Study On Surface Deformation Of ShenZhen Reclamation Area Based On Dual-polarization SAR Data

Time series InSAR technologies,represented by permanent scatterer technology(PS)and small baseline set technology(SBAS),have achieved great success in surface deformation acquisition.However,in previous studies,researchers often applied unipolar SAR data or indiscriminately use unipolar information in multipolar SAR data to conduct experiments when using these technologies,thus ignored the influence of polarization information in data on surface deformation extraction.With the continuous lift-off of multi-polarization satellites,the most promising research area in the field of remote sensing SAR is to explore the influence of polarization information in polarizing SAR data on surface information extraction results.Therefore,this paper analyzes the ground information acquisition effects of different polarization modes through experiments,so as to select the optimal polarization mode as the data source for subsequent processing,aiming at obtaining more accurate ground information,mining the polarization information of data,and improving the utilization efficiency of polarized SAR data.This paper aims to mine the polarization information of the data by analyzing the effect of surface information acquisition under different polarization modes and then selecting the optimal polarization mode as the data source for subsequent processing.Finally,it improves the utilization efficiency of polarized SAR data and obtains more accurate surface deformation information.It is an exploratory study on using polarizing SAR data for surface information extraction,which expands the application scope of polarizing SAR data,and provides inspiration for future studies on using polarizing SAR data for surface deformation.The research results of this paper are as follows:1.Based on the coherence,the optimal polarization mode of sentinel-1a dual-polarization SAR data is selected.In this paper,DInSAR technology was used to process sentinel-1a dualpolarization SAR data to obtain interferogram,differential interferogram and surface deformation extraction results of different polarization modes in the same research area.Using coherence as the selection criterion,the comparison results show that the interference fringe of VV polarization mode is clearer and more obvious than that of VH polarization mode,indicating that the coherence is higher.The coherence coefficient corresponding to the peak value of the VV polarization mode is 0.02 higher than that of the VH polarization mode on the whole.Pixels with the coherence of 0.4 or above account for 5.9% higher than that of the latter.Pixels with coherence of 0.6 or above account for 5.6% higher than the latter.Pixels with a coherence of more than 0.8 account for 2.3% more of the latter.Finally,the experimental results show that the data of VV polarization mode are superior to that of VH polarization mode in surface deformation extraction in Shenzhen area.2.Based on PSInSAR technology,deformation range,deformation characteristics,average settlement rate and time series shape variables of Shenzhen reclamation area during 2015-2018 are obtained.PSInSAR technology is used to process the VV polarization mode data of the 21-scene Sentinel-1A dual-polarization SAR in Shenzhen's main reclamation areas,including Bao'an district,Futian district and Nanshan district,to obtain the surface deformation rate between 2015 and 2018.By analyzing the temporal deformation characteristics of main settlement areas,and combining the results of SBAS technology,the paper compares the spatial distribution and time series of the deformation velocity field.Finally,reliable results such as deformation range,deformation characteristics,average settlement rate and historical shape variables of time series in this area are obtained successfully.3.The causes of surface deformation in Shenzhen reclamation area are analyzed.Combined with the hydrogeological conditions and the local political and economic factors of the three regions,the corresponding deformation causes of surface deformation in different regions are analyzed.The causes of surface deformation in Baoan district are as follows: groundwater level drops due to engineering precipitation,the increase of large building clusters and primary and secondary consolidation in reclamation areas;The main reason for the ground elevation in Nanshan area is the elevation of groundwater level.It is caused by artificial fill(stone)in Qianhai area,which makes the groundwater level in this area be connected with atmospheric supply and surrounding seawater hydraulic power;Surface subsidence in Futian district is closely related to a large number of urban renewal and old city reconstruction projects in Shenzhen in recent years.Large-scale municipal engineering construction not only has an impact on its own ground level,but also affects the surrounding buildings.Besides,these Largescale urban renewal activities also affect Baoan district and Nanshan district.