Research On Surface Deformation Monitoring In Kunming By Integrating Time-series InSAR And GNSS Dat

Kunming is located in the central part of Yunnan Province.As the capital city of Yunnan Province,urban disasters have become increasingly frequent in recent years due to urban development and construction,large-scale groundwater extraction,mining and other factors,making the area affected by ground deformation,thus threatening the safety of people’s lives and property,and limiting the sustainable economic development of the city.Therefore,it is of great scientific significance to monitor the ground deformation in urban areas.The traditional monitoring method is to set up a leveling network,but due to the large workload,time-consuming and insufficient spatial sampling rate of this method,especially in the case of a wide monitoring range,it is difficult to systematically,comprehensively,real-time and reliably grasp the distribution and development law of regional surface deformation.InSAR technology has the advantages of large area,high precision and high resolution,and is widely used in various deformation monitoring fields.However,because SAR is a side-looking imaging system,the monitoring results obtained by InSAR technology are the one-dimensional projection of the real surface on the radar line of sight,which cannot reflect the three-dimensional deformation of the surface in the east-west,north-south and vertical directions,which greatly restricts the application prospects of InSAR technology.In response to the above issues,this article proposes to use the Variance Component Estimation(VCE)method to fuse the calculated Continuous Operating Reference Stations(CORS)station monitoring data with the lifting rail Sentinel-1A monitoring data obtained by Small Baseline Subset InSAR(SBAS-InSAR)technology.The main research and achievements of the paper are as follows:(1)By solving 8 KMCORS data in the research area,monitoring data from January2019 to December 2020 were obtained.Common mode error was removed from the original time series,and the horizontal velocity field under the ITRF2014 framework and the three-dimensional velocity field under the Eurasian plate background field were obtained.And perform Kriging interpolation on KMCORS discrete points,and use the interpolated results for the fusion of InSAR and GNSS data.(2)Based on the Stanford Method for Persistent Scatterer(Sta MPS)platform,SBAS-InSAR technology was used to perform temporal analysis on 25 scene descending and 50 scene ascending images,and GACOS products were added to estimate and correct the atmospheric delay in the interferogram.The results showed that introducing GACOS can alleviate the atmospheric delay error in the interferogram.We obtained the LOS deformation rate and cumulative deformation variables in the study area from January2019 to December 2020,and analyzed the spatial distribution characteristics of settlement in Kunming urban area.Perform accuracy verification on the deformation analysis results of SBAS-InSAR using both internal and external coincidence accuracy verification methods.This involves converting the LOS deformation rate results of the lifting track to vertical backward,randomly extracting deformation points in the study area,and comparing and analyzing the same name points in the lifting track mode to obtain correlation;And point-to-point verification was conducted using the vertical deformation values monitored by CORS and the deformation values of the lifting rail after turning to the vertical direction.The results showed that the deformation rate of the lifting rail obtained using SBAS technology was in good agreement.And the causes of settlement were analyzed from two aspects: human factors and natural factors.(3)In response to the limitation of InSAR technology that can only obtain onedimensional deformation information towards LOS,a posterior variance component estimation method is proposed,which utilizes InSAR orbit elevation and descent data to fuse with KMCORS data monitoring results to obtain a three-dimensional deformation field.To verify the effectiveness of the method proposed in this paper,three fusion schemes were designed and the trend consistency between the results and the threedimensional deformation rate of the interpolated KMCORS was verified.The accuracy of the deformation rate in the horizontal and vertical directions of this method is higher than the other two schemes,verifying the effectiveness of the experimental results of this method.