Satellite-Based Monitoring of Annual Coastal Reclamation in Shenzhen and Hong Kong since the 21st Century: A Comparative Study

Abstract

To solve the shortage of land resources, many coastal cities have implemented coastal reclamation projects over the past few decades. Coastal reclamation can promote the economic development of coastal cities and improve human well-being in coastal zones. However, it can inevitably cause a series of ecological and environmental issues, such as coastal water pollution, ecosystem destruction, habitat loss, and land subsidence. Shenzhen and Hong Kong are two large neighboring Chinese coastal cities in southern China with different systems. As densely populated and economically developed cities, they face similar land shortage issues. However, recent coastal reclamation changes in Shenzhen and Hong Kong are unclear under different social and political systems. To fill this gap, this study aimed to monitor and compare recent annual coastal reclamation in Shenzhen and Hong Kong with totally different systems using free and open satellite products. Then, to compare the results of coastal reclamation between Shenzhen and Hong Kong. Large-scale coastal reclamation in Shenzhen and Hong Kong from 2000 to 2018 can be observed. The total area of coastal reclamation was 4140.7 hm2, of which the total coastal reclamation area in Shenzhen was 3409.8 hm2 and the total coastal reclamation area in Hong Kong was 730.9 hm2. Coastal reclamation in Shenzhen showed a temporal characteristic of “increasing slightly and then decreasing sharply”. Before and after 2010, the area of accumulated coastal reclamation were 3202.9 hm2 and 206.9 hm2. Comparatively, coastal reclamation in Hong Kong exhibited a temporal characteristic of “first decreasing and then increasing and then decreasing”. In 2002 and 2014, the scale of coastal reclamation was relatively large, with a total area of 501.8 hm2, accounting for 69.19% of its total area of coastal reclamation. The comparison between our produced coastal reclamation and the official area on coastal reclamation exhibited a good agreement based on correlation analysis (r = 0.99) and RMSE (Root Mean Square Error) (0.72). Since the 21st century, Shenzhen and Hong Kong have shown different, even opposite, policies on coastal reclamation. It will be necessary to continuously monitor future coastal reclamation driven by policies for better conducting sustainable coastal development in the Guangdong-Hong Kong-Macao Greater Bay Area.