Research On Ground Deformation Monitoring In Kunming Dam Area Based On Spaceborne SAR Data

Based on ENVISAT,ALOS and Sentinel-1A SAR images,SBAS-In SAR method was used to extract the Kunming surface deformation information from 2003 to 2019.Secondly,the two-dimensional cumulative deformation was estimated with the Sentinel-1A images.And then this paper discussed the present situation of non-uniform deformation of Kunming based on the information entropy theory.Finally,the relationship between groundwater activity and surface deformation was briefly discussed,and In SAR technology has been expanded from time and space in Kunming monitoring application.The main research work of this paper includes:(1)The deformation evolution characteristics of long-time series In SAR in Kunming were discussed.In view of the lack of long-term In SAR monitoring,multi-source SAR images were used to extract surface deformation in the study area from 2003?2019.By comparing and analyzing the differences of the coherence coefficient graphs obtained in different monitoring periods,and the deformation evolution characteristics generated by the change of time in the study area were systematically revealed,so as to achieve the purpose of long-term In SAR monitoring in the main urban area of Kunming.Finally,the reliability of the SBAS results was verified by Sentinel-1A ascending and descending images.(2)The MSBAS model with conditional constraints was studied to solve the two-dimensional time-series deformation.According to the indirect method,the 3D deformation rate was estimated,in which the maximum vertical subsidence rate is about 75mm/a,the maximum east-west subsidence rate is 77mm/a.And then we use the MSBAS model of Tiknonov regularization and phase variance weighting constraint to solve the 2D cumulative deformation.Tiknonov regularization solves the rank defect problem and improves the stability of the model.The phase variance weighting improves the accuracy of the model.On this basis,the 2D evolution characteristics of eight feature points are quantitatively analyzed,and it found that:the two-dimensional deformation process of feature points P1?P7 has a significant linear relationship with time,and the maximum vertical cumulative deformation of all feature points is 25 mm,and the maximum east-west cumulative deformation is 8mm.(3)The information entropy is used to evaluate the present situation of uneven deformation of Kunming.In SBAS monitoring results,on the basis of reference to risk hierarchy classifying deformation rate in the study area,and then statistical area percentage of different deformation conditions,and to calculate the ground surface deformation information entropy,finally the study area are discussed from the overall and local surface uneven deformation situation,from all the towns of time space and reveals the differences and changes in the surface characteristics of the information entropy distribution,to achieve the quantitative analysis of the present status of the uneven deformation.The results show that the non-uniform deformation is serious in Kunming,Xiaobanqiao township in Guandu district and Majie,Fuhai and Qianwei township in Xishan district are still in the middle entropy area,which need to be monitored in the later period.(4)The relationship between groundwater activities and surface deformation at two monitoring points in Kunming city was briefly analyzed.From 2007 to 2010,there was a strong correlation between surface deformation at points S1 and S2 and groundwater.