Waterfall design weir/spillway dimensions

[GaryMoz]

And yet another question

I'm probably way overthinking this but with design i building I don't have much room for mistakes, I'm going to have a liner made and fitted, so just trying to minimise mistakes where I can.

So I have a raised bog filter area that will feed into a pond. See below, it's a bout a 10" drop with a flow rate of 5000gph. I just realised I have no idea what size waterfall opening should be, both the width and depth or even if I should shape the flow into and over the waterfall. In my mind I was thinking of getting a flat stone to act as the "spillway" for the water flow over. It doesn't matter if it's not a perfect edge as I want the water to breakup over the waterfall. However what width should it be? How far below the desired bog water level should the top of the stone be. Can anyone recommend sites or documents that can help me. All I know at the moment ideal flow rate is 120 -150 gph per inch width, which would give a waterfall around 40" across probably a bit wider than I was thinking, What would happen if I made it 20", would the level in the bog rise? etc etc. head spinning, all I wanted was hole in the ground with water and fish

Thanks

 

[Mmathis]

Hello, I do hope you can help me. I do not have a pond, it is a water wall that is 8 feet wide x 4 feet high x 3 feet deep. I am using a submersible water pump to pump water to the wall's height and run back into the basins. There are 2 separate 55-gallon water basins. Although the water will return to the basins, I wonder if the return will cause enough movement in the water to give adequate circulation (movement) in the body of the water. If this is not adequate, I would greatly appreciate your suggestion for what I should do. Thanks so much.

@carlene I see where you have posted this same question (as a comment) under several posts. Your question will probably get lost among all other responses. You might get a better response if you make a new post, and post your question as a separate post.

 

[GaryMoz]

I've managed to find some online calculators which I can use to estimate width and depth based on flow rate.

At 5000gph, for the waterfall width of 24" the water depth would be 1" does that sound right?

I think there is a video somewhere that's shows different flow rates over a water falls, I'll try to find it

 

[drjay9051]

I've managed to find some online calculators which I can use to estimate width and depth based on flow rate.

At 5000gph, for the waterfall width of 24" the water depth would be 1" does that sound right?

I think there is a video somewhere that's shows different flow rates over a water falls, I'll try to find it

Gary:

 

[drjay9051]

I tried to link a video of my waterfall with a 23.Inch spillway and 3900 gallons per hour, but I can't seem to upload it anyway.Believe me, it is loud fast and beautiful.Yes, there is video comparing flow rates.I will look for that as well

 

[j.w]

I tried to link a video of my waterfall with a 23.Inch spillway and 3900 gallons per hour, but I can't seem to upload it anyway.Believe me, it is loud fast and beautiful.Yes, there is video comparing flow rates.I will look for that as well

Most go to youtube to post the vids and then allow them to be shared here. Must be set to public viewing on youtube tho.

 

[GBBUDD]

And yet another question

I'm probably way overthinking this but with design i building I don't have much room for mistakes, I'm going to have a liner made and fitted, so just trying to minimise mistakes where I can.

So I have a raised bog filter area that will feed into a pond. See below, it's a bout a 10" drop with a flow rate of 5000gph. I just realised I have no idea what size waterfall opening should be, both the width and depth or even if I should shape the flow into and over the waterfall. In my mind I was thinking of getting a flat stone to act as the "spillway" for the water flow over. It doesn't matter if it's not a perfect edge as I want the water to breakup over the waterfall. However what width should it be? How far below the desired bog water level should the top of the stone be. Can anyone recommend sites or documents that can help me. All I know at the moment ideal flow rate is 120 -150 gph per inch width, which would give a waterfall around 40" across probably a bit wider than I was thinking, What would happen if I made it 20", would the level in the bog rise? etc etc. head spinning, all I wanted was hole in the ground with water and fish

Thanks

View attachment 162464

It will rise alright a 20 inch weir at 5000 will double the height of which the water will backup and rise. Making for a thicker flow falling. Not that this is unmanageable. I have ball valves or as you bits prefer gate vales everywhere so I can control intake and return. My waterfall is is a solid 3 feet wide and I throw 8 to 10000 gph over the falls. Could it be a solid sheet flow yes but like your self I was not looking for a solid wall of water. I'm a solid 2 inches high where the water drops from the upper pond but the opening is only about a foot wide. If you did do a perfectly level weir with a sheet of metal where it's bone dead level and a perfect sheet flow you could probably get a 40 inch to look ok. but the 20 for 5000 would be my choice again with a ball valve you can lesson how much water goes to the falls . The slower the water goes through the bog the better .