I am trying to calculate Peak flow rate for same watershed with two different software's both calculate based on SCS method. I used Tr-55 and Pondpack model for same case. I also assigned same Tc and same landcover area with soil type. But, I got different results from two software's, where it seems they are nearly close but not too close.
Now my problem is which one is right? Is there any reason behind that ?
Please find the following attachments. And I double checked that I used same value for both case.
The SCS Unit Hydrograph method in PondPack uses a hybrid of the TR-20 and HEC-1 approaches. TR-20 is generally considered to be more accurate than the old manual TR-55 method. You can change the Options in PondPack to use TR-20 or HEC-1 instead of the hybrid approach default (Tools>Options>Project), and you can adjust the catchment "calculation increment", but you still may not exactly match the TR-55 results since the calculation method is different. You may want to simply consider the PondPack results to be more accurate.
See more in the following article from our Wiki: SCS Unit Hydrograph method - TR-20 or TR-55?
Jesse DringoliTechnical Support Manager, OpenFlows ProductsBentley Communities Site AdministratorBentley Systems, Inc.
Answer Verified By: Sushma Choure
Thank you so much sir.As always great help from Bentley.
Have a wonderful weekend.