联合卫星SAR和地基SAR的海螺沟冰川动态变化及次生滑坡灾害监测

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

  • 摘要: 受全球气候变化的影响,近年来中国藏东南及横断山脉多数冰川物质持续亏损、运动速度减缓,导致泥石流、滑坡等灾害频发。为突破光学遥感受气候条件制约的瓶颈,联合卫星合成孔径雷达(synthetic aperture radar,SAR)和地基SAR两种技术手段,选取海螺沟冰川作为典型研究区域,开展时序监测分析。基于对近11 a间获取的38景PALSAR系列影像的像素偏移统计表明,海螺沟1号冰川粒雪盆和冰瀑布上沿区域整体运动最快,最大速度超过2 m/d;在海拔2 900~3 900 m的冰舌区,冰川运动趋缓,速度降至0.1~0.4 m/d;随着季节更替,海螺沟冰川运动速度呈周期性波动,积累区的夏冬两季差异为25%~35%,而冰舌段的差异则高达4倍。在年际变化方面,海螺沟1号冰川的运动速度平均减缓率为每年7.27%,消融区内减缓率高达每年15.57%。同时,使用像素偏移追踪和Stacking-InSAR(interferometric SAR)方法在海螺沟U型谷北坡探明了多处不稳定滑坡体,统计分析表明,此类滑坡运动与冰川消融具有强相关性,滑移速度于每年夏季达到峰值,2018年度最大滑移速度为南北向100 mm/d、东西向50 mm/d。进一步分析地基雷达的高频实时监测数据,确定该滑坡体的滑移速度在2018-07-09达到峰值(150 mm/d),并于随后失稳垮塌,详细展现了整个蠕变致灾过程。相关研究数据及监测结果可为冰冻圈及山地灾害研究提供参考。

     

    Abstract: 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.

     

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