Application Of PSInSAR In Surface Subsidence Monitoring

Since the first records of the earth’s ground settlement,those regions around the world are subject to the different extent influence of surface subsidence. The earth’s surface subsidence is caused by natural and anthropogenic factors.The surface subsidence caused by he human factors can be summarized as the goaf formed from the excessively mining the underground mineral resources and the static loading resulted in some major engineering constructions.The surface subsidence has become an important factor affecting economic development, and thus monitoring surface subsidence will be of great significance.At present, commonly used methods for monitoring surface subsidence are the traditional geodetic leveling, GPS measurements and geodimeter measurements. These methods have their own technical characteristics,and they are to establish a fixed observation network in the operation area, carrying on the multiple independent repeat observed. Although can realize the high precision observation, but it takes a lot of manpower and material resources, and to monitor the density is too low to be difficult to achieve large-scale monitoring. It needs the effective monitoring methods to monitor the arge-scale surface subsidence, so synthetic aperture radar has been more and more used to monitor the surface subsidence because of its all-time, all-weather, strong penetration ability, obtained amplitude and phase information and active remote sensing, etc..DInSAR used to monitor the surface subsidence can obtain the cm-level or even mm-level deformation informations. But for the long time baseline surface deformation monitoring, the accuracy of DInSAR technical monitoring results can be affected by spatial and temporal loss of coherence which caused by the spatial and temporal resolutions, the doppler center frequency difference. So the PSInSAR is often used to solve those problems in the long slowly surface deformation process. Those PS points after a long interval can maintain a stable scattering properties, no spots noise effects and well coherence because of its strong echo signal and the small geometric size which is far less than the spatial resolution of images.In this paper, the PSInSAR technology has also been discussed on the study area, combined with the study area’s present situation, to develop the experimental design and workflow monitoring of surface subsidence. Combining the working process, the first step is data preprocessing, included the raw data’s collecting such as SAR, DEM, fine-orbit data, the TM/ETM images, field survey data, cutting, transforming the data format, unifying the coordinates and projections. After preprocessing, the next step is interference and PS processing. Combined with an external reference DEM, the surface subsidence suspected region can be delineated to extract deformation information.By processing9scene SAR images of the experimental area, this paper focuses on some key technology such as selecting the public master image,image registration and phase unwrapping, obtains the deformation data and deformation diagram of study area. At last, the survey region has been divided into northern, central and eastern three settlement areas. Combined with the regional geographic environment, this paper has briefly analysed the reasons for the surface subsidence and put forward some reasonable suggestions.And the data processing methods and processes have some references for monitoring surface subsidence.