m
m
Line 11: Line 11:
 
</tr>
 
</tr>
 
<tr>
 
<tr>
<td>Open space (<50% cover)</td>
+
<td>Open space poor condition (<50% cover)</td>
 
<td>68</td>
 
<td>68</td>
 
<td>79</td>
 
<td>79</td>
Line 18: Line 18:
 
</tr>
 
</tr>
 
<tr>
 
<tr>
<td>Open space (50-75% cover)</td>
+
<td>Open space average condition (50-75% cover)</td>
 
<td>49</td>
 
<td>49</td>
 
<td>69</td>
 
<td>69</td>
Line 25: Line 25:
 
</tr>
 
</tr>
 
<tr>
 
<tr>
<td>Open space (<75% cover)</td>
+
<td>Open space good condition (<75% cover)</td>
 
<td>39</td>
 
<td>39</td>
 
<td>61</td>
 
<td>61</td>

Revision as of 20:52, 24 December 2019

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