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Using Curve Number in SWMM 5.0

Posted by Barbara DuBose on October 27, 2014 at 12:26pm in Hydrology

Hello,

I am new to the site and hoping to get a few questions answered about the newest version of SWMM.  I am currently a student working on a design project and we have choosen SWMM to model stormwater mangement in a cluster resdential development.  I started using HEC HMS and then switched to SWMM a little later and I used the curve number method to generate my runoff depth for pre development and post development conditions.  For some reason the pre development conditions are extremely off, HEC HMS gave me about 0.62 inches of runoff and SWMM gave me about 1.5 inches of runoff (there is no impervious area pre development).  The post development was much closer (only about 0.2 inches off). 

I've checked the curve numbers to make sure they are right and other parameters (area, width, rainfall, etc.) are the same.

 

Has anyone experienced this problem before? Any insight or suggestions would be greatly appreciated!

Thanks!

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Replies

  • walker mendez payehuanca December 22, 2014 at 8:15am

    como usar los numero de curvas en arcgis

  • Robert Dickinson October 27, 2014 at 4:31pm

    The initial abstraction is different in  the CN for SWMM5 - try using IA = 0.2*S and increasing your depression storage in SWMM 5.

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