雅鲁藏布江大峡谷则隆弄高位冰岩崩灾害链动力学特征

DYNAMIC CHARACTERISTICS OF THE ROCK-ICE AVALANCHE DISASTER CHAIN IN THE ZELONGNONG BASIN,YARLUNG ZANGBO RIVER CANYON REGION

雅鲁藏布江下游冰川分布广泛,曾发生多次高位冰岩崩事件,引发灾害链,如泥石流或碎屑流,危害巨大。本文通过野外现场调查,结合多时相卫星图像及无人机数据,以则隆弄沟为例,分析了高位灾害的地貌特征及运动动力学效应。研究表明:(1)则隆弄沟高位灾害垂向落差大,不同海拔区段微地貌形态各有差异,具有典型的垂直分带性,根据地貌展布特征及形态可划分为高陡冰蚀地形、弯曲型沟谷地形、堆积河谷地形,独特的地貌条件和地质环境使高位灾害与中低海拔地区有显著区别。(2)高位冰岩崩灾害链经历冰岩崩、碎屑流运动、堆积堵江、洪水溃决4个阶段,形成高位远程地质灾害链,运动过程中表现出复杂的动力学效应,包括冲击解体效应、散体成拱效应、动力侵蚀效应、碎屑堆积效应,为研究碎颗粒流动行为及动力学过程提供信息。(3)则隆弄冰舌处冰碛物富集,冰舌前缘及后缘分布有大量裂缝,随时间推移内部裂纹扩展累积,应力拱承载力下降而破坏致灾。未来在气候变化及强烈的构造活动影响下,雅鲁藏布江下游高位冰岩崩灾害风险极高,引发次生堵江-洪水灾害危害极大,应加强这类流域性灾害的预警及风险防范。

The glaciers downstream of the Yarlung Zangbo River are widely distributed,with frequent occurrences of rock-ice avalanches.These avalanches often lead to secondary disasters,such as debris flows or avalanches,causing significant damage.Through field investigations,combined with multi-phase remote sensing images and aerial photography,this study analyzes the geomorphic characteristics and dynamic effects of high-altitude disasters in the Zelongnong Basin.The research results reveal the following:Due to the significant vertical drop,the Zelongnong Basin exhibits typical vertical zonality.The distribution characteristics and morphology can be categorized into three geomorphic types:high and steep glacial micro-geomorphology,curved gully micro-geomorphology,and deposit micro-geomorphology.The progression of the rock-ice avalanche disaster chain can be divided into four stages:rock-ice avalanches,debris flows,river blocking,and flooding.Debris flows exhibit complex dynamic effects,primarily including impact disintegration,soil-rock mixture arching,dynamic erosion,and debris deposition.These aspects provide valuable information for studying the flow behavior and dynamic processes of particles.Moraine accumulation is concentrated at the ice tongue,with numerous cracks distributed at the front and rear edges of the ice tongue.Over time,internal cracks expand and accumulate,leading to a decrease in stress arch bearing capacity and subsequent damage.In the future,under the influence of climate change and strong tectonic activity,the risk of rock-ice avalanches in the downstream Yarlung Zangbo River is extremely high.Early warning systems and risk mitigation measures for basin disasters should be prioritized.