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Table 5. Impervious Cover (%) for Various Land Uses |
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| Land Use | Density
(dwelling units/acre) |
Source | |||||
| Northern Virginia (NVPDC, 1980)1 | Olympia (COPWD, 1995) | Puget Sound (Aqua Terra, 1994) | NRCS
(USDA, 1986) |
Rouge
River
(Kluitenberg, 1994) |
Model Default2 | ||
| Low Density Residential | <0.5 | 6 | - | 10 | - | 19 | 10 |
| 0.5 | - | - | 10 | 12 | |||
| 1 | 12 | - | 10 | 20 | |||
| Medium Density Residential | 2 | 18 | - | - | 25 | 30 | |
| 3 | 20 | 40 | 40 | 30 | |||
| 4 | 25 | 40 | 40 | 38 | |||
| High Density Residential | 5-7 | 35 | 40 | 40 | - | 38 | 40 |
| Multifamily | Townhouse (>7) | 35-50 | 48 | 60 | 65 | - | 60 |
| Industrial | -- | 60-80 | 86 | 90 | 72 | 76 | 75 |
| Commercial | -- | 90-95 | 86 | 90 | 85 | 56 | 85 |
| Roadway | 80 | ||||||
| 1: NVPDC
data measure effective impervious cover (i.e., rooftops are not included
in residential data)
2: Model default values are approximately equal to the median of Olympia, Puget Sound, NRCS, and Rouge River data, with adjustments made where studies estimate impervious cover for a broad range of densities. |
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