Spatiotemporal evolution and influencing factors of the coastlines in Hanjiang Delta from 1982 to 2020
In this study,Landsat remote sensing image data and the visual interpretation method were used to investigate the coastline changes of the Hanjiang Delta in the seven periods from 1982 to 2020.The shoreline spatiotemporal evolution of the Hanjiang Delta was identified by analysis of their coastline type structures,lengths and end point rates.Meanwhile the influencing factors of shoreline evolution were discussed.The results show that the coastline lengths of the Hanjiang Delta increased by 51.90 km from 1982 to 2020,due to the growth of artificial coastline and biological coastline.During this time,the Hanjiang Delta has been prograding seaward more than 164.55 m with the average end point rate of 4.35 m/a.The increased coastal zones mainly distributed from Rongjiang Estuary to Laiwu Island and Haimenjiao,while the eroded coasts distributed from Lianyang Estuary to Huangcuocaoxi Estuary.The seaward coastal areas were mainly caused by reclamation and the industrial construction,which also led to some coastal erosion in the form of sandy bars retreat at the same time.The coastline changes of Hanjiang Delta are chiefly controlled by the relative sea level fluctuation,sediment flux of rivers,storm surge activity,hydrodynamic environment and human activities.Among the factors,human activities play a crucial role.