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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: Distance between the staff gauge and the observer The angle at which the gauge must be…

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…

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…

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. Openchannelflow staff gauges are availalbe in a range of:…

On the face of it, mounting a staff gauge on a weir plate to get the head / flow rate seems like a good idea.  It works for on a flume, why wouldn’t it work on a weir? The problem is, as we have seen earlier, the water level in a weir pool draws down as the flow…

A common problem in using weirs to measure water flows is reading the flow level too close to the weir plate.  To understand why this is a problem we need to look at what happens as flow travels through the weir pool and then over the weir crest. In a properly formed,…

We often talk about how OCF tried to sweat the small things.  One of the items that we have focused on is our flow meter sensor mounting brackets.  Many of the designs currently on the market show, what we believe to be, a "good enough" philosophy - that the brackets…

The freeboard is the difference in height between the top of a flume or weir and the highest water level anticipated. Freeboard is a guard against overtopping by waves, unexpected rises in the water level, or miscalculation in the maximum anticipated flows.  Freeboard is…

One problem that we see again and again is how to measure open channel flow in partially full pipes.  For applications where a device can extend off the end of the pipe a number of solutions are used, including:  California pipe (which is extends  vertically up…