Analysis Of Water Supply Satisfaction Degree And Pipeline Importance Of Water Distribution System

Water distribution system(WDS)is one of the necessary systems to ensure the normal operation of the city.In recent years,remarkable achievements have been made in the construction and renovation of water supply networks in China.However,problems such as water leakage,pipe bursts,insufficient water supply pressure,unqualified water quality and secondary pollution still exist,which have a negative impact on people's daily life and production.How to reduce the accidents,limit water resource losses and meet the requirements of safety,durability and reliability have become a hot issue in the long-term operation of WDS.In this paper,we propose the indexes of node water supply satisfaction degree and pipeline importance to evaluate the service ability of water supply network and the impact of pipeline failure on users' demands,based on the current WDS reliability studies.The aim is to provide some theoretical help for project managers to find the water-deficient areas in the pipeline network and to optimize the pipeline renewal and maintenance schemes.Firstly,in order to simulate the hydraulic performance of water supply network under insufficient pressure after an accident,the pressure-driven method is used to solve the network model based on the current researches of the relationship between node flow and pressure.The application of pressure-driven method and traditional demand-driven method under pipeline failure or water source failure are compared in two cases.The results show that there is a big deviation between the calculation value and the real value of nodal pressure by demand-driven method under accident conditions.With the increase of accident severity and the aggravation of water shortage,the deviation will be greater.By contrast,the pressure-driven method takes into account the decrease of node water demand under insufficient pressure,and the calculation results are more reasonable.Secondly,water supply satisfaction degree index is defined,from the perspective of user's satisfaction degree of water demand,to evaluate the performance of water supply service in accident.Then the influence of pipeline failure on node demand is analysed,and pipeline importance index is defined.Using the WDS hydraulic model,the proposed method is finally validated in real casesThe results shows that the analysis of node water supply satisfaction degree can accurately identify the weak areas(water-deficient areas)in WDS,and the calculation results are presented in a visual way,which is convenient for managers to evaluate the operation state of nodes.The pipelines in the low satisfaction degree area are then evaluated.The proposed pipeline importance index can effectively identify and mark the high influence degree pipe,especially in some areas with complex networks.Instead of only relying on engineering experience,the analysis results are more reliable.It can be used to formulate future pipeline maintenance strategy and find potential water supply dangers in the pipeline networks.