Hazard Assessment On Rainstorm Induced Debris Flows In Milling-Jiacha County Along Yarlung Zangbo River

Debris flow such a sudden natured disaster phenomenon which is a series continuous flow between block movement as landslide, rock-fall and sediment-laden flow .It has become a major kind of disaster with ferocious and sudden characteristics which threaten the economy contraction and transportation in mountain area. It is so necessary to reinforce the research and assessment to the great hazard and threatening of debris flows which threaten the towns in china because a huge of people are under the threat of debris, potential significant casualties and economic loss would caused and city functions would damaged to reduce the loss to a minimum .The most important duty which for organize and implement the mitigation and disaster prevention engineering scientificly and rationally is disaster risk assessment which risk a basic recognization and assessment to the possibility,threatening hazard range and harmful levels.So,the activities and development trends can be accurately and quickly responsed by the risk assessment of debris flow which has become a very important non-engineering measure of debris flow prevention.Based on the Yarlung Zangbo River Millington– Jiacha county section of the field investigation, analysis of the geological setting of the region, by analyzing the characteristics of a typical valley debris flow, induced conditions, calculate the velocity of debris flow, debris flow out of the first volume of traffic and so on, and then AHP for debris flow hazard assessment. In this paper, two indicators to calculate the risk of debris flow. Indicators of the first layer of topography, source conditions, causal factors and the amount of debris out. Under the four sub-ten second-level indicators index, which is a debris flow are (probably) the largest amount out of the drainage area, main channel length, basin relative height, the average main channel slope, watershed cut density, the main Groove bending coefficient, loose solid material storage, sediment supply length ratio, the maximum 24-hour rainfall; calculate index weights for each level, the integrated impact of debris flow hazard by the total weight of the indicators. Along the 147 final calculation of the risk of storm debris flow. The use of ArcGIS software, the intuitive risk situation is reflected in the DEM map. It is found that, Mainling County high risk of development of more landslides, and is consistent with the field investigation. In order to verify the accuracy of the method, from 147 randomly selected debris flow channel 12, the use of Liu Xilin, TANG Chuan and other debris proposed a simplified method of risk assessment methods, this method results and the results of this modeling approach proposed agreement Rate good, is feasible.