基于SAR影像的贡巴冰川末端冰湖年际变化监测及溃决规律分析

Monitoring of Interannual Variabilities and Outburst Regularities Analysis of Glacial Lakes at the End of Gongba Glacier Utilizing SAR Images

  • 摘要: 受全球气候变化的影响,近年来藏东南区域多数冰川退化加剧,冰湖的异动也更为频繁,冰湖溃决诱发洪水、涌浪、泥石流等山地灾害的风险激增。以多源时序合成孔径雷达(synthetic aperture radar,SAR)影像为数据源,从水体和非水体信号的强度差异出发,开展冰湖的分类方法研究,提出了一种基于时序SAR影像的强度标准化比值实施冰湖提取与动态监测的方法。为了验证方法的可行性,选取日本航天局的ALOS/PALSAR-1与欧空局的Sentinel-1A影像序列,针对位于贡巴冰川流域的典型实验区,在11 a的时间跨度上开展了冰湖动态提取和长时序变化分析。通过实验成功获取了贡巴冰川末端冰湖2007-2018年间的时空变化,进而发现近10 a间冰湖的体量呈高速增长的态势,这从侧面也印证了贡巴冰川消融加剧的现状。此外,2018年的新近监测结果表明,局部溃决涌道的扩张打破了冰湖固有的生存周期,甚至会诱发洪水和泥石流次生灾害的发生,有必要加强监测与防范。

     

    Abstract: Affected by global climate change, most glaciers in southeastern Tibet have deteriorated more and more frequently. The risk of mountain disasters, such as floods, surges and debris flows, has increased sharply in recent years. This paper implements a research on glacial lakes classification by using multi-source synthetic aperture radar (SAR) images. According to the statistical analysis of intensity difference between signals coming from water and non-water objects, a method of glacial lake extraction and dynamic monitoring based on the intensity standardization ratio of sequential SAR images is proposed. Within a typical experimental area in Gongba Glacier basin, the image series of ALOS/PALSAR-1 of Japan Space Agency and Sentinel-1A of European Space Agency are selected to carry out dynamic extraction of glacial lakes and long-term change analysis over 11 years'time, just for validation purpose. The temporal and spatial variations of glacial lakes at the end of Gongba Glacier from 2007 to 2018 are successfully obtained. And the further analysis finds out that the volume of glacial lakes increase rapidly in the past ten years. This evidence can also confirm the current situation of aggravated melting of Gongba Glacier. In addition, the recent monitoring results in 2018 show that the expansion of local burst gushes has broken the inherent life cycle of glacial lakes, and even trigger secondary disasters of floods and debris flows. It is necessary to strengthen monitoring and prevention.

     

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