震后环境下单沟高含沙水流与泥石流相互演化规律是泥石流工程防治的关键问题。以茂县牟托沟泥石流为例,探讨了牟托沟泥石流物源补给和微地貌在高含沙水流与泥石流相互演化过程中的重要性。首先分析了牟托沟地形地貌特点;其次利用容重分析了牟托沟高含沙水流与泥石流相互演化特征;最后采用一次泥石流固体物质总量的形态调查法和阶梯-深潭微地貌效应分析方法分析了高含沙水流与泥石流相互演化机理。研究表明:(1)牟托沟泥石流起动模式为冲蚀→冲沟→堵塞→溃决→泥石流的模式;(2)在弃渣和崩坡积物的影响下牟托沟易形成阶梯-深潭微地貌;(3)高含沙水流与泥石流的相互演化和一次泥石流固体物质总量关系密切。

The transition of hyper-concentrated flow and debris flow after earthquake is the key problem involved in debris flow engineering control.Based on the analysis of debris flow in Moutuo Gully,this paper studies the importance of source supplement and micro-topography in the transition of hyper-concentrated flow and debris flow.The terrain and landform are analyzed firstly;secondly,the density is used to analyze the transition character between hyper-concentrated flow and turbulent debris flow;and finally,landscape step-pool effect method and investigation method are applied to study the transition process and mechanisms. The result shows that(1)the initiation model of debris flows in Motuo Gully includes surface erosion,gully erosion,blocking,outburst and debris flow;(2)the formation of microtopography(step-pool)is resulted from waste slag and collapse or landslide;(3)the transition of hyper-concentrated flow and debris flow is closely related with the solid volume in one surge.