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Aqueduct

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Aqueduct
The word aqueduct derives from the Latin words aqua meaning water and ducere meaning to lead.[1] An aqueduct is therefore best described as an artificially constructed kind of structure such as a channel, trough, or conduit, that is sometimes elevated and used to transport water from a remote location or source to another.[2] An aqueduct can also refer to a bridge-like structure that supports a conduit or canal passing over a river, valley, or low ground similar to a viaduct.[3]

In ancient civilizations, aqueducts were primarily used to transport a pure, useable water supply from a distant location to a mass populated area such as a city, town, or village. The construction of the aqueduct typically followed the natural contour of land and as a result, were built raised above on walls either pierced or arched, or below the ground.[4] Today, the use for an aqueduct remains relatively unchanged.

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[edit] History

The actual concept of an aqueduct is quite old, dating as far back as the 10th century B.C. During primitive times, human survival was dependant on living in close proximity to a viable water supply. As time passed however, people starting migrating further inland and away from water resources. Aqueducts were therefore constructed as a mechanism to carry the water from the source directly to people.[5]

The very first aqueducts were used by many ancient civilizations such as those in Babylon, Assyria, and Egypt. These primitive aqueducts were built rather simply as open canals dug out between a river and city. The force of gravity however propelled the flow of water into the city centers.[6]

The first actual recorded aqueduct was constructed in Assyria in 691 B.C. and was estimated to be 34 miles (55 km) long and featuring a single arch located and spanning over one large, valley.[7]

[edit] Qanats

More advanced aqueduct systems called qanats were developed in Persia. They consisted of tunnels that began in the foothills of mountains and wound their way eventually downhill to transport water to populated areas. The qanats were excavated by hand with vertical shafts placed every 66 to 98 feet (20 to 30 m) along the length of the qanat so material could be removed. The shafts also provided ventilation and an access point for repairs. Excavated material was used to build the sides of each shaft opening up into a mound that prevented water run-off from entering into the qanat. Reinforced rings of burnt clay were also placed inside each qanat to prevent cave-ins. To this day, qanats are still used in Iran and built using the same technique.[8]

[edit] Roman Aqueducts

The most prolific engineers of aqueducts amongst all ancient civilizations were the Romans. Over a period of 500 years the Romans constructed about 11 aqueducts that fueled Rome’s water supply. The first aqueduct in Rome was built in 312 B.C. and the last in 226 A.D. By the time the last aqueduct was built in the city, Rome was being supplied 50 million gallons (189 million L) of water daily via 359 miles (578 km) of aqueducts. The average Roman aqueduct was 10 to 50 miles (16 to 80 km) long with a seven- to 15-square foot (0.7- to 1.4-m2) cross-section, making it big enough to enter into and clean.[9] The Romans also employed the use of aqueducts throughout their empire in countries such as Spain, France, and Northern Africa, with some of these structures still standing and being used even to this day.[10]

Again, Roman aqueducts relied on the flow of gravity to carry the water through conduits that were built underground, at ground level and elevated. Aqueducts that crossed over large valleys were built as arched bridges or arcades. The use of the inverted siphon was perhaps one of the more interesting architectural features of Roman aqueducts. An inverted siphon was constructed to cross a low point and featured a closed pipe laid against the valley floor. One end of the pipe rested at a higher elevation than the opposing end thereby pushing the water through the pipe without a need to build an arch or arcade to facilitate water flow.[11] Eventually as the Roman Empire crumbled aqueducts were still used until they eventually fell into disrepair.

Pont du Gard aqueduct in France

[edit] Modern Day Aqueducts

During the Renaissance, interest in aqueducts was rekindled. By 1582, the very first public waterworks system was thought to have been built in London. The system used a number of pumps to fill up a reservoir and pressure generated from gravity forced the water through a labyrinth of wood pipes. A similar type of hollow wood pipe waterworks system was built in the U.S. in Boston around 1652.[12]

As a result, the construction of aqueducts was quite extensive during the 19th century. Brick and concrete were used to fabricate open channels and conduits and the use of cast iron now readily available was used to create inverted siphons under high pressure.[13]

The invention of the steam engine also was instrumental in vastly improving waterworks productivity that had previously relied on horse-driven power pumps to move water through the pipes. Iron pipes also eventually replaced wooden pipes.[14]

[edit] How it Works

Unlike ancient aqueducts constructed of natural materials such as wood or bamboo and masonry, the construction of aqueducts today can be a mammoth undertaking. The largest modern day aqueducts today are based in the United States. The Catskill Aqueduct built in the state of New York is 120 miles (193 km) long and delivers 1,130 cubic feet (32 m3)per second. The Colorado Aqueduct in southern California feeds Los Angeles and its outlying communities with 1,872 cubic feet (53 m3) per second from the Colorado River nearly 250 miles (402 km) away.[15]

Today’s aqueducts are constructed with large concrete pipes and rely on electricalloseerrand pumps to elevate and move water so it flows more steadily through miles and miles of concrete pipes network together and situated deep under the ground.[16] These huge concrete pipes are prefabricated in a factory and then laid on a gravel bed on the bottom of a trench or ditch that has been dug out by big earthmoving equipment. The pipes are grouted together and then the trench covered with backfill. Water is then stored is a man-made lake called a reservoir. Water goes through purification process to clean it before it is pushed down the huge main pipe by huge electrical pumps. Smaller pipes branch out from the large main pipe like a tree carrying the water to various locations all over a city. Additional computer controlled, electrical pumps are used to regulate the consistent flow of water. The water is eventually piped into buildings for people to use.One thing that has remained the same is that today’s aqueducts are still dependent upon the same hydraulic principles that govern water flow as did ancient aqueducts. hahahha

[edit] References

  1. Aqueduct. Blurtit.com. 2008-09-09.
  2. Aqueduct. Blurtit.com. 2008-09-09.
  3. Aqueduct. Answers.com. 2008-09-09.
  4. Aqueduct. Encyclopedia. 2008-09-09.
  5. Aqueduct. Blurtit.com. 2008-09-09.
  6. Aqueducts. Facstaff. 2008-09-09.
  7. Aqueduct. Blurtit. 2008-09-09.
  8. Aqueducts. Facstaff. 2008-09-09.
  9. Aqueduct. Bookrag. 2008-09-09.
  10. Aqueducts. Facstaff. 2008-09-09.
  11. Aqueducts. Facstaff. 2008-09-09.
  12. Aqueducts. Facstaff. 2008-09-09.
  13. Aqueduct. Encyclopedia. 2008-09-09.
  14. Aqueducts. Facstaff. 2008-09-09.
  15. Aqueduct. Encyclopedia. 2008-09-09.
  16. Aqueduct. Encyclopedia. 2008-09-09.