Research on InSAR Surface Deformation and Soil Hydrothermal Process in Permafrost

Surface deformation is an important feature reflecting the freeze-thaw process of active layer. To study the correlation between surface deformation and active layer hydrothermal processes, SBAS-InSAR technique was used to continuously monitor the surface deformation in the permafrost area of Yeniugou in Qilian Mountains in recent 5a, and the relationship between surface deformation and soil hydrothermal process was studied based on field observation data. The results indicate that the surface deformation caused by freeze-thaw process and hydraulic erosion is the most significant, and the surface deformation exhibits obvious seasonal characteristics. The cumulative surface deformation caused by freeze-thaw process is relatively small, and the interannual amplitude of frost heave and melt subsidence is about 10～20 mm; The cumulative surface deformation caused by hydraulic erosion is relatively large, with an interannual surface deformation exceeding 50 mm. Field observation data shows a slight downward trend in soil temperature in the active layer, with an increase in depth and duration of the negative temperature isotherm, and a gradual advance in the freezing front intersection date. The surface deformation has a good correlation with soil temperature and soil moisture, in areas where soil moisture enriched, the correlation is stronger, with correlation coefficients of −0.522 and −0.415 (P＜0.001), respectively. The changes in soil moisture content in soil moisture rich areas also have a more significant impact on the amplitude of surface frost heave and thaw settlement, and there is a good linear relationship. This article quantitatively describes the relationship between surface deformation of active layers and soil hydrothermal processes, which has reference significance for monitoring and studying the freeze-thaw parameters of large-scale active layers.