| Nearly half of the earth's population lives in coastal areas,which are important areas for population gathering and economic development.Nowadays,with natural and human factors such as climate change,sea level rise and island development and utilization,islands have become a hot topic that has attracted much attention,and is the focus of China's marine economy,social development,ecological environment and territorial security.To a certain extent,the research on islands is not enough to support our actions,the monitoring of island information changes is relatively small,the understanding of island information evolution characteristics and changes is not comprehensive,and high-quality data is not comprehensive or even vacant.Island information change monitoring is the basis of island environmental control,resource development and ecological protection,strengthening the monitoring of island information change can more scientifically understand the characteristics and laws of island change,promote the sustainable development of island resources,environment and ecology,and better promote the construction of a marine power.In this thesis,Dalian Changhai County is selected as the research area,and the specific research work is as follows:(1)Taking the remote sensing image of Landsat8 in the research area on July 9,2015 as experimental data,the accuracy of island shoreline extraction was determined by comparing the threshold density segmentation method,Sobel operator edge detection method,Roberts operator edge detection method,and Canny operator edge detection method.(2)Based on the landsat ETM+/OLI remote sensing data of 2010,2013,2016,2019 and2021,the island information of the study area was sequentially extracted.(3)Based on geospatial analysis,fractal dimension thinking,mathematical statistics and other methods,the number of islands,shoreline information,morphological information,vegetation cover information changes are studied,and the specific analysis of Hiroshima Island,Zhangzidao Island,Haxian Island and Gexian Island is selected.(4)Based on the monitoring results of island information change in the study area,the driving force of influencing factors of island change was analyzed.The specific research results are as follows:(1)After fitting comparison,the accuracy verification of the island shoreline of the research area extracted by the Cany operator edge detection method adopts a double threshold,which has a small impact on noise and is closest to the real situation of the island shoreline.(2)During the period from 2010 to 2021,the number of islands extracted from 2010 to2021 in Changhai County,Dalian was 117,126,124,126 and 127,respectively,and the number of islands had a certain upward trend;the length of the island shoreline increased by46.88 km,and the growth rate from 2010 to 2013 exceeded the sum of the total growth from2013 to 2021,and the coastline length and spatial resolution of the islands were roughly negatively correlated,and the coastal structure was complex.Relatively stable and stable continued to rise;the cumulative increase in island area was 15.52km2,the corresponding rate of change was positive,the sum ratio of the growth from 2010 to 2013 and the total growth from 2013 to 2021 was about 1:2,and the island shape index in the study area was 7.8957,8.3427,8.4260,8.3799,8.5509,the average value is 8.3190,the complexity of island shape is relatively high and upward trend,the overall expansion trend of the study area is oceanic;the vegetation cover area is extensive and upward;the change of the example island is consistent with the whole,and the larger the island,the higher the morphological complexity of the island,etc.(3)The driving factors affecting the change of island information are mainly natural factors(geology,geomorphology,ecological environment,climate,etc.)and human factors(economic development,urbanization,policy factors,etc.). |
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