Hello, I have a project where I ha 1

[BCivil2]

Hello,
I have a project where I have a ditch that flows 100cfs. I need to divert off 20cfs of flow from that channel. Ideally, the 20cfs would be 'preferred', meaning that if the ditch only flows 19cfs, all 19 cfs goes to diversion. What is the best way to do this under open channel conditions? My thought was to install a stilling basin with an orifice sized to handle 20cfs at a certain elevation (call it H-20). Then I'd install a large broad weir at H-20. This would keep the driving head of the orifice from increasing too much.
Welcome thoughts (especially if anyone has done this type of thing before).
Thanks!

 

[rowingengineer]

The way you describe is how I would typically handle.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[cvg]

you are describing an irrigation check / turnout structure. look at USBR design of small canal structures

http://www.usbr.gov/pmts/hydraulics_lab/pubs/manuals/SmallCanals.pdf