Stormwater runoff coefficients/curve numbers for different land uses Revision as of 14:55, 13 January 2020 by Mtrojan (talk | contribs)(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff) Stormwater runoff coefficients/curve numbers for different land uses

Curve numbers for urban and agricultural areas

Curve numbers for urban and agricultural areas. Source: [USDA Urban Hydrology for Small Watersheds - TR-55. USDA Urban Hydrology for Small Watersheds - TR-55].
Link to this table

Cover type and hydrologic condition	Soil Group A	Soil Group B	Soil Group C	Soil Group D
Open space poor condition (<50% cover)	68	79	86	89
Open space average condition (50-75% cover)	49	69	79	84
Open space good condition (>75% cover)	39	61	74	80
Impervious surfaces	98	98	98	98
Commercial (85% impervious)	89	92	94	95
Industrial (72% impervious)	81	88	91	93
Residential (65% impervious)	77	85	90	92
Residential (30% impervious)	57	72	81	86
Residential (12% impervious)	46	65	77	82
Pervious, no vegetation (newly graded)	77	86	91	94
Fallow with residue cover	74-76	83-85	88-90	90-93
Row crop, no residue	67-72	78-81	85-88	89-91
Row crop with residue	64-71	75-80	82-87	85-90
Pasture, good condition	39	61	74	80
Pasture, poor condition	68	79	86	89
Meadow	30	58	71	78
Woods, good condition	32	58	72	79
Woods, poor condition	57	73	82	86

Runoff coefficients for different soil groups and slopes

Runoff coefficients for different soil groups and slopes. Coefficients are for recurrence intervals less than 25 years. Source: Hydrologic Analysis and Design (4th Edition) (McCuen, 2017).
Link to this table

Land use	Soil Group A			Soil Group B			Soil Group C			Soil Group D
	0-2%	2-6%	>6%	0-2%	2-6%	>6%	0-2%	2-6%	>6%	0-2%	2-6%	>6%
Residential (65% impervious)	0.25	0.28	0.31	0.27	0.30	0.35	0.30	0.33	0.38	0.33	0.36	0.42
Residential (30% impervious)	0.19	0.23	0.26	0.22	0.26	0.30	0.25	0.29	0.34	0.28	0.32	0.39
Residential (12% impervious)	0.14	0.19	0.22	0.17	0.21	0.26	0.20	0.25	0.31	0.24	0.29	0.35
Commercial	0.71	0.71	0.72	0.71	0.72	0.72	0.72	0.72	0.72	0.72	0.72	0.72
Industrial	0.67	0.68	0.68	0.68	0.68	0.69	0.68	0.69	0.69	0.69	0.69	0.70
Streets	0.70	0.71	0.72	0.71	0.72	0.74	0.72	0.73	0.76	0.73	0.75	0.78
Parking	0.85	0.86	0.87	0.85	0.86	0.87	0.85	0.86	0.87	0.85	0.86	0.87
Open space	0.05	0.10	0.14	0.08	0.13	0.19	0.12	0.17	0.24	0.16	0.21	0.28
Cultivated land	0.08	0.13	0.16	0.11	0.15	0.21	0.14	0.19	0.26	0.18	0.23	0.31
Pasture	0.12	0.20	0.30	0.18	0.28	0.37	0.24	0.34	0.44	0.30	0.40	0.50
Meadow	0.10	0.16	0.25	0.14	0.22	0.30	0.20	0.28	0.36	0.24	0.30	0.40
Forest	0.05	0.08	0.11	0.08	0.11	0.14	0.10	0.13	0.16	0.12	0.16	0.20