Sample data from Engineering Database — 375 reference tables, deterministic calculators, and Engineering AI. Sign up free
Stormwater Runoff Coefficients: SCS curve number
cn row crop good A to cn woods good D
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 | return period yr (yr) | standard | surface type | unit |
|---|---|---|---|---|---|---|---|---|
| SCS curve number | cn row crop good A | 67 | Row crops — good condition (contoured and terraced), HSG A | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 Table 9-1; TR-55 Table 2-2c | row crop | dimensionless |
| SCS curve number | cn row crop good B | 78 | Row crops — good condition, HSG B | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | row crop | dimensionless |
| SCS curve number | cn row crop good C | 85 | Row crops — good condition, HSG C | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | row crop | dimensionless |
| SCS curve number | cn row crop good D | 89 | Row crops — good condition, HSG D | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | row crop | dimensionless |
| SCS curve number | cn woods good A | 30 | Woods/forests — good condition (>75% litter), HSG A | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 Table 9-1; TR-55 Table 2-2c | woods | dimensionless |
| SCS curve number | cn woods good B | 55 | Woods/forests — good condition, HSG B | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | woods | dimensionless |
| SCS curve number | cn woods good C | 70 | Woods/forests — good condition, HSG C | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | woods | dimensionless |
| SCS curve number | cn woods good D | 77 | Woods/forests — good condition, HSG D | agriculture | 2 | USDA-NRCS NEH-630 Ch.9 | woods | dimensionless |
What else is in Engineering Database
Iron Engine ↗Engineering AI at ironengine.ai
AI built for engineering. Searches the engineering database, performs calculations, gives source-backed engineering insights.
Get started for free ↗Reference Data375 engineering tablesMaterial properties, pipe and shape dimensions, code tables, and electrical ratings across mechanical, civil, chemical, electrical, materials, and manufacturing engineering.
Browse dataCalculatorsDeterministic engineering calculatorsSizing, checking, and conversion tools that run against the reference tables. Inputs are code-compliant, outputs are traceable to the source standard.
Browse calculators