Exploring the intersection between coastal flood hazards and socioeconomic exposure: Evidence from China's coastal...

Sea level rise and consequent coastal flooding pose an increasing threat to socioeconomic stability globally, particularly in China's coastal zone (CCZ). However, the long-term spatial correlations between coastal flood hazards (CFH) and socioeconomic exposure (SEE) remain unclear, thereby limiting the accuracy of coastal flood risk assessments. Consequently, novel frameworks are necessary for effective risk management and adaptation strategies. This study employs the Bivariate Local Moran's I approach to analyze the spatiotemporal intersection patterns between CFH and SEE from 2030 to 2100 in the CCZ under various Representative Concentration Pathway-Shared Socioeconomic Pathway (RCP-SSP) scenarios. CFH is evaluated using a depth-affected function, while SEE is quantified through the analytic hierarchy process-entropy weighting (AHP-EW) method. The results indicate that the areas of "High-High" clusters (regions where higher CFH levels are surrounded by higher SEE levels) will increase to 10.26 × 10³ km², 11.86 × 10³ km², and 14.33 × 10³ km² by 2100 under the RCP2.6-SSP1, RCP4.5-SSP2, and RCP8.5-SSP5 scenarios, respectively. These clusters are primarily located in Guangdong, Jiangsu, and Zhejiang, where immediate and robust interventions are essential to protect human and economic assets. By contrast, the areas of "High-Low" clusters (regions where higher CFH levels are surrounded by lower SEE levels) will expand to 17.78 × 10³ km², 16.15 × 10³ km², and 17.31 × 10³ km² by 2100 under the RCP2.6-SSP1, RCP4.5-SSP2, and RCP8.5-SSP5 scenarios, respectively. These clusters are mainly located in Jiangsu, Shandong, and Shanghai, where long-term preventive risk management measures are recommended. By 2100, the GDP and population in the "High-High" clusters are projected to reach $2675.32 billion (13.17 million people), respectively, under the RCP8.5-SSP5 scenario, representing the most severe threat to both economic and population stability. These findings underscore the importance of applying a differentiated risk management approach when formulating coastal flood adaptation policies, as well as providing valuable insights for enhancing the resilience of vulnerable areas in the CCZ to climate change.