Since I've began using Civil 3D 2019 about a year ago, I've noticed that the Hydroflow Hydrographs (HH) program contained within provides bogus results when routing a hydrograph through a detention pond. I have been designing detention ponds for several years, so I have a pretty good feel for the results I should be getting. I don't see a problem with the peak flow values for a sub-basin that are computed from the generation of the hydrographs themselves; the problems lies somewhere within the routing process through the detention pond.

I have a older laptop with Land Desktop 2009 and a stand alone version of HH 2009 loaded on it, and I use it to for storm water detention design and analyses. If I didn't have it, I would be stuck.

Has anyone encountered similar issues with HH in Civil 3D that can help me with a fix to the issue? Many thanks in advance.

Shannon Wells