西藏扎墨公路沿线泥石流的垂直地带性特征

Vertical Zonality Characteristics of Debris Flow Along Zhamo Highway in Tibet

[目的]研究扎墨公路沿线泥石流的垂直地带性分异特征,为泥石流灾害的安全预警和防治提供科学依据。[方法]以2009—2015年进行的多次野外调查为基础,通过成因分析与案例研究,探讨地带性因素对扎墨公路沿线泥石流的分布、成因类型以及泥石流体性质等方面的影响,总结泥石流的垂直地带性分异规律。[结果]扎墨公路以东西向延伸的岗日嘎布山为界分为南北两段,其中北段穿过5个垂直带谱,南段穿过8个垂直带谱。泥石流的分布密度与暴发频率随着海拔的降低呈现出低、高、低的特征;成因类型由冰面湖溃决型、冰川型、融水降雨型泥石流逐渐过渡到降雨型泥石流;泥石流流体性质从泥流、水石流、稀性泥石流、亚黏性泥石流、黏性泥石流逐渐过渡,容重依次增大。[结论]随着公路沿线垂直带由Ⅰ带降低到Ⅷ带,泥石流的分布、成因类型和流体性质,随之发生有规律的变化,地带性分异特征在南段更加显著。

[Objective]To study the vertical zonality characteritics of debris flow along Zhamo highway in Tibet in order to provide basis for pre-warming and control of debris flow disasters.[Methods]Based on the field surveys conducted during the period from 2009 to 2015,the influences of zonal factors on the distribution,genetic types and fluidic properties of debris flow along the Zhamo highway were discussed,and then the vertical zonality of debris flow were summarized by genetic analysis and case study.[Results]From south to north,Zhamo highway was divided into two sections by Mt.Gangrigabu,which passes through 5 vertical belts in the south and 8 vertical belts in the north.With the descending of altitude,the density and frequency of debris flows showed a low—high—low tendency.The genetic types gradually changed from debris flow induced by glacial lake outburst flood,glacial debris flow,meltwater-rainfall debris flow,into the rainfall debris flow.Correspondingly,the fluidic properties gradually changed from the mud flow to diluent debris flow,sub-viscous debris flow,and finally into viscous debris flow.[Conclusion]With the vertical belt along the highway descending from theⅠbelt to theⅧ belt,distributions of debris flow,genetic types and fluidicproperties changed regularly,particularly,the vertical zonality characteristics tend to be more conspicuous in the south section of the highway.