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Alaska Index of Watershed Integrity
Citation:
Aho, K. AND S. G. Leibowitz. Alaska Index of Watershed Integrity. Multi-agency Watershed Integrity Meeting, Anchorage, AK, November 07, 2017.
Impact/Purpose:
The EPA’s Index of Watershed Integrity (IWI) is used to calculate and visualize the status of natural watershed infrastructure that supports ecological processes (e.g., nutrient cycling) and services provided to society (e.g., subsistence resources). The IWI applied to the conterminous US defined watershed functions specific to running water. However, seasonal ice affects 58% of North America’s streams and rivers. This Alaskan iteration of the IWI will focus on the needs of state partners (e.g., Alaska Department of Environmental Conservation). An Alaska IWI that includes winter functions of aquatic systems could provide insights on seasonal functions, both for Alaska and regions of the CONUS that experience a degree of river ice during the winter. This is done using the 2.2 million stream catchments in the National Hydrography Dataset, information from landscape metrics (e.g., National Land Cover Database), and cold-climate data (e.g., permafrost deepening, glacial melt) from the Alaska Hydrography Database at the University of Alaska Anchorage. This work will also contribute to SSWR 3.01B (Assess, Map, and Predict the Integrity, Resilience, and Recovery Potential of the Nation’s Water Resources) by providing a case study of how the IWI can be used in actual management applications.
Description:
The US Environmental Protection Agency’s (EPA) Index of Watershed Integrity (IWI) is used to calculate and visualize the status of natural watershed infrastructure that supports ecological processes (e.g., nutrient cycling) and services provided to society (e.g., subsistence resources). Specifically, the IWI is based on six functions that watersheds with high integrity are hypothesized to provide: hydrologic regulation, regulation of water chemistry, sediment regulation, hydrologic connectivity, temperature regulation, and habitat provision. To assess the integrity of these six component functions, the IWI considers the occurrence of stressors, or risk factors (e.g., agricultural land cover, road-stream intersections, impervious surfaces). The IWI has been applied to the conterminous US and to the western Balkans. To better support regional decision-making bodies, the EPA is beginning planning for a management-based IWI analysis in Alaska. The geographic scope of such an analysis has not yet been finalized, but could range from a single basin, such as the Matanuska-Susitna River Watershed, to the entire state. In both previous applications, the six watershed functions were defined specific to running water. However, seasonal ice affects 58% of North America’s streams and rivers. An Alaska IWI that includes winter functions of aquatic systems could provide insights on seasonal functions, both for Alaska and regions of the CONUS that experience a degree of river ice during the winter. Our goal for this project is to include in the IWI functions of cold-climate hydrology, to facilitate use of an Alaska IWI by regional management, especially for adaption planning. In order to do so, we will present: 1) an overview of the CONUS IWI and 2) novel cold-climate watershed functions (e.g., climate regulation) and stressors (e.g., biodiversity loss, glacial melt/increased streamflow, greening of the arctic, fire risk).