The two most common methods of determining the discharge of a flume are flow-measuring flumes and measuring weirs. In both methods, there is a fixed relationship between discharge depth and discharge capacity.
Flow-measuring flumes are mainly used in wastewater treatment plants because they are well suited for contaminated water. They can be easily maintained.
Parshall flumes are venturi flumes with a profiled bottom. The ratios of constriction and enlargement are defined. Parshall flumes are commercially available as a complete component including a discharge curve (discharge as a function of the discharge depth in the upstream water). They are widely used in North America.
The Parshall flume HM 161.55 consists mainly of two transparent side elements and the profiled base plate. The transparent side elements allow to clearly observe the processes in the flume.