While they are one of the more modern styles of flumes (developed in the 1960's), the Trapezoidal flume has been shown to have a nubmer of distict advantages, making it well suited to a variety of industrial and surface water measurement applications.

Retrofit Easily Into Natural Channels / Creeks / Streams

Naturally formed channels / creeks / streams tend to take on a Trapezoidal cross-section shape as the erosive force of moving water sculpts the earth over which it flows.  The Trapezoidal flume was specifically designed with this in mind.  The cross-section of the flume means that installation costs are less than with rectangular or U-shaped flumes.

Accurate over a Wide Range of Flows

Trapezoidal flumes provide both sensitivity in measuring low flow rates as well as the ability to pass large, surge flows.  While resolution (change in head for a given change in flow) decreases as the depth if the flume increases, the flume still exhibits the same accuracy (+/- 3-5%) over its rated range.

Self-Cleaning Design

Trapezoidal flumes we designed to be self-cleaning.  The flat bottom of the flume means that silt will not settle out, building up on the flume floor (as can happen with ramp style flumes).  The ever widening V-shape of the flume also means that larger solids tend to pass through the flume as the flow rate increases.  Should debris lodge in the flume, the water that builds up behind the obstruction tends to dislodge it, allow it to flow out of the flume.

Wide Range of Styles / Sizes

While Trapezoidal flumes are similar in configuration in that they have outward slopping walls, a flat bottom, and converging throat, a number of different styles and sizes have been developed since the 1960’s, meaning that for most irrigation, edge-of-field, seepage, and industrial discharge applications there is a Trapezoidal flume to accurately measure the anticipated flows.

Minimal Head Loss

The Trapezoidal flume generates, as a whole, the smallest amount of head loss of any short throated flume type.  The flat bottom means that it can sit directly on the floor of most channels, while the outward opening sidewalls mean that the flume can pass large flows. 

Resistance to Submergence

Trapezoidal flumes are particularly resistant to the effects of submergence (where downstream conditions restrict the free flow of water out of the flume).  Regardless of the Trapezoidal flume style / size, the submergence transition is 80%.

 

While not as versatile as some other flume types (notably the Parshall flume), the Trapezoidal flume is well suited to applications where head loss is critical, where the flow rates will widely vary, or where solids are an issue.