Venturi flume
![Diagram of a Parshall flume, showing free-flow and submerged flow operating regimes](/Images/godic/202502/19/Parshall_Flume.svg5019.png")
A venturi flume is a critical-flow open flume with a constricted flow which causes a drop in the hydraulic grade line, creating a critical depth.
It is used in flow measurement of very large flow rates, usually given in millions of cubic units. A venturi meter would normally measure in millimetres, whereas a venturi flume measures in metres.