Analysis Of Change And Driving Force Of The Coastline Of Mainland In Nearly 35 Years

Coastal zone is the area of interaction between the ocean and the mainland,with rich resources and region advantage,but in recent years,with the enhancing of human activities,it is facing huge challenges.Especially in China,since the reform and opening up,with the rapid development of coastal areas' economy,coastal areas is bearing a huge social and natural pressure.In order to ensure the sustainable development and utilization of coastal areas,it is necessary to study the characteristics of the coastline and the spatio-temporal changes of coastline contributes.Base on series of Landsat satellites remote sensing imageries and topographic maps,five coastline positions of mainland China at 1980,1990,2000,and 2015 were extracted.Then evaluate accuracies and to control qualities of five coastline positions with the field surveys and topographic maps.Furthermore,we choice Yangtze Estuary and Hangzhou Bay As a typical area,based on Resource-Process-Response model,combined with the social economy and ecological environment data,research the dynamic of coastline change,and obtained the following conclusions:(1)Conclusions about defining the river-sea boundary based on B-L curve.Estuary is a Complex and special area.Generally,there are many parameters to define the boundary between the river and the sea.This study analysis the relationship between the demarcation method base on the geometric and geomorphologic character and other estuarine parameters.For each of these,a geomorphic node maybe the most suitable to determine the location of boundary.For different kind of estuaries,we constructed the B-L curve(B is the channel width and L is the distance along the central axis of the river),defined the river-sea boundary base on the geomorphic node.The result showed that:For the blind estuary which has ephemeral sand bar or the barrier estuary,the rate of river width variation at the geomorphic node between?0.5 and 0.For the long and narrow estuary,the rate of river width variation at the geomorphic node between 0.5 and 1.2.For the Funnel-shaped estuary,the rate of river width variation at the geomorphic node between 0.6 and 1.5.For the Funnel-shaped delta,the rate of river width variation at the geomorphic node between 1.2 and 4.5.(2)Conclusion about the characteristics of coastline on Mainland China.In the past thirty five years,the coastline mainly expanded seaward and coastal engineering construction were the leading factor in coastline evolution.As a result,the index of the development and utilization of coastline on Mainland China was getting higher and higher,and the spatial distribution of it is significant,north regions is strengthen than south regions;estuary regions is strengthen than hilly regions;economically developed regions is strengthen than economically backward regions.People gathering in the coastal zone what is main reason for the change of coastlines,and the influences defer in different place.Furthermore,In Tianjin City,Shanghai City,and Guangdong Province the intensity of the development and utilization of coastline showed a high correlation with the gross industrial production.(3)Characteristics of coastline change in Yangtze Estuary Hangzhou Bay base on Resource-Process-Response model.Evaluating Suitability of coastline resources in Hangzhou Bay,Yangtze River Estuary,and divided functions,then we concluded that 23.62%of the coastline have the priority of developing;19.29%coastline is suitable for travel and life;17.81%coastline should be protected strictly;and 39.28%could be used as reserve bank.Generally speaking.Compared with the status quo,the coastline resource in the study area is very rich,and the coastlines' utilize is depend on the coastlines' development potential.For the estuary area,the material come from upstream is the important factor which influence the change of coastline.When the material is rich enough,the growth of mud tidal flat is faster than the sea reclamation.On the contrary when the material is not rich enough,the speed of sea reclamation is slow down.In the years 1980?1990 stage,natural factors are relatively strong,human activities mainly for the construction of shoreline protection;in 1990?2000 human reclamation activities,especially farmland and farming reclamation;in the years 2000?2010 the impact of human activities is very strong,the city development,port construction and reclamation activities for the most active period.In the past 35 years,with the gradual improving of development and utilization of the coastline,the coastlin's structure has been shown to be diversified.For specific,the main component of shoreline over 20 percent from two kind of shoreline to three and more kind.At the same time,the fractal dimension of the coastline showed a trend of increasing first and then slowing down recently,and it had a good Relevance with the intensity of the reclamation and the construction of the port.The development and utilization of Yangtze Estuary and Hangzhou Bay coastline and social economic factors are inextricably linked,the strength of developing and utilization coastline and coastal city of GDP,the strength of industrial output,the population has a good corresponding.In all the elements,the linear correlation between the population and the strength of developing and utilization coastline is highest,it's up to 0.98,which indicates that the huge population pressure is an important factor in developing and utilizing the coastal resources.