Evaluating flood risk management performance under climate change based on nature-based solutions - empirical evidence from Taihu Lake Basin.

Identifying a flood risk management (FRM) performance evaluation method that aligns with the sustainable development goals of the natural-social complex ecosystem is essential for effective and timely responses to flood risks. Using the Taihu Lake Basin (TLB) as a case study, this research systematically examines the evolving needs of FRM under climate change and proposes a performance evaluation method based on Nature-based Solutions (NbS). The method covers multiple dimensions including flood resources, socio-economic, and environmental factors. Principal component analysis (PCA) is employed to assess changes in the FRM level in TLB from 2010 to 2020. The key findings are as follows: First, FRM in TLB demonstrated a nonlinear upward trend, with the comprehensive FRM score increasing from 1.07 to 9.01, and marked differences in performance observed before and after 2016. Second, from 2010 to 2016, the annual growth rate of the comprehensive score reached 30.27%. Lower scores in ecological protection and agricultural flood control reveal an imbalanced focus on infrastructure. Third, from 2016 to 2020, after the introduction of NbS into basin-level FRM, the components related to natural ecology, ecological environment, and agricultural production resilience recorded annual growth rates of 45.34%, 36.93%, and 179.80%, respectively. These findings underscore the importance of incorporating NbS into FRM and adapting policies in response to climate-induced flood risks. This study offers a structured approach to FRM, contributes to sustainable development planning in TLB, and serves as a reference for similar regions.