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Weirs are often described as “simple” and “low cost” ways of measuring open channel flows and, made of some materials they really are low cost. But this low cost comes at a price. Steel plate is frequently used to keep costs down and, when it is new, it’s a perfectly…

Weirs, like flumes, work by accelerating slow, sub-critical flow (Fr1). The acceleration develops a know relationship between level and flow upstream of the weir itself. But what happens when the flow approaching the weir isn’t sub-critical, but instead is critical or…

Measuring open channel (non-full pipe) flows in round pipes can be difficult when measurement costs need to be low or where power is not available at the site. There are proprietary weir inserts available, but they can be inconveniently sizes or insensitive or unrated for the…

YouTube user Pener Pã has posted an interesting video showing the installation of a Rectangular Weir Plate with End Contractions into a natural channel.

Pressure transducers are a popular method of measuring the water level in flume or weir installations. They are used by water resource managers, engineers, and hydrologists to monitor flow rates in a range of applications, including: agriculture (runoff and water use), watersheds…

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…

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.

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:

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…

For years Openchannelflow has offered staff gauges integrated into our flume, weir, and manhole products. Over time, though, we have been asked to expand our offerings to include free-standing Staff (Level) Gauges.