Fig 1.
Location map of the study area.
It includes the Liaodong Bay, Bohai Bay and Laizhou Bay. The region is located in Liaoning, Tianjin, and Hebei and Shandong. The coastal area of the Bohai Sea has many ports and has been experiencing rapid industrialization and urbanization.
Table 1.
Path/Row and date of Landsat remote sensing images used in the study.
Fig 2.
Typical landscape in the reclaimed area in the Bohai Sea.
In 2009, a coastal survey was conducted and identified different reclamation process. (A) In the beginning of reclamation; (B) Port land use; (C) Storage yard; (D) Newly enclosing sea; (E) Unused built-up; (F) Vegetation within ports.
Fig 3.
Changes of coastline length of natural, semi-natural, artificial types, reclamation area in the reclaimed area in 2002–2018 in the Bohai Sea.
From the perspective of spatial distribution, the reclaimed areas in the main ports were more than 300 km2. The natural coastline length in Tianjin decreased sharply and artificial coastline length increased evidently.
Table 2.
Changes of different coastlines length and reclamation areas in the Bohai Sea during 2002–2018.
Table 3.
Changes of port reclamation area, port built-up percentage, throughput, and land use efficiency during 2002–2018 in the Bohai Sea.
Fig 4.
Land use types within the reclaimed area and throughput changes of port clusters in the Bohai Sea.
The land use types were classified into built-up, forest and grassland, newly enclosing sea, and other land use types. The proportion of built-up in all ports showed obvious differences.
Table 4.
Areas of different land use types within the port boundary in the Bohai Sea in 2018 (Unit: Km2).
Fig 5.
Future trends of reclamation intensity of port clusters in the Bohai Sea.
The port reclamation will continue to expand. However, different ports have different reclamation intensity. For example, the planned reclamation area of Binzhou, Tangshan, and Huanghua ports is relatively larger, however, the number in Panjin and Dongying port is less than 10 km2.
Table 5.
Planned area and intensity of port clusters reclamation in the Bohai Sea in 2018–2030.
Table 6.
The policy changes of the CLR in China since 1970s.