Floodway calculation at ponded area

[Anonymous]

Hi,

I am trying to model a floodway but am having trouble. At the downstream end of the study, the stream flows through a railroad culvert, which backs up the flood. The flood behaves as a level pool. HEC-RAS is giving me unrealistic answers in the Method 4 encroachment run. For example, it always exceeds the target increase no matter what I change it to, it calculates encroachment stations far outside of the limits of my cross sections, and it insists on vertically extending the cross section even though my cross sections have enough topographic relief to contain the flood. I don’t know how to resolve this issue. Any suggestions?

Thanks,
Jack

[Lonnie A]

Sounds like a problem with the culvert. Does your unencroached profile look right? My first guess would be you need to add or adjust ineffective flow stations up and downstream?

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