Submitted to: International Commission on Irrigation and Drainage Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2004
Publication Date: 6/1/2005
Citation: Wahl, T.L., Clemmens, A.J., Replogle, J.A., Bos, M.G. 2005 Simplified design of flumes and weirs. International Commission on Irrigation and Drainage Journal. 54:231-247
Interpretive Summary: The total demand for water in the Western United States exceeds the available supply. Our ability to determine the amount of water diverted for various uses is crucial. There are many locations where measurement of water is either inaccurate or difficult and expensive. An existing water measurement device for open channels, the long-throated flume, has been made more practical, more accurate, less expensive, more adaptable, and easier to design and calibrate due to the development of new software, called Winflume. The Winflume software provides a convenient method for design and calibration so that the flume can be adapted to the specific site. A new book has been written to describe the theory behind these flumes and to demonstrate the wide range of applications. This paper briefly describes these flumes, the book, and the software for interested users. It also provides calibrations for a number of standard flume sizes and shapes. These results should be of use to irrigation districts, consultants, municipalities, and federal agencies that deal with water issues, for example; the Bureau of Reclamation, Natural Resources Conservation Service, U.S. Geological Survey, etc.
Technical Abstract: Long-throated flumes and broad-crested weirs have become accepted standards for open-channel flow measurement during the past two decades. These structures offer the accuracy and reliability of critical-depth flow measurement, theoretically-based calibrations, the lowest head loss requirement of any critical-flow device, and extraordinary design and construction flexibility. Computer software developed in recent years has streamlined the design and calibration process. The software, WinFlume, has been described in several papers and a recent text. Although WinFlume is very easy to use, there is still a need for simplified design and calibration tools for situations where use of the computer model is not possible or desirable. This paper combines several previous efforts to provide such tools in both metric and English units for the most typical measurement applications encountered in irrigation and drainage systems. Pre-computed designs for trapezoidal broad-crested weirs, long-throated flumes with rectangular control sections, broad-crested weirs in circular pipes, V-shaped long-throated flumes, and portable RBC flumes are presented in easy-to-use tables that provide head and discharge ranges, construction dimensions, head loss requirements, and flume rating equation parameters. The use of the tables is demonstrated with examples, and construction methods are illustrated.