Modelling Multiple Ponds in Series

[cassandtim]

I'm a complete newb here but need to know how to model 2 ponds in series.

The scenario is:

Both ponds have the same bottom elevations and the same top elevations and are connected by a culvert sized to handle the peak CFS with room to spare. The second pond has an orifice outlet.

I am unable to get the ponds to equalize and have the same peak elevation.

I am using HydroCAD 8.00

Any help will be greatly appreciated.
Thanks
-T

 

[psmart]

If the connecting pipe is big enough to keep both ponds at the same elevation (ie the connecting pipe is much bigger than the orifice) then you can model this as a single pond with two storage definitions and an orifice outlet. If you wish, you can even include the connecting pipe as a third storage definition (but don't list it as an outlet device.) See

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

If you need to model them separately, then use a culvert outlet on the first pond, and route the outflow directly to the second pond with the orifice. Pay attention to any warning messages and follow their advice to correct any problems. This will include switching to a tailwater-sensitive routing procedure, such as the dynamic storage-indication method. For details see

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

If you still have questions please forward the HydroCAD .HCP file to support@hydrocad.net

 

[cassandtim]

Ok, so I'm modeling the two ponds separately using a culvert outlet from Pond 1 to Pond 2. I am also using the DSI method and it appears to be working. My next question is concerning the connecting culvert. The culvert is 24" dia and 300' long. Does the program account for the storage volume in the culvert?

All/any help is greatly appreciated.
Thank you
Tim Smith

 

[psmart]

When you model the pipe as a outlet device, the software evaluates the hydraulic effects on the outflow, but not the storage effects of the pipe.

If you know that the water level is fairly constant along the length of the pipe (as it is likely to be with equalized ponds) then you could include the pipe storage contribution by adding horizontal cylinder storage to one of the ponds.