Coastline movement and change along the Bohai Sea from 1987 to 2012

Abstract

Using multitemporal remote sensing data from 1987 to 2012, this study extracted the coastlines along the Bohai Sea and explored the relationship between coastline change and human activity. Our results indicate that the general pattern of coastline change can be divided into two stages: a slow-change stage (1987 to 2002) and a rapid-change stage (2002 to 2012). The total area of the Bohai Sea decreased by 1593.44  km 2 from 1987 to 2012, at an average rate of 63.7km 2 /year . The total length of coastline along the Bohai Sea increased by 633.7 km at an average rate of 25.3  km/year . The length of natural coastline decreased by 836.2 km at an average rate of 33.4  km/year . The length of artificial coastline increased by 1469.9 km, at an average rate of 58.8  km/year. The artificial coastline composed 27.07% and 74.16% of the total coastline lengths in 1987 and 2012, respectively. The natural coastline was the main coastline type in 1987. However, the natural coastline composed only 25.84% of the total coastline in 2012. The maximum progradation in the Bohai Bay occurred in Caofeidian, where the coastline advanced seaward by ∼19630.33  m , at an average rate of 785.23  m/year . The maximum erosion occurred at the head of the abandoned Diaokou promontories, where the coastline retreated landward by ∼4758.01  m , at an average rate of 190.33  m/year . Possible explanations for the coastline changes along the Bohai Sea include natural factors (e.g., riverine sediment supply and hydrodynamic conditions) and human impacts (e.g., reclamation projects), which can be primarily attributed to anthropogenic activities, coastline type, and rapid changes in the Bohai Sea since 2002. The majority of the coastline changes were caused by land reclamation and the construction of embankments. The effects of tides and waves were relatively minimal.