Map and Quantify the Ground Deformation Around Salt Lake in Hoh Xil, Qinghai-Tibet Plateau Using Time-Series InSAR From 2006 to 2018

After the bursting of the Zhuonai Lake in Hoh Xil, Qinghai-Tibet Plateau, in 2011, the water area and level of the Salt Lake increased rapidly. The lake area expanding would accelerate the melting of permafrost and contribute to many severe environmental issues, including the surface deformation around the lake. In this article, we retrieve the deformation of the permafrost area around the Salt lake using the time-series synthetic aperture radar (SAR) interferometry (InSAR) method with ENVISAT and Sentinel-1A images from October 2006 to December 2018. In order to get more measurement points, the distributed scatterers were utilized. Moreover, a deformation model combining two components, long-term linear deformation related with temperature, was adopted in the InSAR processing. The experimental results show that before the outburst of the Zhuonai Lake, the ground deformation was not obvious with the mean deformation rate of -5 to 5 mm/year from the ENVISAT results. From 2014 to 2018, the ground deformation around the Salt Lake gradually increased with the maximum deformation rate over -25 mm/year. The water area and the water level of Salt Lake were extracted based on the SAR amplitude images and Cryosat-2 radar altimeter data, showing a rapid increasing trend after 2017. The time-series displacement in the south of lake shows a high correlation with the lake level history. This study clearly illustrate that time-series InSAR could provide valuable information for monitoring potential hazards in permafrost region.