Hydrocad Pond Flow Question. Is my Boss wrong???
Hydrocad Pond Flow Question. Is my Boss wrong???
(OP)
Hello,
I have been modeling with hydrocad, hydraflow, and pond pack for years. I have occasionally encountered situations where the incoming flow is less that what is leaving the pond. This may occur during a large storm event when the water is flowing out of a low flow orifice and building up depth until it just spills over the crest of a large spillway. At that time i have seen spikes of peak flow be larger than the peak flow entering the pond.
My boss reviewed my latest project and tells me that this is NOT POSSIBLE and told me to look at the model. Can someone please let me know that this is possible and provide a scientific reason why? Thank you very much.
I have been modeling with hydrocad, hydraflow, and pond pack for years. I have occasionally encountered situations where the incoming flow is less that what is leaving the pond. This may occur during a large storm event when the water is flowing out of a low flow orifice and building up depth until it just spills over the crest of a large spillway. At that time i have seen spikes of peak flow be larger than the peak flow entering the pond.
My boss reviewed my latest project and tells me that this is NOT POSSIBLE and told me to look at the model. Can someone please let me know that this is possible and provide a scientific reason why? Thank you very much.





RE: Hydrocad Pond Flow Question. Is my Boss wrong???
As a wild guess, you have failed to provide storage data above the crest of the spillway. For details please see www.hydrocad.net/overfilled.htm
If you have further questions please post your HydroCAD project file or email it to HydroCAD support.
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
Now there are certainly times in many models where the instantaneous inflow is lower than the instantaneous outflow, but not peak to peak.
Echo checking to make sure you're not pegging your storage out somewhere, and there's no wobble in your hydrographs.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
a. upstream watersheds raise tailwater before substatial runoff for subject watershed
b. subject watershed fills pond which has outflow limited by tailwater (could even be zero or reverse flow)
c. storm event ends and tailwater quickly dissipates
d. surcharged pond is allowed to outflow freely
The peak inflow to the pond over the entire event could be a small fraction of the peak outflow in this scenario.
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
andy
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
Of course, we're all speculating on what might be happening in your model. The only way to know for sure is to look at your model. There are a lot of issues that could be involved.
BTW: There is no need to "assign a pretend 0.001% slope" to a culvert. You can use a zero or even a negative (adverse) slope for a culvert in HydroCAD. If the zero slope is causing you problems, there is probably another factor at work.
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
I must beg to differ regarding the pipe slope problem. I am using hydrocad 9.0 and when i enter a negative slope, the slope is highlighted in RED and it says X - Inlet must be higher than Outlet, and you cannot physically "APPLY" the data. You cannot close this window until you cancel or apply a Positive slope. Can you please try this and get back to me?
I have attached an image of the error message.
RE: Hydrocad Pond Flow Question. Is my Boss wrong???
But a culvert (outlet on a pond) definitely can have an adverse slope, and this is the way most pipes should be modeled.
For details see www.hydrocad.net/pipes.htm
Peter Smart
HydroCAD Software
www.hydrocad.net