Susceptibility Assessment Of Debris Flows And Prediction Of Gully Development In The Upper Reaches Of Min River

The upper reaches of Min River were selected as the research area in the paper.The main development characteristic of the debris flow is revealed by analyzing the geological environment.Some suitability evaluation factors are selected on this basis and evaluated the regional debris flow susceptibly in information method and predict debris flow gully development in geomorphic information method.The main conclusions of the paper are as follows:(1)Firstly,based on the environment analysis of the debris flow in the upper reaches of Min River,developmental characteristics were discussed from 3 aspects(including distribution,basin form and provenance).As the results show: the debris flow were presented in space with the strip shape along the river,major fault,alpine gorges with concentrated distribution.The integrity coefficients of gullies were small.There is negative correlation among longitudinal river slope,the gully main length and the basin area.The area is distributed 3 types of including landslide accumulation,instability and slope erosion.(2)Secondly,according to the discussion of debris flow disaster factors,the formation conditions of debris flow are summarized.Debris flow disaster occupies a large area in the following areas: small undulating mountain area(relief amplitude: 200~500m),marl and shale,phyletic with crystalline limestone of Triassic and Silurian,major faults,20 degrees to 40 degrees slope,woodland and bare land of 0.4 to 0.75 vegetation index.The analysis in correlation test to disaster causing factors shows that intensity factor has a great influence on slope,topographic relief,lithology,vegetation,population density and land use factors.The results of evaluation have certain engineering guidance significance in the postion of rataining dam.(3)Thirdly,based on the results of the correlation factor analysis,selecting of slope,lithology 9 elements as debris flow susceptibility evaluation factors,applying information model,the contribution of each factor to the occurrence of debris flow is analyzed.The results show that rainfall,slope and vegetation coverage provide more information for the occurrence of debris flow,In the sparsely populated arid valley and the lower steep slope,it is a high incidence area of debris flow,especially in the valley with source and distribution of slope erosion of Maoxian to Wenchuan to Lixian Country The low prone areas are mainly distributed in the high clear water areas,mostly covered by ice sheets,and less debris flow disasters.The high prone areas are mainly located in the plateau with low relief and the lower valley.The middle prone areas are located in both of their transition region.(4)Finally,draw on the calculation of geomorphic information entropy,the development trend of gully in the basin is discussed.The results indicate the debris flow of study area is mainly in the stage of the evolution of the juvenile valley.The valley is strongly eroded and the surface is undulating,which provides sufficient dynamic conditions for the formation of debris flow.There are also a number of debris flow gullies in the mature period,the erosion intensity is moderate,and the loose materials begin to accumulate.The number of debris flow in the elderly is less and the grooves are stable.