Blog

Seepage through, below, or around an embankment dam is a critical indicator of the health and condition of the dam. The amount of seepage is normally directly related to the water level in the reservoir. However, any sudden change in the amount of seepage without an apparent…

As we have seen before, a Modified Parshall Flume (aka USGS Portable Parshall Flume) is a Parshall flume with the discharge section removed. Removing only the discharge section still allows for submergence calculations to be performed – unlike the true Montana flume where…

There is a common misconception of what does and does not constitute a Montana Flume. For some, a Montana flume is a Parshall flume with the discharge removed. For others, it is a Parshall flume with the throat and discharge removed. The US Department of the Interior Bureau of…

In 1994, Dr. Fred Blaisdell published an evaluation of the data collected by Dr. Parshall on his namesake flume. As part of the evaluation, Dr. Blaisdell tested both full size and scaled Parshall flumes to validate the ratings of 6-foot, 10-foot, and 15-foot flumes.

The streamlines through a Parshall flume are assumed to be both parallel to the flume walls and continuous (Parshall 1936). Many things can disrupt parallel streamlines as they enter the flume, including: upstream debris, bank vegetation growing into the upstream channel, and…

For a short-throated flume to accurately measure flow, it is desirable to keep the flume’s dimensions with +/-2% of nominal. But what happens when they aren’t? For Rectangular Cutthroat Flumes, investigations have shown that corrects for throat width can be made.

The Parshall flume is a fixed hydraulic structure originally developed to measure surface water and irrigation flows. Recently, research has been conducted to see if Parshall (and Venturi) flumes also provide a benefit in aerating the flow streams that they are used to measure.…

As Parshall Flumes get larger they become more restricted in their uses. The 72-inch Parshall Flume is primarily used to measure flows at treatment plants, water rights, and surface waters. Due to its size, the 72-inch Parshall Flume usually ships in two pieces. The 72-inch…

48-inch Parshall Flumes have been used over the years to measure flow in a several different applications mine dewatering, surface waters, stream, rivers, water rights, and wastewater treatment plants. The 48-inch Parshall Flume is useful in a number of applications:

The 1-inch Parshall Flume is the smallest of the 22 standard Parshall flume sizes. The small size means that it is relatively limited in its use. 1-inch Parshall Flumes cannot be used on unscreened sanitary flows as they will clog. The 3-inch Parshall Flume is the smallest…

The Extra Large 60º V Trapezoidal Flume is useful - providing good low-end accuracy while still allowing connection to larger (up to 12-inch [30.48 cm]) pipes. The flat-bottomed design and v-shaped cross section mean that the flume passes solids well. The Extra Large 60º V…

Unlike the Palmer Bowlus flume which was specifically designed to be used in-line with sewer pipes and conduits, Parshall flumes were originally developed to measure flows in irrigation channels and natural streams / rivers. Over the years, though, Parshall flumes have been…