Comparative Study Of Time-series InSAR Technology In Coastal And Land Deformation Monitoring

As an active surface deformation monitoring technology,synthetic aperture radar interferometry(InSAR)is widely used in coastal areas,especially in coastal urban areas with serious land subsidence,due to its advantages of not affected by cloud and rain,wide monitoring range and high precision.However,InSAR technology will suffer serious spatiotemporal incoherence,atmospheric disturbance and poor measurement accuracy in the mountainous area of Southwest China,which limits its application in geological disaster survey and high-precision monitoring.Since the completion and operation of the Three Gorges Dam,the frequency and risk of landslide disasters have increased due to the periodic regulation and change of water level in the reservoir area.In this paper,22 alos-1 images and 9 radarsat-2 images are used to monitor the landslides in Zigui section of the Three Gorges Reservoir area.The main contents and results are as follows:(1)The comparative analysis of InSAR Technology in land subsidence in coastal areas and landslides in inland areas is carried out.In terms of data,the accuracy of C-band SAR data is higher because of the wave length;In landslide deformation monitoring,C-band data is seriously incoherent,while L-band data has better coherence in landslide monitoring.From the technical point of view,land subsidence is usually monitored by PS-InSAR and SBAS-InSAR,which can achieve good results;The landslide deformation monitoring usually uses a combination of various technologies.In terms of application effect,land subsidence deformation monitoring has been applied in a large area,and the accuracy can reach mm level;The accuracy of landslide deformation monitoring varies greatly according to the actual situation.(2)IPTA-InSAR technology is applied to identify regional landslides.For alos-1 data,PS-InSAR technology is used to retrieve the average surface deformation information of Zigui section in the Three Gorges Reservoir area;For radarsat-2 data with small data set,SBAS-InSAR technology is used to retrieve the average surface deformation information.Combining the deformation information of the two datasets with optical remote sensing image,digital terrain model(DEM)and other data,the landslide disaster detection and recognition can be realized.In this study,20 landslides were found,including 16 known landslides,which proved the ability of InSAR Technology in landslide disaster identification.At the same time,the characteristics of different bands and different time series InSAR Technology in landslide identification and detection are preliminarily analyzed.(3)SBAS-InSAR technology is applied to monitor the key landslides in the study area.Aiming at the identified fanjiaping landslide,the deformation of alos-1 data is monitored by SBAS-InSAR.The deformation information of landslide is compared with the real-time GPS monitoring data,and the accuracy of InSAR Technology in monitoring landslide disaster is tested.The time and space variation characteristics of the landslide are analyzed,and the deformation history of the landslide during the monitoring period is restored.It is proved that the landslide conforms to the progressive failure characteristics.In addition,the relationship between the deformation characteristics of the time series of the landslide and the water level and rainfall in the reservoir area is analyzed,and it is concluded that the cumulative deformation of fanjiaping landslide is obviously affected by the rise and fall of the reservoir water level.In addition,five soil landslides and seven rock landslides are selected as examples to analyze the response relationship between soil landslides and rock landslides and reservoir water level and rainfall.