another. The word is derived from the
Latin aqua, "water," and
ducere, "to lead." Many aqueducts are raised above the landscape, resembling
bridges rather than
rivers. Sufficiently large aqueducts (
water bridges) may also be usable by
ships. They are similar to
viaducts, but carry water instead of a road or railway. While a road bridge often carries the roadway at a more elevated level than the rest of the road, such a variation of height is not possible for an aqueduct.
Although famously associated with the
Ancient 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).
In the new world, the
Aztec capital of
Tenochtitlán was watered by two aqueducts in the middle of the
second millennium.
Roman aqueducts
Roman aqueducts were built all over the
Roman Empire, from Germany to Africa, and especially in the city of Rome itself, where they totalled over 260 miles (416 km). The aqueducts were important for supplying large cities across the empire, and they set a high standard of engineering that was not surpassed for more than a thousand years.
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
High Middle Ages. An example of an extant small scale aqueduct system built in 1202 by
Cistercian monks is the Spanish
Real Monasterio de Nuestra Senora de Rueda, whose central heating and waste disposal system relied upon a series of aqueducts originating from a diversion of the
Ebro River. Through most of the
Middle Ages and even up to 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.
|
Remains of the Schoharie Crossing, an aqueduct that once carried the Erie Canal over the Schoharie Creek near Amsterdam, New York. |
In modern times the largest aqueducts (also know like
transvasements) 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.
Historically, many agricultural societies have constructed aqueducts to
irrigate crops.
Archimedes invented the
water screw to raise water for use in irrigation of croplands.
Another widespread use for aqueducts is to supply large cities with clean drinking water. Some of the famed Roman aqueducts still supply water to
Rome today. In
California,
USA, 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, many aqueducts were constructed as part of the general 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. The aqueduct is a simple way to get water to other ends of a field.
In the past, aqueducts often had channels made of dirt or other porous materials. 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.
Navigable aqueducts
*aqueduct near
Roelofarendsveen,
Netherlands: carries the
Ringvaart canal over the A4
highway and the
HSL Zuid being constructed, which are situated on land below the level of the canal (and below sea level)
*Gouwe aqueduct, near
Gouda,
Netherlands: carries the
Gouwe river over the A12 highway, which is on land below the level of the river
*
Benjamin Outram's 44ft-long single-span Holmes Aqueduct on the
Derby Canal in
Derby was the world's first navigable
cast iron aqueduct, narrowly predating
Thomas Telford's 186ft-long
Longdon-on-Tern Aqueduct on the
Shrewsbury Canal, sometimes described as the world's first
large-scale navigable cast iron aqueduct.
*the
Pontcysyllte Aqueduct carries the
Llangollen Canal over the River Dee in north
Wales, and was designed by
Thomas Telford and opened in
1805.
*the
Union Canal in
Scotland has many aqueducts, including the
Slateford Aqueduct that takes the canal over the
Water of Leith, the
Almond Aqueduct over the River Almond at
Ratho and the very impressive
Avon Aqueduct over the River Avon. This is the second longest aqueduct in the
United Kingdom.
*in recent years the building of the
Lichfield Aqueduct prompted the UK government to pass legislation preventing a road being built in the path of a canal being renovated without providing a tunnel or aqueduct for it to pass.
*The
Bridgewater Canal is carried across the lower
Manchester Ship Canal by the
Barton Swing Aqueduct - a form of
swing bridge. A 234ft section of the aqueduct rotates through 90 degrees to allow vessels to pass along the Ship Canal.
*The
Magdeburg Water Bridge in
Germany connects the
Elbe-Havel canal to the important
Mittellandkanal. Nearly 1 km long, it is the longest Water Bridge in Europe.
Ancient Greek aqueducts
*The
Eupalinian aqueduct on the
Greek island of
Samos. An ancient subterranean aqueduct.
Roman aqueducts
*The
Pont du Gard in southern
France*
Barbegal aqueduct, France
*
Eifel aqueduct,
Germany*
Caesarea Palaestina,
Israel*
Segovia,
Spain*
Mérida, Spain
*
Tarragona, Spain
*
Almuñécar, Spain (5 aqueducts - 4 still in use)
*
Valens aqueduct,
Istanbul,
Turkey*
Aqua Augusta, Italy
Other aqueducts
*
Aqueduct of Teruel, Spain
*
Central Arizona Project Aqueduct*
Chirk Aqueduct,
Wales - built between
1796 and
1801*
Pontcysyllte Aqueduct, Wales - built between
1795 and
1805*
Roquefavour aqueduct, France - built between
1842 and
1847*
Aqueduct St-Clément,
Montpellier, France - 17th century
*
Winnipeg Aqueduct,
Manitoba, Canada - built between
1913 and
1919*
Päijänne-tunneli is 120 kilometers long underground aqueduct (continuous tunnel) connecting lake
Päijänne to
Greater Helsinki.
*
Wan Mat Saman Aqueduct,
Kedah,
Malaysia - built between
1900 and
1909*Aqueduct of
Querétaro,
Mexico - built between
1726 and
1738, 1.3 km long and featuring 74 arches.
*
Levadas, 1350 miles of 17th century aqueducts on the
Portuguese island of
Madeira.
*
Aqueduct (Roman)*
Irrigation*
Leat*
Pipeline - some used to carry water
*
Roman architecture*
Sanitation in Ancient Rome*
Transvasement*
Viaduct - a similar structure to carry a roadway
*
Water bridge - a similar structure to carry barges
*
Water resources*
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
*
Aqueduct entry from
Encyclopædia Britannica Eleventh Edition*
Website about aqueducts*
Imperial Rome Water Systems*
Roman Aqueducts Today*
600 Roman aqueducts with 25 descriptions in detail*
Lacus Curtius entry on Roman waterworks
