The distribution characteristics of debris flow along the Luhuo-Daofu section of Xianshuihe fault, west Sichuan Province

The Debris flow in Luhuo-Daofu section is linearly distributed along the Xianshuihe fault.It is mainly medium and high frequency, transitional and diluted debris flow.In the fault, the rock mass is broken, the secondary structure is developed with strong activity, so that the main riverbed is stepped, which provides potential energy transformation, material supply and hydraulic transport conditions for the development of debris flow disaster.Debris flow gullies (K_sn about 140 m^0.9) are distributed at the high river steepness indices of the trunk river (K_sn about 66 m^0.9).Moreover, debris flow gullies on the middle and lower reaches of the river and the trunk river in which they enter are more consistent in the trend of the river steepness indices.Wilcoxon test shows that the slope (26.5°), excess height (13.3 m) and peak ground acceleration of debris flow gullies on the northeast of the Xianshuihe fault are significantly higher than those on the southwest.Compared with debris flow gullies on the northeast of the Xianshuihe fault, the lithology of debris flow gullies on the southwest side are softer, and the topographic wetness index are larger.The principal component analysis indicates that the geology and geomorphology of debris flow gullies on the northeast side are relatively similar, mainly in steep terrain, and the geomorphology of debris flow gullies on the southwest side are more complex due to the influence of lithology and hydrological transportation capacity.The systematic understanding of debris flow gullies along the Luhuo-Daofu section can provide a reference for the prevention and control of debris flow disasters on the G317 Highway.