Study On Debris Flow Characteristics In Temperate Glacier Area Of Pallon Tsangpo

Pallon Tsangpo basin is the main distribution area of marine glacier in China that is located in the special conditions of terrain and climate.Due to the complexity of geology and geomorphology,hydrology and climate and other natural environment,it becomes the most disaster types,the most dense distribution and the most highest frequency sections during the whole Sichuan-Tibet highway with resulting in debris flow disasters in the basin.Frequent occurrence of Debris flow activities seriously hinder the economic development in mountain areas in the West,even lead to ecological environment deteriorate in the area.In order to ensure the smooth flow of the Sichuan-Tibet Highway,as well as the Southeast of Tibet economy development and the smooth implementation of the Western development strategy,we on the basis of available information study deep on debris flow characteristics of Pallon Tsangpo Valley,in particular glacial debris flow.At last,we obtain the following results:1.Through investigating typical disaster worksites of debris flow in the research region,we interpret that the debris flow gully are distributed asymmetrically on both sides of the basin and more distributed in the valley with airborne and satellite data.Then according to whether there is glacier in debris flow gully,we divide debris flow into glacier type and rainfall type.Also,we summarize reference standards to identify them through the comparison between the characteristics of basin growth.Finally,we decide the type of debris flow of every gully.2. We simply calculate the runoff of rain type debris flow with distribution method. For glacial debris flow,according to the rainfall condition,there are three aspects:no rain in the basin,glacier area without rain,rain around in the basin.In debris flow prevention design, according to rainfall situation in the basin,we adopt the corresponding runoff formula to calculate;otherwise,it is best to use the maximum value to design in the case of rain all over the basin.Then,we make use of the most disadvantaged value to do sensitivity analysis so that we can ensure the sensitivity of debirs flow on effect parameters,and take special consideration in the study of prevention countermeasures of debris flow disaster.3.Parameters related to the glacier are different,They has the different effect of debris flow.Therefore.we firstly analyse the types of glacier that more cirque glaciers or hanging glaciers in the right bank,but more valley glaciers on the left bank,which is primarily associated with the location distributed and the direction towards to the sun of debris flow gully.Then,we respectively described effects of glacier styles on debris flow from three aspects that the formatedconditions of debris flow,the activity of debris flow and the severity of debris flow.In the end,we come to a conclusion:glacier’s slope is greater,more conducive to the glacier ablation;debris flow gully that break out frequently have basically developcirque glaciers or hanging glaciers,less valley glacier;it is not obvious that the relationship between glacier types and severity of debris flow,but once the gully which has larger growth of valley glacier occurs debris flow,its severity is inestimable and the possibility of blocking the river is very big.In short,we hope that important characteristics of debris flows in the study areacan provide some help for the railway,highway and other relevant departments in engineering survey and routing design in the future.