Pond with overflow to ditch

[Nate100]

I'm trying to model a detention pond that outflows to a ditch through an orifice in a timber weir. My question is: What should my primary routing be for the pond outlet? I've got the orifice and the weir as device one in the "routing column". Should I model the ditch as a "culvert" for my primary routing and simply use a diameter for the culvert that reflects the cross sectional area of the ditch? Any ideas would be greatly appreciated.

 

[psmart]

I think you're confusing the device NUMBER (in the column with # sign) and the device ROUTING.

In your case, your outlet setup might be:

Device#1 = Orifice, Routing=Primary
Device#2 = Weir, Routing=Primary

Always use the default "Primary" routing to combine the flows. Other routing is used only for compound outlets like a riser structure. For details see

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

If the ditch is creating a tailwater effect, you can model this by routing the pond into a reach.