Trying to remake an old HEC 2 print out in hec ras

[Anonymous]

Hello,

I am currently on a project where I have been given old cross section print outs as well as existing and developed water surface profile elevations. However I was never given the HEC-2 model to import into HEC-RAS. I have hand imported and remade the cross sections from all of the HEC-2 cross sections into HEC-RAS as well as the 4 cross sections where there was a span bridge which I also created in the HEC-RAS roadway/bridge. When I finished and ran the model I am still a half a foot to a foot off in elevations especially the last cross section. The major question is when trying to recreate a HEC-2 model in HEC-RAS will the water surface elevations not match up due to the fact I didn’t model them into HEC-2. I was also wondering the effect the HEC RAS modeling of the bridge would effect the overall water surface elevations compared to HEC-2 modeling of a bridge.

[Vince Moody]

I’ve been there, and it was a pain to fat-finger all that old HEC-2 data into the program. I had a copy of a copy of the original data and it was far from clear what was a 4 and what was a 9 sometimes. All that aside, there are some differences between HEC-2 and HEC-RAS that might be affecting your results, especially around bridges. The good folks at HEC were well aware of this when they wrote the program, so they provided ample documentation for the end user in the User’s Manual and Hydraulic Reference Manual. Check out the discussion beginning on page 3-19 of the User’s Manual, and Appendix C of the Hydraulic Reference Manual. I would make sure to do a detailed QC of the data you hand-typed into RAS, as it’s a likely source of potential differences between the two programs. Once you’re confident in the fidelity of your data, the User’s Manual has a few additional things you should keep in mind when trying to reproduce results. Good luck!

[Author]

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