| Located in the edge of mountain glaciers and snow cover, solid substances are mainly old and new ice from the debris of the supply of carbon and avalanches, water dependent on snow melt water and glacial lake outburst known as glacial debris debris flow of water. Based on previous research and analysis of information collected and a detailed field survey their own work, based on existing research results from home and abroad, research methods, to identify the Brahmaputra plus check-Nyingchi segment formation of glacial debris flow conditions, development features, Distribution factor to affect the sensitivity of glacial debris flow factors, and established for the study area, glacial debris flow hazard assessment indicator system and grading standards, based on the use of "fuzzy comprehensive evaluation" system for quantitative evaluation, to achieve the following main results:(1) considering the results of previous studies of glaciers in the study area and the actual situation of this debris Select Optional:drainage area, channel bed longitudinal slope, lithology coefficient, the mean temperature, glacier slope, watershed relative height, solid material reserves, Glacier area and the ratio of watershed area as the study area eight factors important factors of debris flow factor, and use the "gray relational grade" analysis to determine the glacial debris flow sensitivity analysis of selected factors.(2) For the calculation of the weight, the use of the "Analysis of Effect Measure" and "Grey relational grade," the combination of comparative method, to avoid subjective judgments are caused by human error, greatly to keep the original field data.(3) The calculation of fuzzy comprehensive evaluation process, the fuzzy comprehensive evaluation of many algorithms, in order to avoid a single algorithm to bring the error is too large, this single factor taken into account the weight and overall evaluation of all factors of the two methods and Weighted average of the results of two methods, namely, the fuzzy comprehensive evaluation method used in the "∨,·" operator,"+,·" operator," "∨,·" and "+,·" weighted average " operator.(4) In determining the evaluation set V of the upper and lower value limits, this paper is:in the objective field survey data, the various factors factor of real numbers R as the domain of the case, the definition of each factor factor of real number as a valid value, statistics in the study area Glacial debris flow minimum value of each factor x1, average x2, x 2 and to average risk in the moderate middle, on this basis, the separation between x1 and x 2 2.5 interval, and then define the various risk Grade threshold value. This method reflects the objectivity of evaluation sets, maximizing the use of the original data, thus avoiding the risk of subjective definition of class boundaries so that part of the original data loss situation.(5) get fuzzy comprehensive evaluation of 53 debris flow deposit, in general, there are two risk, mild risk are 19, there are 17 moderate risk, high risk, there are 15. At the same time risk assessment model in this paper is typical of the two glacial debris flow (G3, G30) calculated and compared fuzzy comprehensive evaluation method, evaluation results, indicating that the fuzzy comprehensive evaluation methods to evaluate the glacial debris flow is feasible.(6) the use of fuzzy comprehensive evaluation of the results of the study area of the glacier debris flow hazard maps to make risk assessment. |
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