Coastline Extraction And Change Monitoring By Remote Sensing Technology In Dalian City Based On GIS/RS

The changes of coastline have been highly concerned by the coastal countries and regions because of the influences on the balance of the marine ecological system as we all know that coastline is the most important element in coastal zone.Although there are numerous situations in detecing coastal information,simple determination of the land-water boudary can be very important and practical.Therefore,to accurately extract the coastline and monitor its special-temporal changes was the main task of this thesis.The Dalian coastal zone with its abundant coastal types is located in the core region of Liaoning coastal economic zone and in recent year its sea use has been influenced by economical activities greatly along with distinct coastline variations.To extract the coastline and study its variations in time would provide reference data and standard for future development in Dalian and Liaoning coastal areas.In ENVI environment,this paper analyzes every kind of coastal type's ground object characteristics and establishes remote sensing interpret tags for the coastal segments in accordance with the types of the coast.This paper designs different image preprocessing schemes in accordance with the characteristics of each coastal type of each segment to obtain basic images of each segment' s coastline.And this paper uses automatic detection algorithm to extract years of coastline remote sensing data in the research area,use ArcGIS to implement data vectorization and quantify Dalian coastline variation information of the past 20 years.The results of sea reclamation areas and the analysis of dynamic evolution pattern in the research area are as follows:(1)In order to improve the accuracy of coastline extraction,based on the differentiation of coastal types,this paper discusses the comprehensive extraction method.Sandy coastline is on the boundary of the dry beach face and wet beach face.And MNDWI method can increase the differentiation of the dry beach face and wet beach face and help further improve the coastal extraction accuracy;After texture calculation,the edge feature of developed and utilized muddy coast is more obvious;With high-pass filtering,the coastline feature of bedrock coast and artificial coast' contour feature may be further strengthened.With the help of Canny edge detectors,after preprocessing of different kinds of images,its coastline can be extracted automatically.The unrelated dark areas on the wet beach surface on unused muddy coast can be removed with morphological algorithm and using the C-V model algorithm can improve the accuracy and continuity of this kind of coastline extraction.Through the precision verification analysis shows that the extraction of the coastline of basic control accuracy in two pixels within the error range.(2)For the last 20 years,the spatial-temporal changes of Dalian coastline are obviously.From early 1990s to 2000,the length of Dalian coastline decreased rapidly,the decreased number is 142.3 km;After 2000,the variation of the length of its coastline changed from slowly increasing stage to the rapidly increasing stage and finally tend to increase smoothly.Overall,the artificial coastline increases while natural coastline decreases through out the years.Spatially,the length variations of coastlines of Dalian Changxingdao and the sea area close to Zhuanghe are the most obvious.(3)Since the 1990s,the area of sea reclamation in Dalian keeps expanding into the ocean.The change of number is 510.82km.From 2006 to 2012,the cumulative growth area of sea reclamation reaches its highest point.The number of add is 41%about 24 years.