How much water is this?

Otisd85

New Member
I have a pond and I'm trying to figure out how to determine how much water is coming out of the overflow culvert. It runs like this year round, and I'm thinking about a low head unit from Langston Alternative, but I'm not sure how to figure out if the pond will support a 6" siphon.org_60e222d085039d09_1584302904000.jpgScreenshot_20210122-162936_Gallery.jpg
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Otisd85

New Member
I appreciate the suggestion, but I think it's too much water for a bucket test. The stream coming out of the culvert is wider than a bucket, and I'm pretty sure it would fill the bucket instantly. I doubt I could hold on to the bucket and don't think I could time it accurately. Also, I'd have to do it from a boat.
 

The Lift Guy

Making the impossible possible
Perhaps a bigger bucket is in order? Like a 55 gallon drum might have a wide enough mouth, or a 70 gallon plastic storage container
 

Otisd85

New Member
A 55 gallon drum may be more feasible. I'll have to see if I can float it out there and try to time how long it takes to fill and sink.
 

Hedges

Photon Sorcerer
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Just float it, and slip it under the waterfall. Use a stopwatch.

The Lift Guy's suggestion should work too. Float a drum up to it, shove against pipe. Before it overflows, pull off to one side and measure depth.
 

Hedges

Photon Sorcerer
I suggest routing the 6" pipe to four nozzles on the turbine, 2 always on and the other two controlled by an electric valve and float switch in the pond. It should get 100% for a wider range of flow that way.

Oh, sorry. I'm thinking of a Pelton wheel. Their low head unit doesn't look like you can run with varied flow that way.
 

Darkstar

Rain Wrangler
That pipe is a circular weir. Use a circular weir formula or online calculator.




I have a pond and I'm trying to figure out how to determine how much water is coming out of the overflow culvert. It runs like this year round, and I'm thinking about a low head unit from Langston Alternative, but I'm not sure how to figure out if the pond will support a 6" siphon.View attachment 34192View attachment 34191
View attachment 34188
 

Maast

Compulsive Tinkerer
You'll need to set up a "V notch weir" and measure high up it goes, then you can accurately calculate how much water is going through.
 

Otisd85

New Member
I suggest routing the 6" pipe to four nozzles on the turbine, 2 always on and the other two controlled by an electric valve and float switch in the pond. It should get 100% for a wider range of flow that way.
I don't think i have enough head for that type of setup. It's only about 10' from the surface of the top pond to the surface of the lower pond.
 

Otisd85

New Member
I've come across info about v notch weirs but that's the first I've seen of a circular weir, I'll have to look into that more. I wasn't confident in doing the math for a weir, but if I can get a base estimate with a bucket test using a 55 gallon drum and it seems like it's going to be enough water, I think I'll build a weir to double check my work and compare my numbers between my two tests.

Thank you to everyone for the suggestions.
 

Otisd85

New Member
You would want to measure the water on the pond side or intake side of the pipe if you use the weir method...
You don't think a v notch weir would be accurate on the end of the culvert?
I know nothing about weirs, that's why I'm asking. It's the same water going in as it is going out, isn't it? If I built a weir on the top side, I'll have to raise the water level by the amount the weir comes up.
 
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schmism

Solar Addict
weirs work, however you have to know how to install them and do the math for them Which is why the bucket test is typically the fall back for "small" flow rates.
 
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