You can have any number of outlet devices on a pond. This can include one or more "compound" outlet structures, such as a riser. For a single riser you might have:
Device#1=Culvert, Routing=Primary (the culvert barrel)
Device#2=orifice, Routing=Device#1 (side openings in riser)
Device#3=orifice, Routing=Device#1 (top of riser)
If you wanted to add a second riser you could add:
Device#4=Culvert, Routing=Primary (the culvert barrel)
Device#5=orifice, Routing=Device#4 (side openings in riser)
Device#6=orifice, Routing=Device#4 (top of riser)
If you want separate routing and reporting for the second riser simply change the routing on Device#4 to Secondary.
For details please see
Peter Smart
HydroCAD Software