An Evaluation of the Performance in Ground Settlement Monitoring in Hong Kong Using Satellite Radar Remote Sensing Technology

In recent years, Persistent Scatters (PS) Synthetic Aperture Radar Interferometry (InSAR) technology has been proved to be a powerful tool that can provide high resolution information on topology and ground displacement monitoring of up to millimetric accuracy. In this project, we studied the ground deformation of the area of interest (AOI) in Hong Kong urban area by means of PSInSAR technology with multi-temporal techniques. The deformation map of AOI showed a relatively stable status with 0~-15mm/year subsidence in partial regions. For evaluating the millimetric accuracy performance of monitoring outcomes, a set of corner reflectors (CR) are deployed in the monitoring region. For the validation test, the CRs are either lifted or lowered, and the displacements are recorded by optical leveling. The accuracy of PSInSAR monitoring is then evaluated quantitatively by comparing the estimated displacement from SAR images with optical leveling data. The results of CR test showed a very high correlation between the displacement retrieved from InSAR analysis and that from ground survey; the deviation is less than one millimeter. In conclusion, PSInSAR method is validated for its capability of achieving millimeter level accuracy, meanwhile much more convenient than conducting ground survey in monitoring ground subsidence.