雅鲁藏布江下游沿河段滑坡崩塌空间分布特征及其主控因素

The Spatial Distribution and Main Controlling Factors of Collapse-landslides Along the Downstream of Yalung Zangbo River

通过对雅鲁藏布江下游河谷地区的遥感影像解译和滑坡、崩塌点实地调查,得出研究区内滑坡崩塌总计454处,集中分布于帕隆藏布通麦至拉月曲汇口段、培龙沟至帕隆藏布入汇口段以及雅鲁藏布江干流大拐弯段。在此基础上,利用GIS技术对研究区滑坡崩塌分布与坡度、岩性、断层密度、构造隆升等因素的关系进行统计分析表明:(1)滑坡的坡度在30°-40°之间,崩塌的坡度在40°-50°之间最为发育,而两者均在片岩、片麻岩、花岗岩和大理岩中集中发育。超过70%的滑坡、崩塌分布在断层密度高的区域,且超60%的滑坡崩塌处于地壳隆升区。(2)滑坡崩塌发育的主控因素为强烈的构造隆升和高密度的断层。喜马拉雅造山带强烈的构造隆升使得地势陡峭,坡度大、势能大;雅鲁藏布江缝合带东段的高密度断层导致岩体破碎、稳定性差,在强降水或地震作用下易发生滑动。

Based on the remote sensing interpretation and field investigation of landslides and collapses in the downstream region of the Yarlung Zangbo River,454 landslides and collapses were counted in total,most of which distributed from tongmai to layuequ,peilonggou to Jiedong along the Parlong Zangbo River,and the great canyon section of the Yarlung Zangbo River.On this basis,the relationships between the landslide-collapse distribution and slope,lithology,fault density,tectonic uplift are statistically analyzed by using GIS technology.The results propose that:(1)30°-40°are the trigger slopes of landslides in the study area,collapses are most developed with the slopes of 40°-50°and the highest proportion of gneiss,schist,marble and granite in lithology.More than 70%of landslides and collapses are distributed in areas with high fault density,and more than 60%of landslides and collapses are developed in the tectonic uplift region.(2)The main controlling factors in landslide and collapse development are the active tectonic uplift and the high-density distribution of faults.Respectively,the Himalaya orogenic belt uplift creates the mass steep rocks with large slope and potential energy foundation;the development of high-density faults in eastern Yarlung-Zangbo suture zone induces bedrocks broken and instability,which are easily sliding under heavy precipitations or earthquakes.