Ecosystem-based adaptation strategies to multi-hazard risk reduction and policy implications in the Pearl River and Yangtze River deltas, China

There is growing interest in ecosystem-based adaptation (EbA) as an approach for climate change adaptation, disaster risk reduction (DRR), and the achievement of sustainable development goals. In this study, EbA is synonymous with ecosystem-based DRR for climate-related risk reduction and aligns with nature-based solutions designed for climate change adaptation. Its practice emphasizes the co-benefits of ecosystem protection and restoration, such as reduced exposure to various natural hazards, reduced vulnerability, and enhanced livelihood resilience. Establishing localized EbA initiatives to effectively respond to climate change requires an integrated assessment encompassing the understanding of dynamics of the local social-ecological system. Here, we use two risk assessment frameworks that comprehensively consider social and ecological dimensions of risk. The Global Delta Risk Index (GDRI) addresses social susceptibility, coping and adaptive capacity, ecosystem susceptibility and ecosystem robustness as core components of vulnerability. The DELTA-ES-SES framework, which is derived from the GDRI, additionally considers the intensity of multiple hazards and the importance of ecosystem services in reducing disaster risks. Using both frameworks, we (1) map high disaster risk areas in the Pearl River and Yangtze River deltas, (2) analyse regional differences in vulnerability and risk levels caused by different risk components within deltas, (3) identify key ecosystem services that relate to disaster risk, (4) outline EbA designs applicable to priority regions, and (5) provide policy suggestions for future plans. In doing so, we highlight the linkages between ecosystem services, current EbA practices, and global/national policies to promote the success of EbA in regions exposed to natural hazards. • Two risk assessment frameworks were applied to the Pearl and Yangtze River deltas (PRD&YRD) • Risks are higher in the coastal southwestern PRD, northeastern and southeastern YRD • Ecological vulnerability greatly affects overall vulnerability and risk levels • An ecosystem service-based adaptation framework is presented to inform EbA strategies • Refining ecosystem-based adaptation emphasises design for specific ecosystem types