Trapezoidal Flume Design

The Trapezoidal Flume has a V-shaped cross-section and flat floor.  

When flows are low and flowing through the “point” of the V, a relatively large amount of head (level) is generated, as the crest width of the water is small – providing low flow sensitivity and accuracy.  

As the flow increases, the effective crest width increases (the V expands outwards) giving the Trapezoidal Flume the ability to measure higher flows.   

The ability to accurately measure low and high flows without the need for a change in channel / floor elevation (e.g. Parshall) or free-spilling discharge (e.g. H Flume) make the Trapezoidal Flume unique.

Trapezoidal Flume Dimensions

The dimensions for most Trapezoidal Flumes used today can be found in three publications:

• Robinson, A., Trapezoidal Flumes for Measuring Flows in Irrigation Channels, USDA-ARS 41-140, March 1968
• Robinson, A., Measuring Water in Small Channels with WSC Flume, Washington Agricultural Experiment Station, Circular 200, 1952 
• Robinson, A., Water Measurement in Small Irrigation Channel Using Trapezoidal Flumes, Transactions of the ASCE, Vol. 9, No. 3, 1966 

​The dimensions are Trapezoidal Flumes are not standardized in a national / industry standard as is the case with other flumes (e.g Parshall).

 

TRAPEZOIDAL FLUME MASTER DIMENSIONS DRAWING