Change Detection Of Wetlands Over Fujian Province By Remote Sensing

Coastal wetland is a part of wetland system with active human activity, of which studies become popular as its development of economy and change of landscape pattern. Fujian is one of the provinces in China with abundant coastal wetland resources. Its rapid development of economy and serious environmental problems make Fujian a typical region on coastal wetland study. But most researches of coastal wetland over Fujian Province were partial, and analysis under the province scale was rare. This research chose each a place in Xiapu and Putian as sample area to research method on coastal wetland information extraction, and then change of landscape pattern of coastal wetlands in Fujian Province from 2000 to 2009 was quantitatively investigated by the RS and GIS. The main contents and conclusions are summarized as follows:(1) The coastal wetland information extraction method research.Choosing Xiapu and Putian as the two sample regions, the object-oriented method integrated with iterative segmentation, SVM classification and optimization rules to improve wetland classification accuracy. The results showed that:the iterative segmentation method obtained multi-scale segmented boundary, and the SVM classifier based on iterative segmentation was with good ability on wetland information extraction. Space optimization rules made a good use of spatial relativity and significantly improved the accuracy of results.(2) Fujian coastal wetland information extraction.Integrated with authoritative wetland classification system, the character of wetland resources on images and field data, the classification system of Fujian Coastal wetlands types and their interpretation keys were established. Classification of coastal wetland over Fujian was obtained by Landsat ETM images and ALOS AVNIR-2 images through object-oriented method. In order to reduce the impaction of tide, MODIS data obtained in low tidal time were used to extract mudflat information to update the mudflat information among the previous classification and then got a complete result of Fujian coastal wetland distribution.(3) Analysis of Landscape change of coastal wetland in Fujian province.Using landscape pattern indexes and land-use conversion matrix, quantitatively analyzed the change process of the coastal wetland landscape pattern in Fujian Province from 2000 to 2009. It can be observed from our results that:(1) the area of coastal wetlands was reduced by 12714 hm. The natural wetland area was reduced by 44297 hm, while the artificial wetland area was increased by 31583 hm2. (2) Shannon diversity indices and edge density increased and plaque combined indices decreased, which speed the wetland landscape fragmentation. (3)The preservation ratio of natural wetland became high while artificial wetland low, and massive wetland were converted to non-wetland, non-wetlands and natural types were converted to artificial types. (4)The dominant conversion processes indicate that, with the developing in coastal zone, the aquaculture played an important role in the pattern changes of coastal wetlands.