TR20 VS HEC HMS

[ALBUD1962]

I noticed at least a 20% difference in flows computed using HEC HMS to TR 55 and TR 20 using the SCS method.
Has anyone else had this problem and if so were you able to get the models calibrated more closely?

Thanks

Al

 

[psmart]

You will get a better response if you post in the Storm/Flood engineering forum.

 

[RWF7437]

20% sounds pretty good for hydrology. But do post your question in the storm/flood forum where you'll find lots of well infomed people who may be able to answe your question and explain the differences you're finding.

good luck

 

[blueoak]

Which SCS method?
Are you using the same SCS loss, SCS unit hydrograph, and the same SCS storm? I haven't seen a problem running the same inputs in TR20 or HMS. What are your inputs?

20% sounds okay for different hydrologists who are making their own assumptions. I am a little concerned though that using 2 computer programs for the same methodology and procedures (I assume same model parameters) would give such a different answer.