西藏天摩沟泥石流物源演变特征

天摩沟是西藏东南部典型的泥石流沟,分别于2007年、2010年和2018年暴发泥石流灾害,对当地居民和川藏公路造成多次危害.通过多期次遥感解译、现场调查、现场观测等手段确定历次泥石流事件前后物源分布和类型,运用GIS统计和剖面测绘,对比不同时期该泥石流沟物源面积平面和剖面上的变化,研究该沟物源的动态演变.天摩沟泥石流物...

Characteristics of debris flow source evolution in Tianmo Gully,Tibet

The Tianmo Gully debris flow in southeastern Tibet is a typical one, which broke out frequently in 2007, 2010 and 2018, causing harm to local residents and the Sichuan-Tibet highway for many times. The source materials distribution and types before and after debris flow events were drawn by means of multi-stage remote sensing interpretation, field investigation and field observation. GIS statistics and profile mapping were used to compare the changes of debris flow source materials area in plane and profile in different periods in the gully for the study of the dynamic evolution of the source materials. The source materials types of debris flow in Tianmo Gully are mainly moraine type, collapse type and erosion type. On the plane, moraine type source materials has the largest area, collapse type source materials is the most concentrated, and erosion type source materials extend the longest distance. On the profile, the source materials of the main channel varies most actively from 13° to 23°, among which, 17° to 23° is the starting site of debris flow erosion type, and 13° to 17° is the most intense site of debris flow erosion. The dynamic evolution of the source materials in Tianmo Gully is characterized by the "convergence and rapid melting" effect of avalanche accumulations year by year, and the instability of loose materials at the bottom and both sides of the channel. The avalanche accumulates in the main gully and extends downstream 1800 m from October to June of the next year. From July to September, the avalanche deposits are rapidly melted, releasing a large number of loose materials bound in the avalanche deposits and making the runoff in the gully increase sharply. The surge of runoff erodes the old moraines on both sides of the main ditch and converts them into debris flow sources. Research on the provenance evolution characteristics of debris flow in Tianmo Gully can reveal the reasons for the frequent occurrence of debris flow in Palongzangpo Basin, and provide reference for the early warning and disaster prevention and mitigation of debris flow in this region.