Curve numbers for urban and agricultural areas

The following table was adapted from USDA Urban Hydrology for Small Watersheds - TR-55.

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

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

The following table was adapted from Hydrologic Analysis and Design (4th Edition) (McCuen).

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.
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

Other sources of information for curve numbers

Other sources of information on runoff coefficients


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This page was last edited on 13 January 2020, at 15:15.

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