Potential investigation of SAR data in monitoring island and its surrounding environment: 8-year dynamic monitoring of South five-island in Miaodao archipelago of China
Xiaolong Wang(1) and Jie ZHANG(1)
First Institute of Oceanography, SOA,
6, Xian-Xia-Ling Road, High-Tech park,
Island is important marine resource. For the complex environmental dynamics dominated by wave and tide and increased human activities, there is a great need for high resolution, synoptic information on the dynamic changes of it. Optical remote sensing has been used to characterize the environmental changes of island. Microwave remote sensing, as imagery from clouded areas can be used, has great potential for mapping and monitoring these changes. This study is aims to discuss the ability and demonstrate the application in monitoring and mapping the dynamic changes of island and its surrounding marine environments using SAR imagery. Data in support of the research include RADARSAT SAR and ERS SAR. The focus is on the South five-island area of Miaodao archipelago in the intersection of Bohai sea and Yellow sea. Based on the sensitivity of SAR to the edge, an edge detection approach is developed for the coastline extraction. Using the texture analysis method, statistical features of texture combined with the varied statistical windows are calculated and selected for the SAR images classification. Through matching the extraction results with the ground truthing, a conclusion that extraction accuracy can reach 80 percent or more is drawn, and potentials of RADARSAT SAR and ERS SAR in monitoring island and its inshore environments are discussed and analyzed. In the case research, 8-year dynamic changes of the South five-island and its surrounding marine environments, form 1997 to 2005, have been studied. Information of the environmental changes in this region, including terrestrial environment, coastline and inshore conditions, is derived and the causes are analyzed.