Curve number equivalences between HEC-1 and Hydrocad

[JALeng]

I tried to make similar model to analyst a watershed using two different software (HEC-HMS and Hydrocad) to verify the results. In most case the result are not equivalents. I can use an equivalent curve number on Hydrocad to obtain similar results?

 

[psmart]

To get the same runoff, make sure both programs are using the same runoff procedure (presumably the SCS Unit Hydrograph method) and verify that ALL of these input parameters are the same:

Curve Number
Time of Concentration
Rainfall distribution (Type II, III, etc)
Rainfall duration (e.g. 24-hours)
Rainfall depth
Unit Hydrograph (check the peak factor)

There are other possible reasons for a difference, but these are the primary suspects.

Peter Smart
HydroCAD Software

http://www.hydrocad.net