InSAR measurements of surface deformation over permafrost on Fenghuoshan Mountains section, Qinghai-Tibet Plateau

Abstract

The permafrost development in the Qinghai-Tibet Engineering Corridor (QTEC) is affected by natural environment changes and human engineering activities. Human engineering activities may damage the permafrost growing environment, which in turn impact these engineering activities. Thus high spatial-temporal resolution monitoring over the QTEC in the permafrost region is very necessary. This paper presents a method for monitoring the frozen soil area using the intermittent coherence-based small baseline subset (ICSBAS). The method can improve the point density of the results and enhance the interpretability of deformation results by identifying the discontinuous coherent points according to the coherent value of time series. Using the periodic function that models the seasonal variation of permafrost, we separate the long wavelength atmospheric delay and establish an estimation model for the frozen soil deformation. Doing this can raise the monitoring accuracy and improve the understanding of the surface deformation of the frozen soil. In this study, we process 21 PALSAR data acquired by the Alos satellite with the proposed ICSBAS technique. The results show that the frozen soil far from the QTR in the study area experiences frost heave and thaw settlement (4.7 cm to 8.4 cm) alternatively, while the maximum settlement along the QTR reaches 12 cm. The interferomatric syntnetic aperture radar (In-SAR)-derived results are validated using the ground leveling data nearby the Beiluhe basin. The validation results show the InSAR results have good consistency with the leveling data in displacement rates as well as time series. We also find that the deformation in the permafrost area is correlated with temperature, human activities and topography. Based on the interfering degree of human engineering activities on the permafrost environment, we divide the QTEC along the Qinghai-Tibet Railway into engineering damage zone, transition zone and natural permafrost.