Stormwater Runoff Coefficients: SCS_curve_number
Rational Method runoff coefficients (C values) by land use/surface type and return period, plus SCS/NRCS curve numbers (CN) by hydrologic soil group (A/B/C/D) and land cover/condition — from ASCE MOP 77, FHWA HEC-22, USDA-NRCS TR-55, and NEH-630
| method type | record id | C max (dimensionless) | description | land use | notes | return period yr (yr) | surface type | unit |
|---|---|---|---|---|---|---|---|---|
| SCS_curve_number | cn_commercial_A | 89 | Commercial and business — 85% impervious, HSG A | commercial | Urban commercial; near-full impervious coverage | 2 | commercial | dimensionless |
| SCS_curve_number | cn_commercial_B | 92 | Commercial and business — 85% impervious, HSG B | commercial | HSG B; urban commercial | 2 | commercial | dimensionless |
| SCS_curve_number | cn_commercial_C | 94 | Commercial and business — 85% impervious, HSG C | commercial | HSG C; urban commercial | 2 | commercial | dimensionless |
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