Curve numbers for urban and agricultural areas

The following tables were 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.
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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


Curve numbers for antecedent moisture condition II (Source USDA-NRCS).
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Land use description
Hydrologic soil group
A B C D
Meadow - good condition 30 58 72 78
Forest
Poor 45 66 77 83
Fair 36 60 73 79
Good 30 55 70 77
Open space
Poor 68 79 86 89
Fair 49 69 79 84
Good 39 61 74 80
Commercial 85% impervious 89 92 94 95
Industrial 72% impervious 81 88 91 93
Residential
1/8 acre lots (65% impervious) 77 85 90 92
1/4 acre lots (38% impervious) 61 75 83 87
1/2 acre lots (25% impervious) 54 70 80 85
1 acre lots (20% impervious) 51 68 79 84
Impervious areas 98 98 98 98
Roads (including right of way)
Paved 83 89 92 93
Gravel 76 85 89 91
Dirt 72 82 87 89
Row crops
Straight row - good 67 78 85 89
Contoured row - good 65 75 82 86
Pasture - good 39 61 74 80
Open water 99 99 99 99


Runoff coefficients for different soil groups and slopes

The following table was adapted from Hydrologic Analysis and Design (4th Edition) (McCuen, 2017).

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).
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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

This page was last edited on 7 August 2022, at 12:03.