Topography Extraction And Surface Deformation Monitoring In Mayang Of Hunan Province Based On InSAR Technology

Since the birth of InSAR technology,it has been rapidly popularized in the research work of terrain extraction and surface deformation monitoring due to its high accuracy.However,it is also affected by factors such as orbital parameter errors,vegetation coverage,phase unwrapping errors,and atmospheric delay.The appearance of the short baseline set interference method(SBAS-InSAR)overcomes the phenomena of atmospheric delay effects and spatial and temporal loss to a certain degree.This research area is Mayang Miao Autonomous County(hereinafter referred to as Mayang County)in Hunan Province.No relevant researches have been carried out in this area so far.Therefore,the use of InSAR technology for research has achieved the following results:(1)By processing Sentinel-1 data covering the research area,good quality images are obtained,and the steps and parameters in the processing process are explored and experimented,which can provide data parameter reference for future radar interferometry work in the area.(2)Using InSAR technology to obtain DEM data in the study area,and using ASTER GDEM data as reference data to evaluate its accuracy,the extraction error value is between 0-783 m,the average error value is 47 m.And then the influencing factors of the extraction error are analyzed,in the study area due to the impact of vegetation coverage,the extraction accuracy is not ideal in areas with higher elevations.(3)Using the SBAS-InSAR technology,the deformation rate maps of the study area were obtained from April 2016 to September 2018.The analysis of the influencing factors of the deformation found that there was more deformation distribution within 1.5 km on both sides of the active structure.In addition,the elevation was in the 180-500 m area,on both sides of the river and within 300 m on both sides of the road,the south-east and north-west slopes have large deformation rates during flood seasons with large precipitation,and are prone to disasters.Care should be taken to prevent them.(4)During the monitoring of surface deformation in Mayang County,it was found that the surface deformation of county area is-15 mm to 28 mm in Mayang County is mainly resilience due to long-term stable building loads in the urban area.The areas with large deformation are mainly the newly constructed surrounding areas.And then industrial parks,Longchi Bridge and other places with obvious deformations were selected for deformation and analysis,and the effect of out-of-coherence on judging urban expansion was explained by comparing the two phase images.