Monitoring Dynamics of Hailuogou Glacier and the Secondary Landslide Disasters Based on Combination of Satellite SAR and Ground-Based SAR

Due to the influence of global climate change, most glaciers in southeastern Tibet and Hengduan Mountains in recent years have been losing weight, deteriorating and thinning, which has caused the variation of glacier movement characteristics, resulting in frequent disasters such as debris flows and landslides. In order to break through the bottleneck of optical remote sensing restricted by climatic conditions, this paper combines satellite and ground-based synthetic aperture radar (SAR) technology and selects Hailuogou Glacier (HLG) basin as a typical research area to carry out time series monitoring and analysis. Firstly, by using 38 SAR images acquired by PALSAR-1/2 satellites from 2007 to 2018, the temporal and spatial variations and local surface displacements of HLG in Gongga Mountain are monitored by using the pixel offset tracking (POT) method. The average velocity of HLG No.1 is slowed down by 7.27% per year in recent years, and the slow-down rate reaches 15.57% per year in the ablation areas. At the same time, several unstable landslides are detected by POT and Stacking-InSAR methods at the moraine embankment on the side of the glacier. Statistical analysis confirms that the movement of such landslides is strongly correlated with the melting of the glacier. The sliding speed reaches its peak in summer every year. The maximum sliding speed in 2018 was 100 mm/d in the north-south direction and 50 mm/d in the east-west direction. Subsequently, by utilization of the high-frequency real-time monitoring data of ground-based radar, it is further determined that the sliding speed reaches its peak value of 150 mm/d on July 9, 2018, and abnormal fluctuations occur with the subsequent collapse, which shows in detail the whole process of landslide creep to result in disasters. Relevant research data and the monitoring results can provide a reference for the study of the cryosphere and mountain hazards.