Blog

When the H flume was developed, analysis of the stage-to-discharge data showed that the flows could be characterized by three different equations: low flow, transitional flow, and main flow. Using those equations, though, was difficult in the field – and flow tables were…

While we often thing we seen it all, we are continually amazed by users. YouTube user Sidney Seckler has posted a video showing an unusual use for a Parshall flume: Chemical Mixing! Alum is added (as a coagulant) to the flow upstream of the flume. The flow is then accelerated…

YouTube user Javier Cornejo has posted an interesting video of a scale model of a dam and how flow can seep through it. The water on the upstream side of the dam has had dye added to aid in the visualization of the seepage through the dam. Additionally, as the seepage has…

Flumes are a common way to measuring water rights / irrigations flows on farms and ranches.

If you divert, store, or use water from a surface source or you divert water from a subsurface stream in a known and defined channel, California SB 88 requires that you report your diversion and use to the State Water Board, Division of Water Rights. This reporting is required…

With the adoption of SB 88 by the California State Water Board all smaller water users are now required to monitor and report the usage. This can be daunting. But take hope…all is not lost! At the center of any compliance program is the flow meter. For non-pumped sources, a…

On January 19, 2016 the California State Water Board adopted an SB-88: Emergency Regulation for Measuring and Reporting Water Diversions. The key provisions of the regulation call for all water rights holders to report their diversion and use of water annually. As the size of…

The traditional use for a staff gauge is to provide a visual way of determining the water level in some body of water (lake, river, flume, weir, etc.). Depending on the type of gauge, the level gradations can be anything desired - feet, meters, inches, yards, etc.

In the United States there are primarily two methods of apportioning the use of water by individuals or organizations (for the purposes of agriculture, farming, irrigation):

One of the most common questions that we receive is how much straight channel is required upstream of a Parshall flume. The answer is quite simple: Approach lengths shorter than the above may result in the velocity profile entering the flume not being uniform or there may be…

There are several components to measurement errors when using Staff (Level) Gauges to determine flow depth in a flume or weir. In general, staff gauge reading errors can be attributed to:

Previous studies into submerged flow and Parshall Flumes (Parshall, 1928 and Skogerboe, et al, 1967) lead to the development of submergence ratios (where flow transitions from free to submerged flow) and a corrected discharge equation. These ratios and corrected discharge…

For those unused to measuring seepage from embankment dams knowing when to measure can sometimes be challenging. In its Embankment Dam Instrumentation Manual, the Bureau of Reclamation lays out how frequently inspections should be made. Note that the table below indicates only…

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.

In conjunction with the State of Utah, the Utah Water Research Laboratory conducted a statewide study to determine the accuracy of flow measurement devices in Utah. Their investigations showed that 2/3rd of the devices (flumes, weirs, electromagnetic and ultrasonic flow meters)…

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.