GIS and Remote Sensing Based Analysis of Coastal-Wetland-Changes in Xiamen Western Bay

Remotely sensed (RS) images, sea charts, topographic map and bathymetric data in different times cover the last 100 years were used to detect the coastal wetland changes in Xiamen Western Bay (XWB). All charts and images were digitized with ArcGIS and projected to the same coordinate system. The areas of coastal wetlands in different periods were calculated based on the locations of coastal line and contemporaneous 6 m water depth, where was the limit of wetland according to the coastal definition of wetland in the Ramsra convention. Our study shows that the coastal wetlands in the bay has suffered great loss resulted from human activities. The wetland area decreased from 79.3 km² in 1907 to 55.9 km² at the end of 1950psilas, and further decreased to 46.6 km² in 1976 and 36.8 km² in 1993. Since then there was a little change in wetland area and the area of wetlands in XWB is 33.3 km² now. According to the maps and RS images, the changes of coastal wetlands were mainly resulted from the reclamation, especially the constructions of dikes of Gao-Ji, Ji-Xin, Maluan and Yuandang, causing the wetlands in XWB reduced dramatically, so the reopening of the dikes would improve the environment of XWB. However, it can not be restored to the original status.