Characteristics of Wetland Changes in Hangzhou Bay in Zhejiang Province Based on GIS

Based on Landsat TM images in 1990, 2000 and 2005, this paper studied the characteristics of wetland changes in Hangzhou Bay in Zhejiang province using remote sensing and GIS technologies. The results show that: (1) the wetland area decreased 1893 km 2 in Hangzhou Bay in Zhejiang province from 1990 to 2005, and it decreased obviously faster after 2000 than before. (2)The decreased wetland mostly transformed into construction land and glebe. In particular, the transform from wetland to construction land was prevalent. The increased wetland mostly changed from sea and glebe. (3)The paddy field area decreased 2213.77 km 2 , and the aquiculture water area increased more than 250 km 2 . The change extent of the tidal flat was the biggest and the change rate of it was the fastest, while the river changed little. (4)The estuary of Qiantangjiang River and the Hangzhou Bay south coast were the typical areas of wetland change.