基于二项分布的单沟泥石流危险性定量分析方法

This applied project aims at proposing quantitative analysis methods of individual debris flow hazard based on probability analysis. Debris flow hazard will be expressed by the term of expected magnitude, and multiple research techniques will be adopted, including data collecting, gully investigating, mathematical modeling, and GIS based analyzing,to discuss the calculating and analysis approaches of exppected magnitude of individual debris flow. A calculating procedure of occurrence probability of debris flow based on binomial distribution will be rectified into another procedure which can calculate occurrence probabilities of debris flows with different return periods. The rectified procedure, integrating with a calculating procedure of magnitudes in different return periods, which is mainly based on experiential models, will be used to form a curve fitting procedure of magnitude-probability expression and a calculating procedure of expected magnitude of individual debris flow. The procedures will be optimized through a comparative analysis with real evidences in Jiangjia gully in Xiaojiang river basin, Yunnan province. Furtherly, using conditions of the procedures will be defined by summing up the results of case studied in Xiaojiang river basin. Besides, the case studied results will be used to investigate a quantitative hazard grading method of individual debris flow..This project will propose a quantitative ananlysis method in individual debris flow hazard, which falls in between the index analysis method and mechanism analysis method. This method can provide the results of expected magnitude of debris flow in a certain years and will be characterized with easily available input data and low demand techniques. It is believed that the proposed method can be applied in the quantitative analyses of debris flow risk and the actuarial studies of debris flow disaster insurance.

本申请项目拟探讨基于概率分析的单沟泥石流危险性定量分析方法。项目选用期望规模表征泥石流危险性，综合运用资料收集、沟道调查、数学建模、GIS分析等技术手段研究单沟泥石流期望规模的计算和分析方法。首先，通过修正基于二项分布的泥石流发生概率计算方法，提出一定时期内不同重现周期泥石流发生概率计算方法，结合以经验性模型为主的不同重现周期泥石流规模计算方法，提出规模-概率关系式拟合方法和单沟泥石流期望规模计算方法。然后，通过与云南小江流域蒋家沟泥石流实测资料的对比分析优化计算方法，通过小江沿岸泥石流沟的实例分析，界定计算方法的适用条件，探讨定量的单沟泥石流危险性分级方法。.本申请项目将提供一种基于指标分析法和机理分析法的单沟泥石流危险性定量分析方法，能够得到一定时期内泥石流期望规模值，而且基础数据易得、技术要求低，在泥石流灾害风险定量分析、保险精算等领域均有应用前景。

本项目致力于建立基于概率分析的单沟泥石流危险性分析方法。项目围绕指标的选取、模型的建立、数据的获取等关键问题，选取了期望规模作为泥石流危险性的代表性指标，引进并论证了二项分布概率模型，推导了具有物理意义的期望规模计算模型，提出了期望规模的实用计算方法。在此基础上，定义了基于期望规模的单沟泥石流危险量概念，建立了危险量与危险性等级的数量关系，初步实现了单沟泥石流危险性的概率分析。为了能够区分不同区域的泥石流活动特征，项目还补充开展了区域泥石流活动性调查研究，为今后开展更为精细的泥石流危险性概率分析奠定基础。由于计算模型的推导较为困难、耗时较长，支撑数据也较为缺乏，因此实例分析工作相对滞后，计算模型有待进一步验证和完善。.项目的研究结果表明，期望规模兼具严重性和可能性，是比较理想的泥石流危险性指标；采用二项分布作为泥石流发生概率模型，相比泊松分布更符合泥石流的活动特征，更适于期望规模的计算；推导的计算模型将期望规模的时间期限从1年拓展到n年，定量描述了泥石流危险量的时间性，丰富了泥石流危险性的内涵；危险量与危险性等级的数量关系能够更形象地描述危险性等级的含义。.项目研究成果有助于开展定量化程度更高的泥石流危险性分析，在泥石流防治工程设计、泥石流风险性的定量分析、泥石流灾害保险精算等领域具有广阔的应用前景。