Research And Application Of Ground Subsidence Monitoring Based On PS-InSAR Technology

With the rapid development of economy and the fast expansion of cities, the underground resources consumption has been significantly increased, thus deepening the influence of land subsidence. And long-term monitoring of land subsidence is one of the most effective measures to prevent and control land subsidence.The common methods to monitor land subsidence include precise leveling and GPS, which have their own advantages but always consume a large amount of money and efforts. Differential Interferometric Synthetic Aperture Radar(D-InSAR), developing rapidly in recent years, has been widely used in the monitoring of land subsidence because of its active feature and the properties of all-weather,and all-day. However, the application of D-InSAR is limited with the influence of decorrelation and atmospheric effects. InSAR time series analysis method, i.e. permanent scatterer differential interferometry(PS-InSAR), has been proposed to overcome the limitations above and has drawn wide attention after the first successful application.Based on using PS-InSAR technique to monitor ground subsidence issues in Los Angeles in USA, showing the largest subisidence magnitude/rateof Los Angeles from 2003 to 2007 is 15.93 cm and-3.81cm/a. Compared with GPS data, the error of PS-InSAR monitor is within ±2cm.The principles of Synthetic Aperture Radar is introduced first, then the principles of D-InSAR to measure height, differential interferometry to monitor surface deformation and PS-InSAR to monitor land subsidence are described systematically. And the key technologies, such as common master acquisition selection, image registration and permanent scatterer recognition relative to PS-InSAR, are concentrated on and explained with related experiments. Based on the ENVISAT ASAR data of 18 scenes in research area from October of 2003 to November of 2007, the integrated correlation coefficients of SAR image for each scene are calculated to select common master acquisitions. Combining the DEM data and precise trajectory data, the selected common master acquisitions are processed by interferometry, then permanent scatterers(PS points) are optimized by dual threshold method. And the chosen PS points are processed throughdifferentialinterferometry, network structure and phase unwrapping, then the land subsidence magnitude and rate of PS points in the experiment area are obtained. Correlation analysis of the land subsidence magnitude and the underground water data are conducted. Finally, the land subsidence magnitude are verified by the comparison of GPS historical monitoring data, which shows that the monitoring results of land subsidence by PS-InSAR are accurate and reliable.