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SCREENING TO IDENTIFY AND PREVENT URBAN STORM WATER PROBLEMS: ESTIMATING IMPERVIOUS AREA ACCURATELY AND CHEAPLY
Citation:
Bird, S L., J. Harrison, AND L R. Exum. SCREENING TO IDENTIFY AND PREVENT URBAN STORM WATER PROBLEMS: ESTIMATING IMPERVIOUS AREA ACCURATELY AND CHEAPLY. Presented at National Water Quality Monitoring Conference, Madison, WI, May 20-23, 2002.
Impact/Purpose:
This research project sets out to design and conduct an assessment of the long-term ecological consequences of alternative management choices. As the first project to be done at this scale using predictive ecological endpoints, we will seek to identify the appropriate components of such an analysis. We will use experience gained in the conduct of this BASE analysis to identify key research and data needs for address, to estimate timing, resource needs, etc., for future analyses. We will extend this analysis beyond previous and ongoing studies in two ways: by incorporating biological endpoints, primarily properties of fish communities, and by introducing the concept of sustainability of ecological state under future scenarios contrasted with the present state of those same ecological resources. Requirements that are identified during the course of this study will permit the recommendation of specific capabilities that should be incorporated in a general modeling system currently under development to support BASE and other environmental assessments. Finally, the analysis is intended to be of value for establishing environmental management choices that will be beneficial and those that would be detrimental to the sustainability of ecological resources of the Albemarle-Pamlico Basin.
Description:
Complete identification and eventual prevention of urban/suburban water quality problems pose significant monitoring challenges. Uncontrolled growth of impervious surfaces (roads, buildings and parking) causes detrimental hydrologic changes, stream channel erosion, habitat degradation and severe impairment of aquatic life. Aerial photography (digital orthophoto quarter quadrangles - DOQQ's), sampled statistically using desktop GIS tools, were used to evaluate impervious area estimates based on available landscape data including categorized land cover data (National Land Cover Data - NLCD), block level census data, and road networks. The wide area estimation techniques provided: 1) cheap estimates of impervious cover with known accuracy at the watershed and sub-watershed scales, 2) a comprehensive regional ranking of waters likely impaired by urban storm water, and 3) characterization of imperviousness changes over time. These screening results can guide in-situ monitoring to confirm problems, aid 303(d) listing and development, provide sound information to energize local decision makers, and promote protection and restoration of urban streams.