InSAR Technology Is Applied To The Research On Dynamic Process Detection Of Debris Flow Tracks In The Dabaini River Valley

Debris flow is a major natural disaster that endangers the safety of human life and property,especially in areas with rugged terrain and valleys.Whenever debris flow disasters occur,a large amount of loose materials such as mud,sand and stones are entrained by rain water sources,which is fierce and causes serious damage to the local ecological environment.In order to ensure the safety of people's property,it is an unshirkable responsibility for surveying and mapping workers to obtain the characteristics and traces of debris flow in areas with debris flow disasters.At present,traditional monitoring methods,such as GPS and leveling,are unable to monitor large-scale surface deformation of river basins due to heavy workload,low safety,time-consuming and laborious factors.In recent years,In SAR technology has developed rapidly to obtain surface deformation information in urban and mountainous areas.Compared with traditional methods to obtain surface deformation information in debris flow areas,In SAR technology,as microwave remote sensing,has incomparable advantages such as high security and wide range,which makes up for many problems encountered by traditional monitoring methods.Dongchuan District is a typical debris flow-prone area in China.In this paper,a typical debris flow valley-Dabanni River Basin in Dongchuan District is taken as the study area,and SAR images are processed and analyzed by using ENVI SARscape platform,Arc GIS software and Sentinel-1 data,supplemented by SRTM 30-meter precision DEM provided by NASA and high-definition image data provided by Google Earth.The main work is as follows:The working principle of SAR satellite is described in detail,including the main SAR data products and SAR data processing software at present,and the principle and comparison of two time-series In SAR technologies mainly used in this paper.(2)The terrain visibility of SAR data of ascending and descending orbit in Dabanni River Basin is studied,and the range of good visibility and geometric distortion of ascending and descending orbit images under different orbits and different incident angles is analyzed.The results show that due to the large incident angle of the orbit raising mode,the good visible area is concentrated in the southeast of the study area;The incidence angle of the descent mode is small,and the area with good visibility accounts for a higher proportion,which is distributed in the northwest side,but the distortion area is complex and the terrain expression ability is poor.Combining the deformation results of the ascending orbit data with the deformation results of descending orbit can eliminate the influence of geometric distortion of SAR images to the greatest extent.(3)Using 15 images of the lift rail in 2018 and 16 images of the lift rail in 2019,the deformation information of the surface in the radar line of sight in the study area between May and November in 2018 and 2019 was obtained by using the method of combining PS technology with SBAS technology.The results show that the deformation characteristics of the study area expressed by the results of rail lifting and rail lowering are roughly the same: the upstream rises in a large scale,and large-scale settlement is observed on both slopes;The absolute value of deformation in radar line-of-sight is only about 30 mm,which can not express the true surface deformation caused by debris flow.(4)The 3D solution algorithm ignoring N-S deformation component is used to decompose the one-dimensional deformation of radar line of sight into two-dimensional deformation field composed of U-D direction and E-W direction,and the two-dimensional deformation field is analyzed.The results show that the peak values of the decomposed deformation in U-D direction and E-W direction are above200 mm,which can directly reflect the real deformation of the surface compared with the deformation information in LOS direction.Two-dimensional deformation sites in the two time periods have the same characteristics,which are the deformation characteristics that landslides on both sides move to the middle river section,and the accumulation area expands outward in a fan shape.(5)Processing the U-D deformation information,classifying the subsidence areas according to the deformation,obtaining the area and debris flow rate of different types of subsidence areas in 2018 and 2019,and analyzing and evaluating the debris flow sites in Dabanni River Basin in the past two years with the two indicators of area and debris flow rate.The results show that in 2019,compared with 2018,the area of debris flow and debris flow have increased,but the proportion of small gradient settlement area and the proportion of slight debris flow disaster area have increased greatly.(6)The causes of debris flow change are discussed from natural factors and human factors,in which longitudinal gradient of gully bed and provenance are the main factors,and human activities and other secondary factors and main factors jointly lead to debris flow change.