Study on dynamic change of wetland of Fujian based on RS and GIS

Wetland is one of the most important ecosystems and plays an important role in environment stabilization and species preserving. Fujian province is a coastal province of China possessing a considerable portion of wetland. In this paper, based on landscape ecology, remote sensing and geographical information system technologies, the dynamic change of wetlands in Fujian province of China is analyzed. ETM+ data of 1996 and 2002 that cover the study area were acquired. A wetland map of study area published in 1990 was also used. The images were preprocessed by geometric correction and geo-reference using the digital map, and were free of clouds. Then radiometric correction was done to make the image statistics and histograms from different time periods similar and comparable for the study area. Thus the wetlands in different times were identified by the images. The resultants were further analyzed jointly using ARC/INFO. The analysis result indicated that the wetlands in Fujian province mainly distributes around the bays along coast. In backland there were few wetlands except for some regions around a few reservoirs. The area of wetlands decreased greatly from 1990 to 2002, especially from 1990 to 1996. Since 1996 the decrease speed of wetland area had become slow. The result also indicated that the fragmentation of wetland landscape was evident in these years. The number and density of patch of wetlands had increased largely. The spatial distribution feature of wetland was studied by fractal theory. The fractal dimensional values were calculated respectively and they changed a lot. This means that the shape of wetland landscape had transformed. The wetlands around Jiulong river delta and Quanzhou coast were the main area where the area of wetland decreased evidently. In these areas, economic activities are the main reason for the decrease of wetland area such as the expansion of buildings, roads, farmland and so on.