Study On The Regularity Of Debris Flow Distribution And Influence Factors In Bailong River Basin

Debris flow disasters occur frequently in the study area and widely distributed, its great destructive power, with the economic development of the area, human activity is increasing; the relative concentration of population and the economy makes regional vulnerability increases, and thus lead to debris flows potential sub-first constant increase. Debris flow research is not perfect, it has remained mostly in the qualitative analysis stage; relatively lag, so the study is significant debris flow.Firstly, on the basis of the analysis of the debris flow disaster field investigations in the area and data compilation, using statistical and spatial analysis of GIS, the study area since1960, the number of debris flow, size and loss analysis, reveal the time and the spatial distribution characteristics.Secondly, according to the previous work experience and relevant literature, but also, as far as possible, to the applicability of the area, selected made-depth analysis of the geological conditions, topography, hydrology and human activities conditions and other factors, which focuses on analysis of the relationship between the factor of formation lithology, geological structure, slope, elevation, vegetation index, land-use and the distribution of debris flows, as well as the triggering factor of the relationship between rainfall and debris flow, and to explore the main factors in each type of conditions mudslides activity.Thirdly, AHP method to build the hierarchy model of debris flow impact factor in study area, and multiple comparisons in each layer of the impact factor, get any two influencing factors relative weights, and each level under the judgment matrix. The maximum eigenvalue of judgment matrix, it corresponds to the feature vector further relative to the corresponding level impact factor relative importance of the impact factor.Through this analysis, it shows that the principle character of the time and the spatial distribution of debris flow in the study area and get the spatial distribution map of debris flow disaster, and then applied the overlapping functions of the GIS software and Spatial Analyst, statistical analysis of each factor, the result of the spatial relationships of each impact factor with the existing debris flows, and reflects the influence of the different lithology, different levels of slope, elevation with the debris flow. According to this results the debris flows are mainly distributed in the phylite, slate and limestone of the Devonian, Silurian, and15°-35°slope and altitude within the range of1000-1500m; mudslides distribution in the0.2-0.3range of the vegetation index and it most concentrated in Mountain and dry land. Finally, according to the AHP method obtained the results that the formation lithology> rainstorm> slope> geological structure>NDVI> elevation> the variation coefficient of annual rainfall> heavy rain> Land Use> monthly precipitation> annual precipitation, so we can see the formation rock and heavy rainfall are the main factors of debris flows. More consistent with the results obtained by the actual investigation, this conclusion can be provide the basis for selected to the risk assessment factors in which the latter research of debris flow disaster.