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AN ARCGIS TOOL FOR CREATING POPULATIONS OF WATERSHEDS
Citation:
Chaloud, D J., D W. Ebert, T G. Wade, AND A M. Pitchford. AN ARCGIS TOOL FOR CREATING POPULATIONS OF WATERSHEDS. Presented at American Water Resources Association, 2004 Spring Specialty Conference Geographic Information Systems (GIS) and Water Resources lll, Nashville, TN, May 17-19, 2004.
Impact/Purpose:
The overarching objective is to develop and test landscape indicator statistical models for condition of streams and aquatic biota in relation to pesticides, nutrients, sediments and toxic substances, nationwide. The indicator models will serve as tools for managers who want consistent methods to compare potential impacts on streams within a biophysical region for differing landscape patterns. To accomplish this objective, several sub objectives will be important:
Develop landscape indicator statistical models of stream vulnerability for selected regions of the U.S., beginning with the Mid-Atlantic Coastal Streams; studies in the Midwest, California, and the Southeast will follow.
Demonstrate the application of the landscape indicator models for the ranking of watersheds, the identification of "hot spots," and the evaluation of management options using projected future scenarios of land use for the study areas selected above.
Develop statistical distributions for physical characteristics of small water bodies for use in OPP modeling.
Leverage resources for this research by incorporating existing data into the model development process, and by sharing field study costs with other projects in the same geographic areas.
This task represents a topic area within the Landscape Sciences research program which is described in A National Assessment of Landscape Change and Impacts to Aquatic Resources. A 10-Year Research Strategy for the Landscape Sciences Program, EPA/600/R-00/001. It also supports the Regional Vulnerability Assessment (ReVA) Program.
Besides being responsive to the Office of Pesticide Programs, this research directly supports long-term goals established in ORD's multi-year research plans related to GPRA Goal 2 (Water Quality) and GPRA Goal 8.1.1 (Sound Science/Ecological Research). Relative to the GPRA Goal 2 multi-year plan, this research will "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors" and "provide the tools to restore and protect aquatic ecosystems and to forecast the ecological, economic, and human health outcomes of alternative solutions" (Long Term Research Goals 2 and 3). Relative to the Goal 8 multi-year plan, this research will develop and demonstrate methods to provide states, tribes, and federal, state and local managers with abilities to: (1) assess the condition of waterbodies in a scientifically-defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales; (2) diagnose cause and forecast future condition in a scientifically defensible fashion to more effectively protect and restore valued ecosystems; and (3) assess current and future ecological conditions, probable causes of impairments, and management alternatives.
Description:
For the Landscape Investigations for Pesticides Study in the Midwest, the goal is to sample a representative subset of watersheds selected statistically from a target population of watersheds within the glaciated corn belt. This area stretches from Ohio to Iowa and includes parts of Michigan, Wisconsin and Minnesota. Although readily available watershed delineations such as the National Resource Conservation Service's 12- and 14-digit hydrologic unit code (HUC) delineations provide consistently-determined watersheds within states, the level of detail varies among the states in the Midwest. To provide a consistently determined target population of watersheds across the entire area, we developed ArcGISTM arc macro language (AML) computer code that allows many options for generating watersheds. After examining the characteristics of watersheds derived from the different options, we generated watersheds associated with third order streams for the forty-two 4-digit HUCs comprising the study area. The approach involved using National Elevation Dataset (NED) data with partial burn-in of streams from the National Hydrographic Data set, and no walls. Details of this approach and the resulting watersheds will be described.