The Research Of Wetland Dynamic Change In Changchun Based On Multi-temporal Remote Sensing

Wetland is a special landscape system formed by the interaction of water ecosystem and continental ecosystem, which is closely linked with human existence, development and multiply. As a special urban ecosystem, wetland plays an important role in increasing urban water area, maintaining biodiversity, improving water environment, adjusting urban climate and increasing tourism resources. Wetland is an irreplaceable important resources in urban. Owing the steadily expansion of the city and polluting emissions, a plenty of natural urban wetlands are in disappearing or losing its ecological attributes. Researching on the dynamic variation of wetland could provide scientific evidence to the government for the systematic planning, regulation and protection of wetlands.The main propose of this paper is to ascertain and analysis the area, types, distribution, changes and reasons of Changchun including Shuangyang, Jiutai, Yushu, Dehui and Nong’an from 1988 to 2014 by remote sensing and geographical information system. The main research contents include: land use classification of Changchun, information extraction of wetlands and statistical analysis of wetlands changes and reasons.Data resources consist of TM(1988), ETM(2000), OLI(2014) satellite remote sensing data acquired by Geospatial Data Cloud, 1:250000 base geographic database, meteorological data, demographic data and socioeconomic data and so on.In methods of this study, the pretreatment was carried on to remote sensing images, which including geometry correcting, image mosaicking and radiation calibration and so on. According to the wetland classification principles and Ramsar Convention classification system and fully considering the characteristics of wetland types and distribution characteristics of study area, the paper established a wetland classification system which accords with the requirements of the wetland classification in our country and fits wetlands characteristics in the study area. Changchun land use types were divided into 6 class and 7 secondary wetland types. Water information was extracted by the methods of water index and threshold segmentation. And then image enhance, interpretation marks and images classification was conducted by combining supervised classification with artificial interpretation. Post-Classification Process of Changchun land use types was conducted by Majority analysis methods. Using the accuracy evaluation method based on confusion matrix provided by ENVI software, evaluate the classification results. At last, use Arc GIS software to process the data comprehensively and form the Changchun land use status map and Changchun urban wetlands information status map. According to the monitoring results, analysis changes and reasons of Changchun urban wetland.The main results of this paper are as follows:(1) Adopting different methods of water index and threshold segmentation to extract water information has higher classification accuracy.(2) For other land use types, this study adopts the way of combining supervised classification with artificial interpretation, the total precision of the classification results are 89.45%, 91.97% and 94.45%.(3) Although remote sensing has the advantage of real-time and dynamic, water body information extraction and classification of other land use types show that researchers’ prior knowledge, mastery degree of actual situation of the study area, software operating proficiency and the understanding of classification algorithm all have effect on classification results.(4) This paper has ascertained and analyzed the area, types, distribution, changes and reasons of Changchun(1988-2000 and 2000-2014) preliminary. The change characteristics of urban wetland in Changchun was acquired: 1 The area of Changchun urban wetlands has a decreasing trend as a whole in 26 years, especially from 2000 to 2014.2In Changchun wetlands composition, paddy field proportion is the largest and the proportion of lakes and pits is small. 3Only paddy field and inland wetlands has an increased trend and others all have decreasing trend for 26 years.4The area of lake Poroto has shrieked seriously and natural wetlands has reduced a lot in study area.(5) There are two reasons for the decrease of wetlands: natural factor and human factor by analysis Changchun wetlands change. Human factor should be paid abundant attention.