论文部分内容阅读
As urbanization fleetly spreading in Taiwan,surface subsidence,resulting mostly from pumping groundwater,becomes a critical issue to be faced in line of infrastructure safety.Monitoring of city surface movement is essential before prevent ative measures can be designed and impl emented.This paper presents an island wide monitoring of land surface subsidence using constellation of satellite SAR images offered by COSMO ‐SkyMed and TerraSAR ‐X with 1 ‐3 meters resolution.By carefully selecting interferometric pairs and precise InSAR processing,high accuracy of small scal e to l arge scal e subsidence can be detected and measured up to centimeter resolution.Without detail height of building or man ‐made structure,offset of interferograms are identified and can be removed wi th known cont rol poi nt s.Thi s offset I ndeed provi des hei ght I nf ormat I on I f properl y processed.Exampl es are presented in several sites with reasonabl e high accuracy.In most area where the subsidence was documented,the subsidence is expanding outwardly.There is also a clear trend that the expanding towards a high ‐speed railway running north ‐southward al ong western isl and.This an alarming signals by any means.For some areas,seasonal effects from rainfall are clearly visible causing subsidence ‐uplift cycling.Extensive examples demonstrate that by constellation of current operating SAR satellites,both spatial and temporal observation scale are greatly improved,making island ‐wide monitoring using InSAR even more practical.