Study On The Method Of Multi-platform SAR Data Sets And MTInSAR Technique Based Ground Deformation Monitoring

Accompanying the development of InSAR techniques, an increasing number of Synthetic Aperture Radar(SAR) satellites have been and will be launched. It means that many regions have simultaneously been imaged or will simultaneously be imaged by different SAR sensors, and massive multi-platform(multi-sensor, multi-band, multi-track) SAR data sets have been accumulated. These multi-platform SAR data sets with different imaging parameters, such as azimuth and incidence angle, spatial and temporal resolution, orbit direction and wavelength, are complementary to each other in land motion monitoring to some degree, since they can show different characteristics in maximum detection gradient, degree of decorrelation, capability of noise rejection. However, the exsited InSAR techniques mainly concentrate on utilizing one kind of SAR image(from one kind of platform) to monitor ground deformation. Therefore, it is essential to study the methods that can combine multi-platform SAR data sets to estimate land deformation. This paper studied three kinds of multi-platform based MTInSAR techniques, which had then been tested and used to monitor the ground deformation of Cangzhou area. The main concusions of the study is as follows:(1) The principles of InSAR and DInSAR had been introduced, two MTInSAR techniques(PS and SBAS) were then presented, repectively;(2) The combination method(the first combination method), which based on the multi-platform SAR data sets and no horizontal ground deformation, was proposed. The approach is mainly based on the MTInSAR technique and the Same Name target point Pairs(SNPs) combination strategy. The combination strategy can enhance the spatial and temporal sampling rates of InSAR derived deformation solutions, which is essential, especially in uneven(spatially variable) and non-linear(temporally variable) ground movement detection;(3) The multi-platform SAR data sets and fixed horizontal deformation assumption based ground deformation monitoring method(the second combination method) was stuied. The ground deformation was first derived by individual platform SAR data set separately, the SNPs searching and weighted LS methods were employed to estimate the horizontal and vertical defroamtion subsequently. Comparing to the single-platform InSAR technique monitoring, this combination method has the advantage of retrieving 3 dimensions or “quasi 3 dimensions” ground deformation;(4) The SBAS and regularization based multi-platform InSAR ground deformation monitoring method(the third combination method) was studied and improved. In the third combination method, the weights of the DInSAR mesurements were introduced and the regularization matrix was modified by considering the quality ground deformation characteristic. The method can obtain 2 or 3 dimensions time-series ground deformation and it has the advantages of enhancing monitoring frequency and retrieving multidimensional land deformation;(5) A comparison between the three methods, which had been studied in this paper, had been made and some conclusons and suggestions had been given:(1)In the case that the ground horizontal deformation of the study area is relatively small, such as the underground water induced land deformation, the first combination method is suggested to be employed to obtain the ground deformation;(2)In the case that the ground horizontal deformation of the study area is relatively small, such as the underground water induced land deformation, the first combination method is suggested to be employed to obtain the ground deformation;(3)In the case that there are more than two kinds of SAR data sets in the study area, the third combination method is suggested to be utilized;(6) The above mentioned three combination methods had been utilized to study the ground deformation of Cangzhou area, the results shows that:(1) the two subsidence centers of the study area were Qing and Cang counties, which located at north-west and south-east of Cangzhou city respectively. The major subsidence velocity and cumulated subsidence in the study area during the monitoring period were-10 to-20 mm/yr and-40 to-160 mm, which account for 78% of the total MPs;(2)The deformation velocities of all the four subsidence centers, which were not located in urban area, reached up to-55 mm/yr. The subsidence of the four subsidence centers were nonlinear deformation and precipitation with groundwater depth were the mainly two factors that influenced the subsidence velocity;(3)The two major subsidence areas were the areas whoes water system were rich and the accumulated subsidence of Cangzhou city decreased as it away from the center of Cangzhou.