Dynamic changes of the Huizhou Coastline in nearly 50 years based on Landsat images and DSAS
Dynamic changes of the coastline reflect the transgression-regression process of the sea-land interaction,which is of great significance to the environmental protection and development planning of coastal areas.On the basis of six periods of Landsat satellite images from 1973 to 2019,this paper obtained coastline data of each period and calculated the changes in their length and type by means of human-machine interactive interpretation.Detailed analysis in terms of Net Shoreline Movement(NSM),End Point Rate(EPR),and Linear Regression Rate(LRR)in the Digital Shoreline Analysis System(DSAS)were conducted to explore the potential driving factors regarding the dynamic changes of the coastline.Results show that from 1973 to 2019,the total length of the Huizhou coastline increased from 224,565 m to 249,656 m,with an average NSM of 185.46 m and an average EPR of 4.04 m/a.The coastline was mainly characterized by erosion from 1973 to 1984 and showed an overall expansion trend afterwards.The expansion amplitude of the coastline exceeded the highest during 1984-1993,with the NSM reaching 100.2 m.In addition,the artificial coastline,which is mainly distributed in Daya Bay Petrochemical Zone,northern Fanhe Bay reclamation and aquaculture Section,Huizhou Port,western Kaozhou Bay reclamation and aquaculture section,and the vicinity of Huangbu Town section,showed the most remarkable change(8.27％—57.45％)among the different coastline types.The main reasons of coastline change include the development of a coastal aquaculture;the construction of ports,industrial areas,and coastal tourist areas;and the expansion of construction land due to population growth and economic development.Some coastline segments,such as the core area of Xunliao Bay and the east and west flanks of Shuangyue Bay,remained stable during the whole period.We conclude that human impact was the main driving factor and that natural factors have little influence in the coastline change during past nearly 50 years.Compared with other coastal zones in mainland China,the rate of change in Huizhou is less remarkable.Judging by the EPR(2.51％)from 2013 to 2019,the change of coastline in Huizhou remained stable.Thus,we estimate that there will be no significant expansion toward the sea in the future.
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