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Accurate mapping of impervious surface areas is critical to stormwater management because impervious surfaces reduce infiltration of surface water into the soil, thereby increasing runoff which can carry harmful pollutants into streams and lakes. As such, the VT DEC and the City of South Burlington (CSB) sought improved and cost effective means to map impervious surfaces in their respective efforts to model TMDLs for the state's 17 impaired watersheds and develop a tax basis for the City's stormwater utility. To this end, the combination of high spatial resolution (0.6m panchromatic and 2.44m multispectral) QuickBird satellite data and advanced object oriented classification techniques yielded a mapping accuracy of 96.8% within the Potash Brook watershed. Impervious surface area for the 13 impaired watersheds mapped as part of this project ranged from 5.5 - 31.3%. Based on the effectiveness and accuracy of these results, VT DEC and CSB adopted this approach to meet their stormwater objectives. The use of advanced object oriented classification techniques with QuickBird satellite data resulted in consistently reliable, accurate, and cost effective impervious area products. On-going efforts include the incorporation of LIDAR data to differentiate impervious cover types (e.g. buildings, parking lots, roads). |