Changes in the Coastline and a Reduction in Area of the Bohai Sea from 2000 to 2016

Intense development has been occurring along the shores of the Bohai Sea that threatens to increase local levels of pollution. A need existed to extract the coastline data of the Bohai Sea from remote sensing images to document changes in the coastline. Landsat imagery from 2000 and 2016 was used to analyze the temporal-spatial changes along this coastline. The results showed that the total length of the coastline increased by 1 111.5 km (40%) during this period. In addition, development has caused the conversion of natural coastline to man-made coastline, and the length of total man-made coastline increased by 1 532.9 km. Among three bays (Bohai, Liaodong, and Laizhou bay), Bohai Bay experienced the greatest increase in the coastline. The lengths of total coastline and the related man-made coastline both doubled a change that also involved a drastic reduction in sea area. The total area of the Bohai Sea declined by 2 360 km2 from 2000 to 2016 to 75 200 km2. Bohai and Laizhou bays both experienced a nearly 10% reduction in their respective original areas. Specifically, Bohai Bay lost 1 165 km2 of area, accounting for half of the total reduction in the area of the Bohai Sea during this time period. More than 95% of lost sea area was converted to enclosures for aquaculture or used for the construction of harbors, docks, and industrial parks. The reduction of sea area and changes in the hydrodynamic environment will affect the environmental carrying capacity of the Bohai Sea.