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The Parshall flume is the most widely used flume for measuring the flow of water in open channels and non-full pipes. The flumes have a number of distinct operational advantages, including:

The accuracy of the depth-discharge relations for Palmer Bowlus flumes in not considered to be constant over the full range of flows. The decrease in accuracy reflects the increased importance (and uncertainty) of the Coefficient of Discharge (Cd) at low flows.

Parshall flumes are restrictions in a flow stream that raise the upstream level as flow is restricted before passing through the flume. This backwater extends upstream of the flume, into the approach channel. The difference in the water surface elevation upstream of the…

The way to pick the right point of measurement in a Parshall flume is…not to pick at all!

Galvanized steel is commonly used for flumes and (somewhat less so) weirs in irrigation and water rights applications. Galvanized steel is economical and can provide a good useful lifespan.

Flat-bottomed Trapezoidal Flumes were first developed in the early 1960’s to be placed in canals. Their shape was chosen to more closely match that of the typical small canal shapes.

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.

Submergence in a flume occurs when downstream conditons combine to reduce free-flow out of the flume to the point where the free-flow discharge equations are no longer suitably accurate. While submergence corrections can be made for some flumes (Parshall, USGS Portable Parshall,…

We have worked with Water Rights Consultants, Ditch Riders, and Water Commissioners over the years and below are the most common problems that they encounter out in the field. The examples below use Parshall and Cutthroat flumes, but these problems are common to all flume types…

Long-throated Ramp Flumes like the Palmer Bowlus and the RBC can cause maintenance challenges when used on flow with high suspended solids contents or low flows. The problem is the way in which the flumes accelerate the flow from a sub-critical (Fr1) – whereby the level to flow…

In some applications (i.e. flat grades or the growth of vegitation) it is impossible or impractical to install a Cutthroat Flume so that it can operate under free-flow conditions. When such a conditon exists, the flume may need to be set so that it operates under submerged flow…

For a Flume to operate accurately, the flow surfaces must be kept free of debris and biological growth. In surface water applications, the growth of algae can present a considerable problem in trying to keep the flume clean. If a sufficient amount of algal growth is allowed to…