Study On Risk Analysis And Disaster Loss Assessment Of Dam Break Based On Cloud Model And GIS/RS

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.