WIN TR-55 and HEC-HMS

[ralaimo]

I am reviewing a 3 acre project where the design engineer has used WIN TR-55 to determine the pre-development peak flows, but uses HEC-HMS to route the post-development flows. The report contains hardly any input or output data for the routing calculations, so he will have to provide additional information. I have never used HEC-HMS and have never used WIN TR-55 to doing routing. I question the use of two different models (even if both are based on TR-20?) for comparing pre and post developed flows. Thoughts?

 

[pinkpig]

They will generate small difference suppose you use same CN, TC, rainfall,...
but I don't see why they did not use HEC-HMS for pre if the purpose is to compare the two conditions.