Assessment of coastal erosion vulnerability and socio-economic impact along the Yangtze River Delta

Vulnerability assessment is critical for management of hazards in coastal area. However, research on erosion vulnerability assessment in delta region is still very limited. In this paper, we assessed the erosion vulnerability of 49 towns along the coast of the Yangtze River Delta by combining five physical (i.e., mean tidal range, mean wave height, suspended sediment concentration, tidal flat width, and coastal slope) and three social (i.e., embankment height, GDP per unit area, and fiscal revenue) indicators using the percentile ranking method. Population density and land use were analyzed to reveal the potential socio-economic impact of erosion. The assessment result of physical vulnerability is validated by comparison with the bathymetric change between 1980s and 2010s and previous assessment studies using different indicators and aggregation methods. Our results show that areas categorized as very high, high, moderate, low, and very low vulnerability account for 13%, 22%, 39%, 24% and 2% of the coastal towns, respectively. Vulnerable towns with very high and high socio-economic impacts are located along the coastline with narrow tidal flat and lower social coping capacities. The large variability in the physical vulnerability assessment result demonstrates that fine scale study at town level is extreme important, considering the spatial heterogeneity in geomorphological process within the fluival-tidal delta. Our method of erosion vulnerability assessment has potential use in deltaic environments elsewhere.