| The western mountainous area is the region with the most abundant hydraulic resources in China.And a large number of hydropower stations have been built.It is also the region with the most frequent occurrence of landslide geological disasters in China.The construction of the dam will affect the stability of the slope in the reservoir area,and the deformation of the landslide in the reservoir area also threaten the safe operation of the dam.So the detection and analysis of the landslide deformation in the reservoir area need to be strengthened.The traditional deformation detection method has low observation efficiency and is not suitable for large-scale detection.The synthetic aperture radar interferometry(InSAR)technology has the ability to detect the surface deformation with all-weather,all-day,wide range and high precision,so it has unique advantages in the detection and analysis of landslide deformation in the reservoir area.In the process of deformation detection,de-coherence effect is an important factor affecting deformation detection.In terms of the association analysis of deformation,how to establish the relationship between deformation and factor like precipitation and find out the change law of deformation is the key to the monitoring and warning of the later stage of landslide in the reservoir area.The time-series InSAR technique can be used to monitor the deformation of the reservoir area along a long time,and the deformation time series can also be used to analyze its change rules.And the small baseline subsets(SBAS)InSAR technology is better to monitor the reservoir deformation information because of its multiple master images strategy that will generate better interferograms with high coherence.However,for the special topography of dam reservoir area,how to accurately and comprehensively obtain the deformation information of the landslide in the reservoir area,how to weaken the influence of errors in data processing,and how to determine the main factors affecting the change of the deformation rate of the landslide in the reservoir area are problems to be solved in the monitoring and application of time series InSAR technology in the reservoir area.In view of the above problems,this article selected Jinping first-class hydropower station reservoir area in Sichuan province as the experimental area,using SBAS-InSAR technique to study the reservoir deformation,the main contents are as follows:(1)Sentinel-1,PALSAR-1,and PALSAR-2 data were processed using the SBAS technique,and the annual mean deformation rate maps in line-of-sight(LOS)at different time periods and under different data sets were obtained.Aiming at the problem of geometric distortion in canyon topography,a method combining ascending and descending data results to detect the deformation of reservoir area is proposed,and the reliability of the deformation results is verified by cross comparison and analysis of the deformation results in the slope direction;(2)The influence of window size parameters in the unwrapping process of the StaMPS-SBAS method on the deformation extraction results is analyzed,and an index for evaluating the unwrapping accuracy of targets with high coherence is proposed based on the principle of standard SBAS-InSAR.Taking the actual landslide as an example,the consistency between the entanglement precision index and the deformation extraction result was verified,and the optimal window size parameters were set according to the index to accurately obtain the deformation information of the experimental area;(3)Based on the analysis of typical landslides,the trend and characteristics of the deformation rate at the point on the landslide are obtained by fitting and decomposition.Combined with the information of precipitation,the change of reservoir water level and the historical deformation,the correlation analysis was carried out on the deformation rate change of the landslide in Jinping reservoir area,and the main factors affecting the deformation rate change were determined. |
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