Investigating spatiotemporal coastline changes and impacts on coastal zone management: A case study in Pearl River Estuary and Hong Kong's coast

Changes in coastlines and coastal zones reflect human activities and global changes. Using Landsat imagery from 1998 to 2021, the temporal and spatial variation characteristics of coastlines and the coastal zone land-use/land-cover (LULC) in Pearl River Estuary and Hong Kong's coast were studied during this period, followed by an analysis of how human activity affects coastline changes, in an attempt to provide a basis for decision-making in coastal zone management. Our results show that the coastline expanded outward, demonstrating an obvious trend that featured increasing length. The coastal zone was observed to primarily comprise construction land and woodland, of which the construction land displayed significant growth in contrast to the woodland's decreasing trend, indicating that the coastline was changing from natural to artificial in character. Human activity in the coastal zone had a significantly positive impact on the coastline length. While the amount of coastline in all sub-regions of the study has increased overall, the coastline length in Guangzhou-Dongguan, in particular, exhibited the greatest growth. During analysis, a positive correlation emerged between coastline length and fractal dimension, in particular, the correlation between Shenzhen coastline length and fractal dimension demonstrated the highest level among the four sub-regions studied. With the exception of Hong Kong, construction land increased significantly in all coastal areas and encroached on other types of land, such as cultivated land and woodland. In addition, except for Hong Kong, human disturbance in the coastal zone increased. Among all study areas, Shenzhen revealed a significant increase in human disturbance over the period of interest, exhibiting the highest level of this factor among the sub-regions of the study. These findings could potentially facilitate effective coastal zone management to achieve sustainable development in coastal areas.