A Parshall flume has a special shaped open channel flow section which may be installed in a ditch ,canal, or lateral to measure the flow rate. The Parshall flume is a particular form of venturi flume and is named for its principal developer, the late Mr. Ralph L. Parshall (Water Measurement Manual, U.S. Bureau of Reclamation, 1984)."

Ralph L. Parshall saw problems with stream measurements when he began working for the USDA in 1915, as an irrigation research engineer. In 1922 he invented the flume now known by his name. When this flume is placed in a channel, flow is uniquely related to the water depth. By 1953 Parshall had developed the depth-flow relationships for flumes with throat widths from 3 inches to 50 feet. The Parshall flume has had a major influence on the equitable distribution and proper management of irrigation water


Parshall flumes are apparently the most widely used types of flumes now for fixed flow monitoring installations. They have wide flow ranges, resistance to submersion,and are simple to calibrate..
Parshall flumes are sized by throat width and conform to standardized dimensions published in the U.S. Department of the Interior, Bureau of Reclamation.