Estimating Flow Rate using the Float Method

A common but simple method for measuring flow rate through an open channel is the Float method. Although not as accurate as a measuring device such as a flume or a velocity probe, the float method can provide an educated estimate. Briefly put, this method involves measuring the surface velocity of the water with a floating object, and then multiplying this velocity by the width and average depth of the channel.
"The accuracy of float methods are limited by many factors, including a lack of preciseness in the coefficients, too few stream segments being used, appreciable changes in stream depth along the test reach, oblique currents, wind forces, and experimental errors in measuring time and distances. Often, a number of people are required to perform this technique and make observations. The course of the floats is difficult to control, and they can be easily retarded by dragging on submerged debris and on the sides and bottom of the channel." (USBR)
US Bureau of Reclamation document - www.usbr.gov/tsc/techreferenc...
See the calculator, instructions, and worksheet on our website at inmtn.com/float.
We are a distributor for irrigation and weather monitoring supplies. Find us at inmtn.com.

[@AayushKumar-ci5pm]

Simple and correct explanation for understanding float meter method. Thank you, sir

[@KakNa.05]

Thanks for saving our bums for geography class with your clear explanation and steps. 10/10

[@mehmetozalp8148]

Thanks for the simple and understandable explanation and application of discharge measurement

[@varmavarma6663]

Perfect demonstration for this topic because, it is easy to understand perfectly and simply....

[@cocoachanie]

I loved this. thank you for the clear demonstration

[@mattdathew2794]

Thankyou very much .. most in depth I've found so far

[@Bobby14221234]

This is good as it measures an actual flow - thanks

[@yasirmahsud4129]

Simply perfect...

[@gomezanzolajuansebastian2794]

hello a question, I would like to know how is the right of the windlass elice, against the current or in favor of the current?

[@juliethmosha8885]

Nice explanation

[@davidtechi6494]

Thank you much love

[@donaldpaivu6901]

Thanks very helpful.

[@sireeshaajjarapu4057]

This is right time video for me thank u so much

[@osamakh7062]

Good job

[@nithinhm1757]

Thanks a lot for doing this video🌟
I have a small Doubt for the 0.85 roughness value. how will you actually calculate it on what basis

[@intermountainenvironmental3304]

We like to use the .85 value based on our experience. You can also view a document here that is more specific based on channel depths.
www.usbr.gov/tsc/techreferences/mands/wmm/chap13_10.html

[@abdussamadkhan5705]

Thanks

[@donnyburns486]

Hi! I plan on doing this some time next year with an ourtdoor social group and would love to get ahold of the documents you had posted. The website is no longer up. Thanks!

[@Kevin-rp4vs]

Great video, but you should always stand downstream of the depth stick for accurate measurements.

[@intermountainenvironmental3304]

Or behind it as in the video :)

[@yolloy2372]

Is surface speed same as underneath? Obviously not. But is it neglectable?

[@ST-rj8iu]

no. He knocked off 15% from the surface speed.

[@rso823]

Does any float go downstream at the same speed for example like a rubber duck or a peice of paper would? does mass matter

[@rso823]

Also wind speed

[@724riff]

So I'd like to ask. If a person put bolders let's say roughly 10 feet on each side of that exact spot how would it affect this whole equation.

[@724riff]

For example if that was 1000 gallons over the roughly 42 feet he stated and now it's a 1000 gallons over roughly 20 feet because of the boulders would it increase the water speed with tye same amount of water and make it more worthy of hydro electricity or not

[@aldrinbantilan4457]

what if it is a waterfalls?

[@joshhanks744]

You can also use the Flow Probe as seen in this video.
ruclips.net/video/jY9Jxe0N5jM/видео.html

[@intermountainenvironmental3304]

www.inmtn.com - we have many options for monitoring flow in rivers, streams, canals and pipes.

[@atoz6057]

0.85 sir

[@dr.muhammadmohsinwaqas4142]

Why 0.85 for velocity adjustment

[@AayushKumar-ci5pm]

As there some retardation on the bottom of channel for flowing of water . There is a difference in surface flow and bottom flow so , the hydrologist recommended to take the 85% for that thing