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基于云模型和GIS/RS的坝堤溃决风险分析及灾害损失评估研究

Study on Risk Analysis and Disaster Loss Assessment of Dam Break Based on Cloud Model and GIS/RS

【作者】 江迎

【导师】 张秋文;

【作者基本信息】 华中科技大学 , 空间信息科学与技术, 2012, 博士

【摘要】 水是生命之源,人类社会的生存和发展离不开水。早在公元前三千年,世界上就开始了坝堤工程的修建,坝堤起到了储备水源、蓄水发电还有防止洪涝等功用。但是坝堤溃决灾害造成的危害也是非常巨大的,因此坝堤工程的安全是关系到生命、社会以及环境的重要问题。坝堤溃决风险评价方法可以帮助评价坝堤的安全状态、找到坝堤的风险源,直接指导坝堤的安全管理工作,从而保证坝堤工程的安全。本文对国内外坝堤溃决典型案例进行详细剖析,在总结了溃坝事故特点的基础上,系统的研究了坝堤溃决的模式,并进行了坝堤风险的机理分析,从而辨识出导致溃坝的主要风险因子,并根据各个风险因子之间的层次关系,构建出坝堤溃决风险指标体系,为建立坝堤溃决风险评价模型和实施风险评估提供前提条件。在坝堤溃决的研究中,要从有限的充满模糊性和随机性的数据中对其风险进行量化是非常困难的。现在已有很多理论方法被应用到坝堤溃决风险评价中,但是这些方法往往忽略了评价过程中的不确定性,同时也缺少有效简单的定性定量的转化模型。在风险指标体系中的各个风险因子有着各自不同的状态和重要性,它们对于最终评价结果的贡献各不相同,所以每一个因子都有自己的权重和风险度。传统计算风险因子关联权重的方法是层次分析法,一般利用整数及其倒数来表征两两因子的关联重要性并构建判断矩阵,但是这样不能正确的表现出判断的模糊性和随机性。而作为传统的处理模糊问题的方法——模糊数学,需要利用隶属度来转化不确定性。但是当利用确定的隶属函数表征模糊性时,模糊问题将不再模糊。结合了模糊性和随机性的云模型可以实现定性到定量的转化。针对传统的层次分析法和模糊评估方法的不足,将云模型应用到评价方法中来,与层次分析法和模糊数学方法相结合,建立基于云模型的综合评价模型。本文提出了一种基于重要性标度云模型的判断矩阵改进层次分析法,并且利用云模型来确定模糊方法中的隶属函数,接着利用集结云模型来进行群体决策,最后通过实例以证明方法的可行性和有效性。由于坝堤溃决造成的洪水破坏力非常巨大,特别是会造成大量的经济损失以及人员伤亡,对洪水灾害造成的损失进行评估,可以为抗洪救灾以及坝堤的加固除险提供决策依据。本文通过分析洪水淹没灾害的属性特征,阐述了利用GIS和RS进行洪水淹没损失评估的基本原理。在考虑到连通性的情况下,利用DEM数据和ARCGIS软件来计算上游的洪水总量以及下游的淹没范围和水深。接着利用遥感软件处理遥感数据获取淹没区域土地利用类型,通过空间分布方法来得到社会经济财产的分布,将财产分布与洪水淹没区域进行叠加分析,根据不同水深下社会经济财产的损失率来获取最终的总体灾害损失。最后,综合考虑坝堤溃决风险度以及洪水淹没损失的评估结果,来对坝堤的整体安全度作出最后评价,针对不同坝堤工程,分别从这两个角度来进行比较,为坝堤工程的除险加固决策提供可靠的依据。

【Abstract】 Water is the fundament natural resource and strategic economic resource. It is impossible the basal existence of people and the sustainable development of the social economy without water. Dams have been built to make full use of water resources in many countries. The risks caused by breakage of the dams could be very serious, which have been constructed for a number of purposes such as provision of drinking and irrigation water as well as generation of electric power. Therefore the security of the dam is a vital problem in life, society and environment. It is of necessity to build the system to analyze and evaluate the security risk and safe state of dam. Dam failure risk assessment system can help evaluate the dam safety condition, locate the weak link of the dam, find the key factors affecting the dam safety, direct the management of dam security and guarantee the dam safety.Anatomizing the typical cases of the dam break both home and abroad, and summarizing the characteristics accidents, based on which a system atic research is conduceed on the dam break pattern. The primary risk factors of dam break can be distinguished based on correlation analysis. And the dam break risk index system can be set up following the relation and arrangement of the risk genes, which provides a precondition for the research of dam failure risk evaluation model and assessment method.The traditional methods to determine the relative weight of each factor in the index system is Analytic Hierarchy Process(AHP), which uses paired comparisons to derive a scale of relative importance for alternatives and then construct a pair-wise comparison matrix using a scale of relative importance. In the judgment matrix, the integer and reciprocal are usually used to express the different importance between two factors, however it can not describe the fuzziness and randomness of the judgment accurately. As a main tool to deal with the fuzzy problem, the fuzzy sets theory curves the fuzzy things’ uncertainty by the degree of membership. However, once the fuzzy sets are described by a membership function, the concept of fuzziness will be no longer fuzzy.The cloud model can realizes the transition between precise value and quality value by combining the fuzziness and randomness. And the cloud model is introduced into the assessment of dam break risk, which is combined with AHP and fuzzy method, and then the comprehensive assessment of dam failure risk can be realized. The improved AIIP based on judgment scaled with cloud model is proposed, and the cloud model is used for determining the membership function in fuzzy method, finally the group decision can be gained with the synthetical aggregated cloud model. The method’s feasibility and effectiveness are shown in the practical examples.The brisanc of flood is very tremendous following the dam break, in a large extent because of floods-caused economic losses and casualties, so the loss assessment of flood disaster may be used to provide the decision-making basis for flood relief and dam’s reinforcement. The attributes and features of the flood submerging disaster have been analysed in this paper, and the postulate of flood submerging disaster loss assessment is expressed with the GIS and RS technics. In view of the connectivity of flood, the upstream flood volume as well as the submerging scope and depth have been calculated with the Dem data and Arcgis technique. Then, the RS data shloud be disposed to extracte the land-use type of the submerging area, and the distribution of socio-economic properties can be gained with the space distribution methods. The distribution of properties and the flood submerging area were overlay analysized to obtain the the distribution of socio-economic properties under different submerging depth, the final total loss cloud be gained based on the loss ratio under different depth.Finally, the risk degree of dam break and the eveluation of flood submerging loss cloud be compositely considered, which can give a hand to making the final assessment of the integral degree of safety of dam. The degree of safty of different dams can be compared follow the two perspectives and the result is the reliable evidence of the decision-making of the dam reinforcing selection.

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