HydroCAD-Pond Routing in Series

[Vinnymaster117]

I am modeling a series of ponds; however, the discharge from the upstream ponds does not discharge to the surface of the downstream ponds. Instead, each upstream pond's discharge is being controlled by the culvert of the downstream pond’s outlet structure. For example, the controlled discharge from Pond A's outfall structure discharges into the culvert of Pond B’s outlet structure, and so on.

My challenge is that when I attempt to route them directly in sequence, the upstream pond’s outlet device discharges into the surface of the downstream pond rather than bypassing the initial outlet devices of the downstream ponds outfall structure and going straight to the culvert. How can I properly model this flow behavior?

Any help would be appreciated, thanks!

 

[psmart]

If I understand correctly, you would need to model the inside of the outlet control structure as a separate zero-storage pond, so that you can route the inflows accordingly. For example, working from the bottom up:

Pond 3 would be a zero-storage pond representing the inside of the control structure. Pond 3 will have a culvert outlet.

Pond 2 would be the actual pond storage, with a weir outlet, and routed to Pond 3.

Pond 1 can then be routed to the same Pond 3 control structure.

Repeat for any other upstream ponds. Basically, you're modeling this as a series of zero-storage catch basins. Each CB receives flow from the next CB upstream, plus the weir outflow from it's adjacent pond.

 

[Vinnymaster117]

Yes i believe you are understanding correctly. I created a quick and dirty illustration of what is happening, please see the attached PDF. In the scenario you described, would Pond 2 also need a culvert outlet or would the only outlet device be the weir? If I would need a culvert on both pond nodes, I would essentially be modeling that same culvert twice which is were I got hung up before.

Assuming that the culvert is only modeled on the Pond 3 zero storage node. My Pond 2 node would consist of an orifice and grate outlet. Would both of these devices be set primary routing? Previously, I always had my culvert set to primary and the remaining outlet devices routed to that culvert.

Thank you!

 

[psmart]

The weir and orifice can both be primary, routed to the control structure. Just one culvert, leaving the control structure. Don't include anything twice.