Curve #- Residential Lot Default

[MHMcLeod]

When modeling a subdivision of known lot size (say 1-acre lots/ 20% impervious/ Type C soils) does this CN value of 79 include the paved road frontage associated w/ each lot, or should the roadway be modeled as a separate CN line item in the subcatchment node?

 

[psmart]

Check the percentage of impervious area in your actual lot and see how it compares to the "standard" value. If the values are different, you should probably enter the pervious and impervious areas directly rather than using the pre-averaged value.

This also lets you use the actual CN value for the pervious area, rather than assuming "open space in good condition", as used for the pervious portion of all the "standard" lots.

For additional details, please see the footnotes on the SCS/NRCS curve number table, as printed on page 132 of the HydroCAD-8 Owner's Manual.