Adapting the Index of Watershed Integrity for Watershed Managers in the Western Balkans Region

Sustainable development is essential to maintain a watershed’s capacity to support 16 ecological processes and functions. The Regional Environmental Center for Central and Eastern 17 Europe and the U.S. Environmental Protection Agency (EPA) adapted the U.S. EPA’s Index of 18 Watershed Integrity (IWI) to aid the sustainable development of the western Balkans’ 19 transboundary river and lake basins. The IWI evaluates six watershed functions (hydrologic 20 regulation, regulation of water chemistry, sediment regulation, hydrologic connectivity, 21 temperature regulation, and habitat provision) based on a suite of anthropogenic stressors (e.g., 22 impervious surfaces, reservoirs). A key feature of the IWI is that it provides a cumulative value 23 of all upstream activities for each location in the river network. IWI scores calculated for the 24 1084 catchments of the study area indicated high integrity in the Alpine geographic region (mean 25 = 0.55, standard deviation (SD) = 0.11) and intermediate to low integrity within the 26 Mediterranean (mean = 0.49, SD = 0.12) and Continental (mean = 0.40, SD = 0.10) geographic 27 regions. Comparing the western Balkans IWI results to site response data from a regional 28 chemical assessment (Modelling Nutrient Emissions in River System) and a regional physical 29 assessment (Hydromorphological Assessment), we found that the IWI results had greater 30 correlation (r = 0.63) with the basins’ chemical properties. The IWI results are presented 31 hierarchically (stressor, functional component, IWI) and alongside their corresponding 32 management entities (local, national, international) and aquatic scales (stream, catchment, 33 watershed). The IWI can be deconstructed to its constituent functional components by 34 management entities to screen for stressors as well as preserve ecosystem services at the 35 corresponding aquatic scales. We present examples of these applications and suggestions for 36 improving the assessment.

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., local, national, international), and IWI metrics (e.g., stressor, functional component, and ICI and 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.

Citation

Aho, Kelsey B, Joseph E Flotemersch, Scott G Leibowitz, Zachary C Johnson, Marc H Weber, AND Ryan A Hill. Adapting the Index of Watershed Integrity for Watershed Managers in the Western Balkans Region. Springer-Verlag, New York, NY, 65(5):602-617, (2020). [DOI: 10.1007/s00267-020-01280-x]

DOI: Adapting the Index of Watershed Integrity for Watershed Managers in the Western Balkans Region