Coupled pond mystery flow
Coupled pond mystery flow
(OP)
I'm running HydroCAD 8 and am hitting a snag. I have two ponds, each about 1 square mile in size, that are connected by a 48" pipe. I am proposing a new structure in the downstream pond that will have an invert 10' above the connecting pipe. When I select the higher invert as a starting elevation, I start to have problems with the flow.
I need to assign the same starting water level to the upstream pond as the downstream, since they're connected. Stor-Ind routing didn't give me the error for tailwater, but I think the tailwater does have an impact. DSI and Sim Route show 130 cfs leaving the upper pond, but the summary shows no water going through the culvert (even if I model a reverse flow).
My concerns are that the stage discharge table shows heavy flows starting to occur 2' below my starting invert elevation. This combined with the culvert not showing any flow happening has me wondering if I'm asking HydroCAD to do a function that it can't handle. Or have I missed the obvious???
I need to assign the same starting water level to the upstream pond as the downstream, since they're connected. Stor-Ind routing didn't give me the error for tailwater, but I think the tailwater does have an impact. DSI and Sim Route show 130 cfs leaving the upper pond, but the summary shows no water going through the culvert (even if I model a reverse flow).
My concerns are that the stage discharge table shows heavy flows starting to occur 2' below my starting invert elevation. This combined with the culvert not showing any flow happening has me wondering if I'm asking HydroCAD to do a function that it can't handle. Or have I missed the obvious???





RE: Coupled pond mystery flow
Make sure you set the starting elevation in both ponds. As long as there are no warning messages, the results should be valid. If you do have problems, you can send the file to HydroCAD support.
Also consider: If the interconnection between the ponds is large in comparison to the final (higher) outlet, then the two ponds will always be equalized, and are more easily modeled as a single pond, ignoring the interconnecting pipe.
RE: Coupled pond mystery flow
RE: Coupled pond mystery flow
If you still have questions please email your file to HydroCAD support.