Global assessment of land subsidence in 48 large coastal cities from a land cover perspective

The assessment of coastal land subsidence is fundamental to the sustainable development in coastal zones. By combining land subsidence and global land cover (GLC) data, we investigate land subsidence in the 48 most populous coastal cities worldwide during 2014-2020 and analyse the underlying causes of land subsidence in these locations. Our results show that, among the 48 global coastal cities, 1) 44 coastal cities show land subsidence (2.70 mm/yr), while only 4 cities show land uplift (0.60 mm/yr); 2) Artificial surfaces contribute to the largest percentage of land subsidence in global coastal cities (56.83%), while cultivated land has the greatest velocity of land subsidence (6.10 mm/yr); 3) Artificial surfaces correspond to the largest percentage of land subsidence in both cities from developing countries/regions (51.58%) and developed countries/regions (75.09%), while cities from developed countries/regions exhibit a larger percentage of land subsidence covered by cultivated land (28.96%, with the velocity of 6.29 mm/yr) compared with cities from developing countries/regions (11.75%, with the velocity of 4.40 mm/yr). Results show that coastal land subsidence has been widely observed across the globe with a large spatial heterogeneity. Coastal land subsidence can be caused by various factors, especially for impervious surfaces and cultivated land.