Climate Change Impact on Watershed Sustainability Index Assessment

The Watershed Sustainability Index (WSI) is a widely used parameter that provides an integrated assessment of the baseline state of watershed management, considering hydrology, environment, life, and policy. The impacts of climate change on sustainability are becoming increasingly evident. These impacts are discussed in the 6th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). This study refines the Watershed Sustainability Index (WSI) by embedding climate discontinuities from the IPCC AR6, applying dual climate scenarios (RCP4.5 and RCP8.5), and incorporating comprehensive sensitivity and uncertainty analyses. The approach provides a transferable basis for basin-scale management tools that integrate climate stressors, explore alternative futures, and support adaptive water governance. The impacts of climate change on watershed sustainability have been developed from hydrological, environmental, life, and policy perspectives with an innovative approach. The new WSI assessment methodology is implemented for the Central North Aegean Basin, Türkiye. The WSI was applied to two periods, including five years of baseline condition (2016–2020) and ten years of projected future condition (2021–2030). The future condition was assessed with climate change impacts. The study shows how WSI assessment under climate change considerations may support coordination among all relevant institutions and stakeholders responsible for natural resource management. This approach can be a valuable resource for decision-makers and provide an effective management tool for the basin, considering future conditions.