Application of ASAR PSI techonology to ground deformation detection in mega-cities of the Pearl River Delta Region in China

In this study, we present the application of Persistent Scatterer Interferometry (PSI) technology with ENVISAT (European satellite) Advanced Synthetic Aperture Radar (ASAR) images to detect the ground deformation in the Guangzhou urban area and Hong Kong International Airport (HKIA). A map of ground deformation rates in Guangzhou with scattered points shows that the maximum subsidence (rise) rate is up to -26 to -20 mma^-1 (16-21 mma^-1), implying the study area as an active zone of the ground deformation. Based on the point targets, a contour map of ground deformation rates was then generated. The map indicates that three major subsidence zones are located in the middle-west, east, and southwest of Guangzhou urban area, respectively. Six ground collapse accidents that occurred in Guangzhou during 2007-2008, within these subsidence zones, qualitatively validated the results. In the case of detecting ground deformation in HKIA, the ground truth data provided by the Airport Authority Hong Kong were used to correct the model, which is then applied to analyze the systematic errors existing in ASAR PSI-detected ground deformation rates. 2250 corrected ASAR PSI-detected points of annual ground deformation rates were used for the statistical analysis. The obtained results agree the Gaussian distribution well in our case studies.