Study On Systematic Methods Of Vulnerability Analysis And Risk Assessment For Municipal Water Supply Systems

Municipal water supply systems as one of lifelines of a city, it plays an important role to guarantee the city operation normally. However, the municipal water supply security is threatened by the aging pipe network, natural disasters, terrorist attacks or other emergencies seriously, and it has become an important component of the city safety and disaster prevention systems. Therefore, it needs to establish a set of risk assessment technology approach to ensure the safety of water supply. The studies before mainly concerned the specific water supply subsystems or threat, and lacks of systematic. Against these problems above, the systems science theory and computer technology were used comprehensively in this paper, and a set of risk assessment systematic approach for water supply systems was proposed, which could provide technical means for the security design of water supply systems.Firstly, against the function catastrophe characteristic when the water supply subsystems suffered by the emergency, the catastrophe theory was used to analyze the catastrophe mechanism, and a function catastrophe simulation model for water supply subsystems was established accordingly. On this basis, the vulnerability index systems of water supply subsystems was founded, and a vulnerability assessment model of water supply subsystems which based on catastrophe series was proposed. Then, a water distribution subsystems was taken as an example to verify the feasibility of the method. It can be found from aplication that the method proposed above has overcomed the subjectivity dificiencies of the previous vulnerability assessment methods.Secondly, against the uncertainty of emergency which the water supply subsystems will be suffered, the entropy function which was the indicators of disorder and uncertainty in physics was used to analyze and assessment the risk of water supply subsystems. And the concept and computer formula of risk entropy for water supply subsystems were proposed. Then, a water distribution subsystems was taken as an example to verify the accuracy of the method above. It can be found from aplication that the method proposed above could used to solve the uncertainty when to assessment the risk of water supply systems.Thirdly, against the systematic problems of risk assessment of water supply systems, the collaborative connection and effect mechanism between the different water supply subsystems were analyzed, and the logical stucture mathematical model of water supply systems was established based on the series, parallel systems theory. Then, the risk transmission theory was applicated to explore the risk transmission mechanism, and the risk transmission mathematical model of water supply systems was founded. Through this study, the results could be used to solve the systematic problems in the risk assessment process of municipal water supply systems.At last, the Tanggu District's water supply systems of Tianjin was taken as an example, and the catastrophe series method and risk entropy model were used to compute the vulnerability and risk of Tanggu District's water supply systems. Then, the risk transmission mechanism when the water supply systems suffered by the earthquake was analyzed, and the total risk was certained based on the risks of the water supply subsystems. Through the case studies, it validated the accuracy of the method and model which proposed in this paper.