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A Modeling Approach for Estimating Watershed Impervious Surface Area from National Land Cover Data 92

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Abstract:We used National Land Cover Data 92 (NLCD92), vector impervious surface data, and raster GIS overlay methods to derive impervious surface coefficients per NLCD92 class in portions of the Nfid-Atlantic physiographic region. The methods involve a vector to raster conversion of the impervious surface data and subsequent overlay comparison with the raster NLCD92 data to derive a per-pixel amount of impervious surface for each NLCD92 cell. Sample areas for the study were twenty-seven small sub-watersheds ranging in size from three km2 to 100 km2. A three-category rural-to-urban gradient study design was utilized due to the changing sub-pixel relationship of impervious surfaces within developed/non-developed areas. We used ten "rural" (< 9 percent impervious surface) sub-watersheds, seven "intermediate" (9-18 percent impervious surface) sub-watersheds and ten "dense suburban" (18-35 percent impervious surface) sub-watersheds to produce three separate coefficient models per NLCD92 class. Results show distinct per-class coefficient groupings based on the rural-to-urban gradient with impervious surface coefficients being directly related to the increasing level of impervious surface percent in the watershed. To determine gradient type for any given watershed, we developed an a priori indicator based on the percentage of NLCD92 developed pixels (21, 22, and 23) within a watershed. The subsequent regression formula, y--0.3966(x) + 2.4977, provided an approximation of watershed impervious surface percent which then allowed one of the three coefficient models to be applied. Results from the application of coefficients to all 27 watersheds shows a relative accuracy for the impervious surface prediction of 85% and a mean absolute impervious surface percent error of 1.4% & 0.5% at both the Anderson Level I coefficients and the Anderson Level 2 coefficients.
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Citation:Jennings, D. B., S. T. Jarnagin, and D. W. Ebert. A Modeling Approach for Estimating Watershed Impervious Surface Area from National Land Cover Data 92. PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING 70(11):1295-1307, (2004).
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Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
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Division: Environmental Sciences Division
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Branch: Landscape Ecology Branch
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Product Type: Journal
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Published: 11/09/2004
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Related Entries:
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Bullet Item Landscape Indicators of Surface Water Conditions
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