The assessment of coastal vulnerability to erosion is urgently needed due to increasing coastal erosion globally. Based on the coastal characteristics of the Xiamen artificial coastline, which accounts for more than 80% of the coastline in this area, this study provides an integrated approach based on a multi-criteria index. The evaluation index system of the local coastal vulnerability to the erosion of Xiamen includes 12 indexes based on natural (coastal characteristics, coastal forcing), and socio-economic factors (coastal infrastructure, disaster reduction). The spatial differentiation characteristics of the coastal vulnerability to erosion along the Xiamen coast (2018) have been quantitatively assessed with the aid of GIS (Geographic Information System) and RS (Remote Sensing) technology. The results show that the very high vulnerability, high vulnerability, medium vulnerability, low vulnerability and very low vulnerability areas of coastal erosion accounted for 4.6%, 30.5%, 51.6%, 12.5% and 0.8% of the Xiamen coast, respectively. The coastal vulnerability to erosion classes of artificial coasts is significantly higher than those of natural coasts. This difference is mainly controlled by the coastal slope and coastal buffer ability. The results of the evaluation are basically consistent with the present situation. The rationality of the index system and the applicability of the theoretical method are well explained. The evaluation model constructed in this study can be extended to other areas with high ratios of artificial coasts.

Global climate change-induced sea-level rise and storm wave intensification, along with the large population densities and high-intensity human development activities in coastal areas, have caused serious burden and damage to China’s coasts, led to the rapid growth of artificial shorelines development, and formed a “new Great Wall” of reinforced concrete against the laws of nature. After the last ice age, transgression formed the different features of China’s coast. Depending on the types of geological and landform features, coasts are divided into 36 evaluation units, and 10 indicators are selected from natural aspects (including tectonics, geomorphology, sediment, and storms) and aspects of social economy (population, GDP, Gross Domestic Product), and cloud model theory is used to build a coastal erosion vulnerability evaluation index system in China. The results show that high grade (V), high-middle grade (IV), middle grade (III), low-middle grade (II), and low grade (I) coastal erosion vulnerability degrees account for 5.56, 13.89, 41.67, 33.33, and 5.56% of the Chinese coastlines, respectively. The coastal erosion vulnerability of the subsidence zone is significantly higher than that of the uplift zone. Reverse cloud model and analytic hierarchy process calculation show that the main factors that control coastal erosion vulnerability since the transgression after the last ice age are geological structure, topography and lithological features, and in recent years, the decrease in sea sediment loads and increase in reclamation engineering. Mainland China must live with the basic situation of coastal erosion, and this study shows that the index system and method of cloud modeling are suitable for the evaluation of the coastal erosion vulnerability of the Chinese mainland. This study provides a scientific basis for the adaptive management of coastal erosion, coastal disaster assessment and the overall planning of land and sea.

Under the dual effects of global climate change and intensive human development activities, vulnerability to coastal erosion in bay areas is becoming increasingly serious. This study focuses on 15 counties and districts along the coast of the Pearl River Estuary (PRE) Great Bay Area and selects 12 evaluation indices from five perspectives for analysis, including coastal characteristics, hydrodynamic forces, economics, population and coastal reconstruction. The analytic hierarchy process (AHP) method, Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method, independent weight method, Jenks natural breaks method (Jenks), exposure-sensitivity-adaptation (ESA) model and obstacle degree method are used in conjunction with the above indices to construct a coastal erosion vulnerability evaluation system for the PRE. The results show that coastal erosion vulnerability in the PRE is low in the eastern hilly area and high in the central and western delta areas. Coastal characteristics, coastal lowlands and protection capability are the main controlling elements of erosion. The PRE experienced an era of rapid economic development from 1980 to 2010, and coastal erosion vulnerability gradually increased, with a cost of ecological environment destruction. Then, an era of coastal zone ecological restoration supported by policy protection occurred from 2010 to 2020. Compared with three major bay areas with similar developed economies worldwide, the PRE is characterized by comparatively late but rapid economic development. Notably, the development and utilization efficiency of coastal zones is very high, the duration of damage to the ecological environment is short, and the effects of ecological repair and restoration are obvious. The results of this study provide a reference for economic development and ecological restoration in the bay areas of China and provide scientific guidance for coastal zone development, management and planning.

The ecological environment and resource endowment of an island are more vulnerable compared to the mainland, and special assessment and measurement of the ecological suitability for development are significant. Pingtan Island (Fujian, China) was taken as a case study. Changes in ecosystem services value and the profit-and-loss balance between ecological footprint and biocapacity were assessed using land use/cover changes based on remote-sensing images taken in 2009, 2014 and 2017, and the ecological suitability of development was measured. Results show that island development led to a decrease in the ecosystem services value and an increase in ecological footprint and biocapacity. The key ecological factors restricting the scale of island development are topography, vegetation with special functions and freshwater. Biocapacity of islands can increase not only by changing from lower-yield land types to higher-yield construction land types but also by external investment. A new measurement framework was proposed that simply and clearly reveals the ecological suitability of island development and the underlying key constraints.