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Flume

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Log flume in Sweden, August 2010

A flume is a human-made channel for water, in the form of an open declined gravity chute whose walls are raised above the surrounding terrain, in contrast to a trench or ditch.[1][2] Flumes are not to be confused with aqueducts, which are built to transport water; flumes use flowing water to transport materials.[citation needed] Flumes route water from a diversion dam or weir to a desired materiel collection location. Flumes are usually made up of wood, metal or concrete.

Many flumes took[when?] the form of wooden troughs elevated on trestles, often following the natural contours of the land. Originating as a part of a mill race, they were later used in the transportation of logs in the logging industry, known as a log flume. They were also extensively used in hydraulic mining and working placer deposits for gold, tin and other heavy minerals.

Etymology

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The term flume comes from the Old French word flum, from the Latin flumen, meaning a river. It was formerly used for a stream, and particularly for the tail of a mill race. It is used in America for a very narrow gorge running between precipitous rocks, with a stream at the bottom, but more frequently is applied to an artificial channel of wood or other material for the diversion of a stream of water from a river for purposes of irrigation, for running a sawmill, or for various processes in the hydraulic method of gold-mining.[3]

Types of flumes

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Bull Run Hydroelectric Project diversion flume, carrying water from one reservoir to another
Working irrigation flume under repair in the East Kootenay, British Columbia Canada. Built in 1912, it runs 8 km to provide water to a few dozen farms.

Millrace

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A diversionary flume is used to transfer water from one body to another, such as between two reservoirs.

Log flume

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Log flumes use the flow of water to carry cut logs and timber downhill, sometimes many miles, to either a sawmill or location for further transport.

Flow measurement flume

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Some varieties of flumes are used in measuring water flow of a larger channel. When used to measure the flow of water in open channels, a flume is defined as a specially shaped, fixed hydraulic structure that under free-flow conditions forces flow to accelerate in such a manner that the flow rate through the flume can be characterized by a level-to-flow relationship as applied to a single head (level) measurement within the flume. Acceleration is accomplished through a convergence of the sidewalls, a change in floor elevation, or a combination of the two.[4]

Flow measurement flumes typically consist of a converging section, a throat section, and a diverging section. Not all sections, however, need to be present. In the case of the Cutthroat flume, the converging section directly joins the diverging section, resulting in a throat section of no length (hence the term "Cutthroat"). Other flumes omit the diverging section (Montana, USGS Portable Parshall, and HS / H / HL flumes).[5]

Flumes offer distinct advantages over sharp-crested weirs:[4]

  • For the same control width, the head loss for a flume is about one-fourth of that needed to operate a sharp-crested weir
  • The velocity of approach is part of the calibration equations for flumes
  • Unauthorized altering of the dimensions of constructed flumes is difficult (and therefore unlikely)
  • Most flume styles readily allow for the passage of sedimentation and floating debris – reducing the time and effort associated with maintaining a flume installation

Styles of flow measurement flumes include: Cutthroat, HS / H / HL-type, Khafagi, Montana, RBC, Parshall, Palmer-Bowlus, Trapezoidal, and Venturi Flume.[citation needed]

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A bypass flume on the Chesapeake and Ohio Canal

In some nineteenth-century canals, a bypass flume diverted water around a lift lock from the level (or pound) above to the level below the lock, so that the level below would have sufficient water.[6]

Recreational flumes

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In competitive swimming, specialized flumes with transparent sides are often employed by coaches to analyze a swimmer's technique. The speed of the flow is variable to accommodate the full spectrum of swimming styles and ability.

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See also

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References

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  1. ^ Koester, Frank (1909). Hydroelectric Developments and Engineering. New York: D. Van Nonstrand. pp. 40–45.
  2. ^ Guidelines for Identifying, Evaluating and Registering Historic Mining Sites. Washington, D.C.: National Park Service, U.S. Department of the Interior. 1997.
  3. ^  One or more of the preceding sentences incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). "Flume". Encyclopædia Britannica. Vol. 10 (11th ed.). Cambridge University Press. pp. 574–575.
  4. ^ a b Flumes, Openchannelflow.com
  5. ^ Sections of a Flume - Their Location and Function, Openchannelflow.com
  6. ^ Kytle, Elizabeth (1983). Home on the Canal. Cabin John, MD: Seven Locks Press. ISBN 978-080185328-9. p. 270

Further reading

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