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Applying the Index of Watershed Integrity to the Western Balkan Region
Citation:
Aho, K.B., J. Flotemersch, Z. Johnson, M. Weber, R. Hill, AND S.G. Leibowitz. Applying the Index of Watershed Integrity to the Western Balkan Region. 10th Eastern European Young Water Professionals Conference, Zagreb, N/A, CROATIA, May 07 - 12, 2018.
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 U.S. IWI accumulated 19 variables (e.g., road-stream crossings) of the 2.2 million watersheds in the National Hydrography Dataset. As a living laboratory, the Western Balkan IWI (W.B. IWI) pilots the use of local stressors and shares lessons learned. The W.B. IWI addresses 1084 watersheds, or 0.05 percentage of the U.S. analysis. This regional adaptation focuses on management applications by local partners (e.g., International Sava River Basin Commission). This is done using a hierarchical matrix of geomorphic features (e.g., stream, catchment, watershed), management entities (e.g., town, country, international), and IWI metrics (e.g., stressors, functional components, IWI). 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:
In 2014, the western Balkans’ heaviest recorded rains triggered extensive flooding affecting approximately 29,600 km2, or the equivalent of 75% of the study area. Rapid urbanization and the increasing regularity of late-summer droughts in the region likely exacerbated these floods. Study Area In response, the Regional Environmental Center (REC) for Central and Eastern Europe and the U.S. Environmental Protection Agency (US EPA) adapted the US EPA’s Index for Watershed Integrity (U.S. IWI; Flotemersch et al. 2016) for application to the Drin River, Drina River, Skadar Lake and Prespa Lake watersheds (Figure 1). The U.S. IWI evaluates six watershed functions (hydrologic regulation, regulation of water chemistry, sediment regulation, hydrologic connectivity, temperature regulation, habitat provision) based on a suite of 19 stressor variables (e.g., road-stream intersections, atmospheric deposition, impervious surfaces, fertilizer application) (Thornbrugh et al., 2018). For the western Balkan IWI (W.B. IWI), individual stressors required adaptation to account for the region’s topography, land use trends, and data availability. Stressor Accumulation A key feature of the Index of Watershed Integrity is that scores at any location in a watershed are a product of all cumulative upstream activities. Once mapped, results can be used to visualize the connections between upstream and downstream stressors and thereby support cooperative management across these transboundary watersheds. W.B. IWI scores calculated for the 1084 catchments of the study area indicate high integrity in the Alpine region (central to the study area), and intermediate and low integrity within the Mediterranean and Continental regions (SW and NE of the study area). Further, the W.B. IWI accounts for 64% of the variation in the nitrogen and phosphorus model- “Modelling Nutrient Emissions in River Systems”. Management Applications Regulation services, such as river flood mitigation, are most often managed at the international scale while cultural services, such as recreation, are often managed at the regional or local scale. We present the W.B. IWI values at the Watershed (International or the Index of Watershed Integrity), Catchment (Regional or Functional Component), and Stream (Local or Stressor) scales (Figure 2). Such information provides local, regional and international entities with the ability to deconstruct the W.B. IWI to identify driving stressors and increase their effectiveness managing transboundary watersheds.