page_title: Flume
section_title: Flow measurement flume
hierarchical_section_title: Flume / Types of flumes / Flow measurement flume
caption_attribution_description: English: Time exposure while in Gold Creek 2
context_page_description: 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. Flumes are not to be confused with aqueducts, which are built to transport water, rather than transporting materials using flowing water as a flume does. Flumes route water from a diversion dam or weir to a desired materiel collection location.
  Many flumes took 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.
context_section_description: 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.
  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).
  Flumes offer distinct advantages over sharp-crested weirs:  
  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.
  Flow measurement flumes can be installed in earthen channels, concrete canals, below ground chambers, or factory integrated into Packaged Metering Manholes.
caption: Flume outflow
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