Tennessee Valley Authority's Watershed-Based Approach to Integrated Pollutant Source Inventory

摘要

Remote sensing and GIS techniques are undoubtedly two of the most powerful tools that can be utilized to facilitate water quality improvement in watersheds. During the past twenty years, the Tennessee Valley Authority has been extensively involved in the identification and abatement of land-based nonpoint source (NPS) environmental problems in the Tennessee River watershed. From our experience, land use and land activity GIS databases, derived from 1:24,000-scale color-infrared aerial photographs, are a cost-effective tool that watershed planners can utilize for developing and implementing NPS pollution corrective actions. The databases aid in: documenting the source, location, and magnitude of all nonpoint pollution problems in the watershed, providing the impetus for getting agencies, industries, interest groups, and landowners together to work toward a common goal, and cost effectively implementing abatement measures through targeting priority watersheds, pollutants, and sites. The comprehensive data details such as eroding road and stream banks, livestock sites, illegal dumps, and suspect septic systems extracted from the stereo photographs provides the first step in determining the cause of a pollution problem in the watershed. Data analysis transforms a dispersed, area-wide concern into a defined, site specific problem by identifying sub-watersheds that are the greatest contributors to the pollution problem, then determining in each priority sub-watershed the specific sites that contribute the greatest pollutant loads. This basic form of geographical targeting is the most efficient and cost-effective approach to watershed improvement. The generated information provides a foundation for fostering environmental awareness, targeting priority impacted watersheds, and identifying abatement measures.