Monitoring Urban Ground Subsidence by Using Differential Interferometry Space-born Synthetic Aperture Radar

Differential Interferometry Synthetic Aperture Radar (D-InSAR),as a new technique to observe the ground,has been widely used to monitor urban ground subsidence,which attracts many researchers' attention in the world.By applying the principle of phase difference of the images at different time,micro-deformation within large area can be retrieved by D-InSAR.Typical D-InSAR includes two-pass,three-pass and four-pass models;as for monitoring ground subsidence at long time scale,some methodologies of dissimilar process,such as PSI,SBAS,CRT and CAT,were gradually promoted and tested by researchers,and their core is to retrieve coherent point targets exposing on interferograms.Related applications of D-InSAR on monitoring ground subsidence at home or abroad are further summarized,it proves D-InSAR effective for subsidence detection,and theoretic precision can be up to millimeter level.Primary theory and framework of data processing also have been formed.However,D-InSAR still has some errors in subsidence detection mainly due to the effect of the vegetation cover and weather variation.Up to now,detection of subsidence appearing in some regions is still under restriction.How to reduce the errors and what model would be used for measuring subsidence with optimization are still to be studied.In the future,D-InSAR will be more widely applied with more data resources. More attention will be paid to combination of datasets from multi-sensors to monitor subsidence with long time span.Monitoring urban ground subsidence in the future will be focused on integrating GPS and Leveling with D-InSAR.