Detention Ponds w/ 2ndary Outlet

[MHMcLeod]

I am modeling a detention pond w/ a catch basin inlet set one foot above the floor of the pond, leading to a culvert whose invert is below the pond floor. When I add an emergency spillway as a secondary outlet, I get 0 cfs flowing through the inlet & culvert. If I remove the secondary spillway from the calculation, the pond outflow is subject to wild oscillations. Any ideas why this is happening & more importantly, how to correct it?

 

[MHMcLeod]

Never mind. I messed around w/ different discharge configurations until I got it to work, but if anyone has experienced all of their outflow bypassing an orifice, even though the max. elevation is well above the inlet, I'd be interested in knowing why.
Thanks.

 

[psmart]

You may have had the device routing set incorrectly. For details please see

http://www.hydrocad.net/pond1.htm

 

[queque]

In this case, the emergency outlet would be device #2. Is that correct?

 

[psmart]

Queque: I think you're confusing the device NUMBER with the device ROUTING. The left-most column with the # sign is the NUMBER. The Right-most column is the ROUTING. In this screen shot, devices 2 through 5 are all routed to device #1.

If you were to add another device it would be device number 6 (the next blank line.) The ROUTING would be set to indicate where the flow goes after passing through that device. For further details please see

http://www.hydrocad.net/pond1.htm