Projected increases in shoreline erosion and potential flooding risk along China's sandy coasts under a warming climate

Abstract

Shoreline erosion and coastal flooding are two major hazards causing significant losses of life and property in a warming climate. To enhance coastal resilience against climate change, this study offers an integrated assessment of long-term shoreline erosion (the combined shoreline retreats driven by ambient dynamics and sea level rise) and potential flooding risk (PFR, quantified by the annual cumulative exceedance hours of extreme sea levels) along China's sandy beaches. We further examine the concurrent coastal hazard (CCH) of shoreline erosion and PFR, and evaluate the associated exposure of physical assets and population. Our findings suggest that under the high emission scenario SSP5–8.5, China's sandy beaches are projected to experience intensified erosion and elevated PFRs, primarily attributable to rising mean sea levels. Moreover, shoreline erosion is proportionally more prevalent along the southern coasts. Coastlines projected to experience fewer PFR hours tend to exhibit higher severity, and vice versa. As a result, more than 65% of sandy shorelines are threatened by CCH, and over 80% of coastal physical assets and populations along sandy beaches are exposed to CCH. Among the cities in China's Greater Bay Area, Hong Kong and Shenzhen are projected to face the highest levels of exposure for both physical assets and population. This study identifies future hotspots of shoreline erosion and coastal flooding along China's sandy coastlines and provides scientific evidence to support adaptation strategies aimed at mitigating climate-induced coastal hazards.