Time-Series InSAR-Based Ground Subsidence In Xiongan New Area Monitoring And Analysis

Xiong’an New Area is another new area of national strategic importance after Shanghai Pudong New Area and Shenzhen Special Economic Zone,which is a major national event of the millennium.The continued development of the new area will inevitably lead to huge infrastructure construction and groundwater resources exploitation,which in turn brings the risk of ground settlement disasters.Ground settlement hazards can damage infrastructure and hinder the sustainable development of society.It is of great significance to monitor the ground settlement in Xiongan New Area and analyze the spatial and temporal characteristics of settlement evolution and causes of settlement,so as to provide a basis for the construction and development of the new area and the prevention and control of settlement hazards.Traditional ground settlement monitoring methods cannot meet the demand for largerange,long-time and low-cost monitoring.Interferometic Synthetic Aperture Radar(InSAR)and its extended methods are suitable for ground subsidence monitoring research because of its advantages of wide coverage,all-weather monitoring and low cost.In this paper,118 Cband Sentinel-1A orbit-raising images are selected to monitor the surface deformation of Xiongan New Area using the time-series InSAR technique.The temporal and spatial evolution characteristics of the subsidence area are analyzed using the temporal principal component analysis method and the regional subsidence center of gravity method,and the causes of subsidence triggering are analyzed.The main research contents and conclusions are as follows.(1)The annual average deformation rate field and deformation time series in the radar line of sight direction from May 20,2017 to June 16,2021 were obtained for the Xiongan New Area using the SBAS-InSAR method to process Sentinel-1A image data.The monitoring results show that the annual average deformation rate of the new area ranges from-86.3 to 30.2 mm/year,and there are three major subsidence funnels.The subsidence funnel in the northern part of Xiong County has the largest subsidence magnitude and distribution area,while the subsidence funnel in Anxin County is smaller than the Xiong County subsidence funnel in terms of magnitude and distribution area.(2)In order to solve the limitations of traditional PS-InSAR in non-urban areas where PS points are sparse and a priori deformation rate is required,the Time Series Combination PSInSAR(TSC-PSI)method based on StaMPS method is proposed to increase the number of monitoring points by taking into account the time-domain coherence points.The TSC-PSI method is used to monitor the deformation in Xiong County,a region with severe subsidence in Xiongan New Area,and obtain the annual average deformation rate field and deformation time series in Xiong County.The monitoring results were compared with those of the traditional PS-InSAR method to verify the reliability of the TSC-PSI method.(3)The spatial and temporal evolutionary characteristics of ground subsidence in Xiong County were analyzed.The first two principal components contributed more than 85% of the variance,and the spatial and temporal characteristics of ground subsidence corresponding to the principal component scores were analyzed in detail.The regional center of gravity method was used to calculate the center of gravity migration of the subsidence funnel,and the center of gravity of the subsidence funnel migrated 1152 m during the four-year period,and the location of the center of gravity of the subsidence funnel tended to be stable with time.The data on ground subsidence in Xiong County were collected,and it was inferred that the development and utilization of geothermal resources was the main cause of ground subsidence in Xiong County and even in Xiong’an New Area,and that transient fluctuations in surface deformation were caused by agricultural irrigation and concentrated rainfall.