Land Subsidence And Landslide Monitoring Based On Spaceborne InSAR

Deformation monitoring and analysis of surface deformation is the key basis for safety assessment and prediction of geological hazards such as urban land subsidence,landslide and earthquake.China is a country with many geological disasters,the land subsidence of cities,landslides in mountainous areas and other geological disasters have been seriously affecting people's lives and property security and urban development and construction.It is of great significance for people's life and property safety and urban development to carry out large area surface deformation monitoring in the potential disaster areas of southwest China,and to carry out safety analysis and prediction according to information such as deformation information of monitoring objects and influence factors of deformation,which can effectively avoid or eliminate disaster losses.At present,traditional surface deformation monitoring methods(such as level measurement,GNSS,etc.)are limited by low spatial resolution,operational safety and high cost factors,which can not achieve large space scale and high spatial resolution of surface deformation monitoring and analysis.In recent years,interferometry synthetic aperture rader technology has been well mapped and geographically staffed by its ability to accurately obtain small surface deformation,It has been widely used in the research and application of large range detection and high precision monitoring of disasters.Compared with the traditional monitoring method of point-by-point observation,InSAR technology has the advantages of non-contact,all-weather,full-time,large scale and high spatiotemporal resolution,which overcomes the shortcomings of traditional monitoring methods,but the InSAR technology is affected by the spatial baseline mismatch,atmospheric delay and other factors to cause its own limitations.At the same time,the topography of southwest mountainous area is large,the vegetation cover is dense,which makes SAR image have many shadows and overlay and the atmospheric effect is more serious,so that InSAR technology still has many problems that need to be studied deeply in the aspect of disaster detection and high precision monitoring.In view of the above problems,the main research contents and contributions of this paper are as follows:(1)This paper systematically expounds the basic theoretical contents of InSAR technology,including the imaging principle and imaging characteristics of spaceborne InSAR technology,the principle of InSAR technology altimetry,the principle of technical deformation monitoring(differential InSAR,D-InSAR,error analysis of Spaceborne InSAR technology and introduction of common InSAR technology.(2)This paper systematically expounds the application and analysis of InSAR technology.Aiming at the problem of urban land subsidence in Kunming area,this paper uses 32 ascending sentinel-la TOPS SAR image and 32 descending sentinel-1A TOPS SAR image to obtain the information of Kunming surface subsidence in 2014-2017 years based on short baseline set technology.Combined with urban construction data,geological and hydrological data and meteorological data,the cause of formation of Kunming settlement area is comprehensively analyzed.The results showed that the spatial characteristics of surface subsidence in Kunming were not uniform,the Xishan district and Guandu district were prone to subsidence,the most serious of which was located in the subsidence area of Kunming new Luosiwan international trade city,and the accumulated subsidence reached-117.7mm.Ground subsidence is caused by soil deformation caused by metro construction and construction of large buildings and commercial districts.Groundwater extraction leads to the decline of groundwater level and ground subsidence induced by consolidation of quaternary soil.The abundant rainfall from June to November effectively complements the groundwater in Kunming,making the ground subsidence present obvious seasonal nonlinear subsidence with the rainfall.(3)This paper uses the 20 ascending rail sentinel-1A TOPS SAR image obtained during the period from November 24,2015 to February 22,2017 and the 20 descending rail sentinel-la TOPS SAR image obtained from December 8,2015 to March 8,2017,The landslide of the slope on both sides of the upstream reservoir area of the midstream hydropower station in the middle reaches of Jinsha River is detected respectively,and because of the complicated topography,the SAR position of the single track is completely detected.Through the comparison and combination of two SAR images in different orbital directions of lifting rails,it is found that the landslide areas detected by different orbits have the same area and different regions.At the same time,compared with the landslide detected by GPS,it is found that the landslide area detected by the lifting rail can completely cover the known landslide detected by GPs,and the landslide found by GPS technology can be found in the landslide area detected by the lifting rail.In addition,in order to verify the application of InSAR technology in landslide,this paper makes a quantitative comparative analysis of Baiya landslide with obvious deformation.Firstly,the deformation of radar eye view monitored by lifting rail is projected to the direction of slope,which ensures that the deformation amount with GPS monitoring is compared and verified in the same direction.The results show that the deformation trend of the monitoring deformation data of the two is roughly the same and has certain correlation,but there is a certain deviation in the deformation value.