Monitoring And Analysis Of Ground Deformation In Zhuhai City Based On Time Series InSAR

Geological disasters caused by surface deformation occur more and more frequently,especially the surface subsidence occurs in cities,which will endanger human social life and lead to human casualties and heavy economic losses.In order to protect the safety of human life and property,sustainable and large-scale surface deformation monitoring is very important.Traditional measurement techniques such as leveling have the disadvantage of time-consuming and labor-consuming,such as GNSS measurement will be affected by the signal is not continuous or artificial buildings affect its accuracy,and the above technologies are single-point measurement,which is difficult to meet the requirements of sustainable and large-scale.Synthetic Aperture Radar Interferometry(InSAR)makes up for this point very well.It has the advantages of all-weather,large range and strong penetration,and can measure small surface deformation with high precision.Based on this,the time series In SAR technology developed can use multiple SAR images to obtain long-term deformation results in the study area.It accords with the slow and cumulative characteristics of urban surface subsidence.Guangdong Province has carried out a special campaign to investigate and verify urban drainage pipes.In order to assess the risk of underground pipelines being damaged and broken due to surface deformation,time series In SAR technology is used to monitor surface subsidence,which provides some reference and reference significance for Guangdong Provincial Department of Ecological Environment.In view of the above purpose,this paper has done the following experimental research and results:(1)The principle of InSAR technology is described in detail,and the advantages and disadvantages of different In SAR technologies are analyzed and compared.In this experiment,29 Sentinel-1A data of Zhuhai urban area from September 2019 to October 2020 are used as experimental data,and according to the characteristics of relatively low Sentinel-1A resolution,SBAS technology is selected as the experimental processing method,in order to ensure the reliability of the experimental results,and the In SAR deformation data of Zhuhai urban area and its surrounding areas are obtained.Five areas with relatively large settlement are selected for analysis,and it is found that the settlement is caused by construction or land reclamation.(2)Field pipeline detection and level point measurement are carried out in Zhuhai.The national 2000 geodetic coordinate system of the underground pipeline map is converted into the WSG84 coordinate system by Arc GIS,and the joint pipeline map and ground deformation map are analyzed.Three regions are selected to extract the land subsidence information corresponding to the underground pipeline,and the land subsidence analysis along the direction of the underground pipeline is carried out.The subsidence rate map of each position along the line is given.The analysis shows that these areas are relatively stable and safe.(3)The accuracy of InSAR results was evaluated.This experiment is a precision analysis by comparing the results of In SAR with the results of measured leveling points.This paper first introduces the idea and method of unifying time datum and spatial datum in this experiment,and then compares the settlement curve of In SAR and leveling with MATLAB fitting,and finds that the error is in the millimeter level.