Remote Sensing Study On Temporal And Spatial Evolution Of Coastal Banks In Jiangsu Province

Coastline monitoring is the basic of understanding the coastal changes. Jiangsu Province as a major economic and coastal province, in recent years, the intensity of coastal development is increasing. The dynamic monitoring of the changes of Jiangsu Province's coastline has become an important task for the coastal exploitation and management. For Jiangsu strong tidal coast which is mainly composed of muddy silt,the changes of erosion and deposition is complicated and field survey of coastline is much more difficult. Furthermore, the update of coastline data can not keep up with the actual demand of ocean management. Accordingly, this paper uses remote sensing technology and puts forward the concept of remote-sensing coastline. This paper extracts remote-sensing coastlines, artificial shorelines, mean low water springs, slope and range of intertidal zone of Jiangsu continental coast from 1984 to 2016 by multi-source remote sensing images. The coastline changes of Jiangsu continental coast are monitored in a long time scale by 1984.1992,2000,2008 and 2016. As well as the coastline changes of the central coast of Jiangsu are monitored in a short time scale from 2010 to 2016 year by year. The main research contents and conclusions are summarized as follows:(1) Calculation of mean high water springs based on improved water-line method.Due to the remote-sensing coastline are combined of the mean high water springs and other stable shorelines. Firstly, this paper predicts sea levels by tidal harmonic calculation with tidal date from several tide sites. Secondly, according to the predicted sea levels of imaging time, the sea levels of waterlines are corrected. Thirdly, the slope of sections of waterlines are corrected based on the data of predicted sea levels and measured slopes. Finally, the mean high water springs and mean low water springs can be calculated.(2) Remote-sensing coastline monitoring results of Jiangsu continental coast shows that a large number of natural shorelines is replaced by the artificial shorelines with the large-scale development of coastal areas. The coastlines move forward to sea,except the Abandoned Yellow River Delta area where exists erosions of shorelines. The maximum distance that coastlines advancing to the sea area are caused by human activities. Moreover,the resources of intertidal zone are decreasing and the intertidal slopes between Liezi estuary to Liangduo estuary are steepening.(3) The erosion and deposition of coastlines. According to the monitoring results of remote-sensing coastlines, the main erosive coastal segments of Jiangsu are Xiuzhen estuary to Longwang estuary coast, the Abandoned Yellow River Delta area and Dongzao harbor to Haozhi harbor coast. The main silt-up coast is the north wing area of radial sand ridges. But the other silt-up coasts are almost replaced by artificial shorelines. Furthermore, the coastlines' advance speed of natural coasts are directly effected by the artificial construction activities inside. According to the monitoring results of mean low water springs,the erosive range of subtidal zone is relatively larger.The range is mainly included Shaoxiang estuary to Liangduo estuary coast which is the whole Abandoned Yellow River Delta coast and the north wing area of radial sand ridges.(4) According to the monitoring results of 1984-1992, it can be concluded that Sheyang estuary should be the dividing point of the middle Jiangsu from the erosion in north to the deposition in south. However, from the monitoring results of 2010-2016 year by year, it is found that erosive phenomenon has extended southward. To the Xinyang harbor to Doulong harbor coast, the erosion and deposition is alternate distribution. Therefore, this paper consider the Xinyang harbor to Doulong harbor coast should be the transition zone of the middle Jiangsu from the erosion in north to the deposition in south at present.