How to Use Your Parshall Flume
Under normal conditions, the only things you need to use a Parshall flume are:
- A flume (naturally)
- A long enough ruler (many of the popular sizes of Parshall flumes are 3-feet deep)
- And an eyeball (two if you have ‘em)
Technically you don’t even need water flowing through the flume!
The Parshall flume works by accelerating slowly flowing water in such a way that:
at one specific point (called the point of measurement or Ha if you want to be technical) the depth of the water corresponds to the flow rate through the flume
So, by measuring the depth of water at the point of measurement you can look up the flow rate either on a flow chart for the flume or you can do some math and plug the level into the flow equation.