| Under the background of global warming,it is important to monitor the spatial distribution of island permafrost along the Bei’an to Heihe Expressway and furtherly obtain the deformation information of permafrost.Meanwhile,there is a great significance to explore the seasonal variation of island permafrost for the protection of infrastructure,the prevention of geological disasters,the stability of the system development and the exploration of regional hydrothermal conditions.In this paper,the Sentinel-1A satellite data is used to study the island permafrost along the Bei’an to Heihe Expressway.Firstly,the two-track technique of D-InSAR is used to calculate the surface deformation in the island frozen soil.It is proved that the applicability of Sentinel-1A satellite data in study area.Secondly,the relationship between natural elements and permafrost in the distribution of permafrost is analyzed.The main contents are as follows:(1)When roadbed subsidence has occurred,island permafrost has been degraded and landslides have happened frequently.It is significant to monitor the process of deformation in island permafrost region.The synthetic aperture radar differential interferometry is a feasible method to estimate the terrain stability of permafrost.The vertical deformation of the surface seasons is studied by using 12-day short-term Sentinel-1A satellite images.D-InSAR technique is used to extract the distribution of permafrost.The results show that the application prospect of Sentinel-1A in permafrost is proved by comparing the results of the regional deformation zone with the measured results.(2)The seasonal variation of permafrost in the permafrost region obtained from the two pairs of interference is taken as the experimental data.The results show that the seasonal variation of permafrost is subsided by summer for the fall of the frost heave in the autumn,in which the sinking occurred in June,the maximum sinking was 58.87 mm,and the frost heave in September increased from the southeast to the northwest,and the maximum ascending was 19.6mm.At the same time,The area of the subsidence area is mainly in the northwest-southeast direction,accounting for 41.32% of the total area.The rising surface accounts for 10.22% of the total area,located in the upper reaches of the central river area.(3)Combined with the deformation of study area,the soil moisture content,temperature,and vegetation trend of natural elements in the study area were analyzed.The relationship between surface deformation degradation and meteorological,soil water content and vegetation degradation in frozen soil area is discussed,which provides scientific basis for ecological management and protection of permafrost in alpine region under the background of ecological degradation.The results show that the active layer thickness of the permafrost is 1.8m.the temperature is over 0℃ at the formation depth of 2m in the summer of 2010.it is inferred that the frozen soil layer is thinner and appears after vegetation degradation.while the temperature is below 0℃,the active layer thickness has been restored thickness,and this time the vegetation has begun to recover.Due to the recurrence of frozen soil degradation,vegetation degradation after the ground temperature showed a great change in curvature.The variability of permafrost was positively correlated with soil water content,R2 was 0.2613,and the significance level was P <0.05.There was a positive correlation between the deformation and temperature,and the linearity of goodness R2 was 0.36,and the significance was P <0.05.The average subsidence was 23.88℃from July 15 to 27,2015,and the average subsidence was 33 mm.At the same time,the average settlement of permafrost was 11 mm.The average temperature from the beginning of June is 0.85℃ higher than at the ending of June,but the surface subsidence is higher than 3mm,indicating that there is a seasonal change in temperature and permafrost a certain lag. |
