Ecological Monitoring&Evaluation Based On Remote Sensing Technology And Comparision Of Different Island Cities

There are rich marine resources and many islands in China.As a significant part of the marine ecosystem,island,with its special geographic location and abundant resources,plays an important role in defending national security and national marine rights.Before 1980s,due to government policy and less developed economy,the construction and development of islands was very slow.Coming into 21st century,government has carried out positive strategy about development of the ocean,which leads to development boom of islands.Extensive human activities put the island ecosystem at unpredictable risk.The sustainable development and ecological environment quality of islands have been the hot spots of society.So it is of great and practical significance to evaluate the present ecological environment condition and dynamic changes of island cities.Finding out the ecological problems and the solutions can guide the ecology protection during the development of islands.This paper has selected four representative emerging islands in China as research areas,which are Pingtan Island in Fujian Province,Chongming Island in Shanghai City,Zhoushan Island in Zhejiang Province and Dongshan Island in Fujian Province.Using the method of RSEI which is totally based on remote sensing technology,this paper evaluates and compares the ecological environment condition about the four islands during their urbanization process.By revealing driving forces which cause ecological changes in different islands,different island development patterns are compared and the better strategy for protecting ecological environment are explored.The main idea and results are as follows:Two remote sensing images before and under the fast urbanization are obtained.Based on RS thematic information extracting technology,four representative evaluation factors are got,which are Wetness,Greenness,Hotness and Dryness.By taking them into Principal Component Analysis,the Remote Sensing Ecology Index(RSEI)is generated.Using RSEI this paper evaluates the ecological environment condition of different islands in different time.According to the results,the overall ecological environment condition of Pingtan Island has been in intermediate level and downwards.During the research period(from 2004 to 2013),the mean value of RSEI has changed from 0.4406 to 0.4506,which means the ecological environment condition has been improved.For Chongming Island,the ecological environment condition has been in superior middling level.During the research period(from 2002 to 2014),the mean value of RSEI has dropped from 0.6862 to 0.6141,which means the whole ecological environment condition has a little decline.Zhoushan Island’s whole ecological condition has also been in superior middling level.During the research period(from 2006 to 2014),the mean value of RSEI has dropped from 0.6109 to 0.5586,which means the down of the ecology condition.The overall ecological environment condition of Dongshan Island has been in superior middling level.During the research period(form 2006 to 2014),the mean value of RSEI has dropped from 0.6024 to 0.5195,which means the ecological environment condition of Dongshan Island has been depraved.On the basis of land use/cover classification and change detection,this paper analyzes the driving forces of the ecological environment condition changes.Although the land use/cover changes of the four islands have shown different trends.But all of them have shown that during the development of islands,the area of building and unused land have increased shapely,while the area of farming land,and water area has decreased markedly.In order to increase the land reserves,some islands has cultivated and silted marshland,and some islands has conducted sea reclamation project.The change of land use/cover has led to the change of the Wetness,Greenness,Hotness and Dryness,thus causing the change of the ecological environment condition.Further analysis has shown that the government policy and economic development are the fundamental driving forces of ecological environment condition change.By comparing the ecological condition of different islands,this paper proposed solutions for protecting ecological environment of Pingtan Island during the island development,and put forward some related suggestions.