Remote sensing monitoring and analysis of expansion characteristics of Chongming Island in Shanghai, China

Mapping and detecting landscape pattern changes and features has become an urgent task due to the increasing pressures of rapid urbanization and associated environmental problems. This is exactly the case of Chongming Island which has been proposed to become an “ecological” island in the near future. A dynamic study on the island's expansion, vegetation and land use/cover shift patterns over the past 30 years was carried out based on Landsat and ALOS satellite remote sensing imagery by employing an object-oriented classification approach incorporated with vegetation indices (NDVI and NDVSI). NDVSI index which was developed in this study was fused with red and infrared bands to improve the resolution and extract the vegetation and land use type by NN arithmetic for the Landsat MSS image. It is found that vegetation area almost remain unchangeableness with the expanding the Chongming island from 1979 to 2009, while the area of built-up and water body were increased obviously. Most expansion area of the island is added to urbanization and rural settlements development, wetland and water body. In the past 30 years, the proportion of vegetation area to the total area of Chongming Island decreased from 71% to 52%, by contraries, the proportion increased from 5% to 14% for built-up area. The population in 2009 had been more than 2 times of that in 1979. The change of vegetation area in Chongming Island does not correspond proportionally with the growth of island , but the temporal changes of the built-up areas are highly correlated with the population changes, the revenue of local government, which reflect the fast development of economy and urbanization.