Climate Adaptation Framework for Advancing Community Stormwater Management.

Stormwater runoff has detrimental impacts on urban communities due to historic water management infrastructure being unable to cope with contemporary runoff issues under climate change. Nature-based Solutions (NbS) provide a sustainable alternative for stormwater management while delivering multiple cobenefits for society. However, limited work has quantitatively assessed the financial trade-offs and optimization of NbS configurations. Here, a framework was developed to optimize NbS spatial configurations, achieving legislative targets for nitrogen concentration and runoff reduction under future climate change scenarios. Using Ningbo, China, as a case study, results showed that both runoff reduction and total nitrogen removal decreased by approximately 6% across all climate scenarios. Eight particularly cost-effective schemes were generated through multiobjective optimization based on four preference scenarios for runoff and nitrogen control in high- and low-income communities. Compared to cost-equivalent design alternatives, runoff reduction improved by 0.86-13.9% in runoff-focused schemes, while total nitrogen removal increased by 0.08-8.45% in nitrogen-focused schemes. A 15-year cost-benefit analysis indicated that low-cost NbS yielded higher benefit-to-cost ratios, whereas high-investment schemes, although delivering greater absolute reductions, exhibited lower ratios. The proposed framework provides a robust tool for optimizing NbS in different communities for climate change adaptation.