Risk And Consequence Assessment Of Water Supply Network Based On Logistic Regression And Analytic Hierarchy Process

In urban water supply network systems,the pipelines are a very important component.Especially leaks and bursts are very useful indicating parameters to show the condition of the network.Pipe bursts and leaks may result in reduction in the supplying capacity of the pipes and also increases the chance of contamination in the supply network systems.Water supply utilities consumes large amount of budget in the maintenance.Therefore,it is very important to evaluate the bursts of these pipes.For keeping and improving the performance of the supply s ystem,it is very much essential to evaluate the current and future condition of the system for replacement,rehabilitation and maintenance decision making.Evaluating the burst condition of water pipes is a complex work,partly due to the lack of complete maintenance records and field determining pipe bursts and their probabilistic relationship with the deterioration process.In this thesis,two factors are considered for the evaluation purpose and they are consequence of failure probability(likelihood of burst)and consequence of failure.Consequence of failure probability model for pipe burst risk was developed with various pipe burst-repairing data recorded and the local characteristic circumstances.The method used was logistic regression analysis,the goal of this model is to find the likelihood of pipe bursts in the future and determine the parameters that most affect the likelihood of pipe bursts.Data included the pipe diameter,pipe material,depth of laying,road width and pipe age.The data set used for analysis comes from a major XY city of China,and these data includes approximately 148,676 pipe segments data included with nearly 127,764 bursts were detected from past 40 years.The consequences of failure(COF)model that uses a weighted sum multicriteria decision making method based on expert opinion to assess the economic,social,and environmental consequences of water bursts pipe failure.The model includes many factors consisting of economic impact,social impact and environmental impact arranged into a hierarchical model to determine one final consequence-of-failure score.The analytic hierarchy process(AHP)was used to determine the relative importance weights of all factors and criteria.The results show that economic cost factors are the most important to evaluate when determining an asset's consequence of failure.The overall bursts rate condition of the city was found to be in moderate consequence of failure.