About Parshall Flumes
Developed in the 1920's at the Soil Conservation Service by Dr. Ralph Parshall, the Parshall (Improved Venturi) flume was intended to overcome the limitations of the devices of the time used to measure irrigation flows and water rights.
Over time, the Parshall flume has grown into a class of 22 flumes and has seen it applied to a wide range of applications from water rights to sanitary flows.
Parshall flumes use a combination of contraction of the side walls with a drop (and recovery) in the floor elevation to accelerate open channel, non-critical flows of water in such a way that a known relationship between the level in the flume and the flow rate occurs.
Affordable and accurate to +/- 2-5% (under controlled conditions), the Parshall flume is a mainstay of the measurement of water flowing by gravity in open channels around the world.