利用2016—2020年Sentinel-1数据监测与分析三峡库区树坪滑坡稳定性

  • 摘要: 由于不良地质条件和周期性蓄水等因素影响,中国三峡库区岸坡的稳定性问题一直备受关注。获取了覆盖树坪滑坡周围区域2016-03─2020-03的111景哨兵1号(Sentinel-1)数据,利用时间序列合成孔径雷达干涉测量技术(interferometric synthetic aperture radar,InSAR)对该数据集中的高相干点目标和分布式目标进行分析,获取实验区坡体变形。结果显示,实验区内有7处坡体处于活跃状态,最大变形速率达到70 mm/a。与树坪滑坡GPS形变观测值进行比较,验证了InSAR结果的有效性。通过对树坪和三门洞等典型滑坡的时序分析发现,库区水位和集中降雨是滑坡变形的主要影响因素,实验区内的治理工程有效减缓了变形趋势。与此同时,公路建设与植被耕种等人类活动引起了熊家岭村等出现地面沉降,需密切关注以防止出现安全隐患。所得结果证明时序InSAR技术可以有效识别和监测滑坡,为地质灾害风险普查以及防灾减灾治理成效评价提供技术支撑。

     

    Abstract:
      Objectives  Due to the impact of unfavorable geological conditions and periodic water level fluctuations, the stabilities of the bank slopes in the Three Gorges area have always been concerned.
      Methods  111 Sentinel-1 images covering the Shuping landslide and its surrounding area from March 2016 to March 2020 are obtained. Time-series interferometric synthetic aperture radar (InSAR) analysis method combing point-like targets and distributed scatters employed to obtain the slope displacement of our study area.
      Results  We identified 7 active slopes with a maximum displacement rate of 70 mm/a. Our InSAR results were validated by comparing measurements with two GPS stations installed on the Shuping landslide from 2016 to 2018. Time-series analysis indicated water level variations and concentrated rainfall are the main impact factors of slopes. Our study indicated landslide control projects will significantly decrease the slope displacement rates of landslides. The maximum displacement rate of the Shuping landslide decreased 70 mm/a after the cutting slope in 2014—2015. The displacement rates of the Sanmendong and the Zhoujiapo landslides also reduced from 0.8 mm/d to 0.2 mm/d due to the revetment works from 2018 to 2019. At the meantime, displacement in Xiongjialing Village induced by anthropogenic activities such as road construction and vegetation cultivation need to be monitored closely in case of developing into safety threats.
      Conclusions  Our results indicate that the time-series InSAR technology can effectively identify and monitor active slopes and provide technical support for geological hazard risk mapping and disaster prevention and mitigation.

     

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