Optimal Location Of Water Quality Monitoring Stations For Sudden External Pollution Of Water Supply Network In Mountain City

Water supply network is a kind of important urban infrastructures,involving the national economy and people’s livelihood,and closely related to the health of residents.Due to the complex topological structure and wide distribution of the water supply network,the urban water supply network is unable to achieve all-weather regional monitoring,which provides an opportunity for sudden external pollution(intentional poisoning,etc.).When the water supply network burst of external pollution,it will bring adverse effects on the life of residents.How to establish an effective rapid response mechanism to deal with sudden external pollution and reduce the harm brought by sudden pollution is worthy of study.Firstly,it is necessary to quickly monitor the sudden pollution events and gain favorable time for the decision-makers in the water supply industry.This study is funded by "National key research and development program(2017YFC0404706)",based on the characteristics of mountain city water supply network,using the quasi dynamic hydraulic model.The goal of optimized location model is to minimize the variance between average shortest monitoring,minimize the monitoring time and maximize monitoring coverage,besides,we use the NSGA-Ⅱ algorithm to solve it.All we do is for mountain city water supply network to cope with sudden exogenous pollution provide optimization arrangement of water quality monitoring technology.(1)First of all,set up dynamically hydraulic pipe network model by using EPANET 2.0 software,it can simulate the real operating mode of water supply network.Besides,we can also get the different time network transmission time matrix adjacency node which on behalf of corresponding hydraulic conditions.Then we use the Dijkstra algorithm to get the shortest transfer time matrix between any node,arbitrary nodes shortest transmission time matrix is stored as the basic database,provides the basis data for solving the mathematical model.(2)Secondly,a three-objective optimization model aiming at "the shortest average monitoring time,the largest monitoring coverage and the smallest variance between monitoring times " is constructed.Combined with the characteristics of quasi-dynamic hydraulic model and sudden external source pollution,the traditional mathematical model of "the shortest average monitoring time and the largest monitoring coverage" was improved,and the third goal of "the smallest variance between monitoring time" was innovatively introduced.In addition,according to the importance of users and water consumption of pipe network nodes,the probability of sudden pollution occurring at pipe network nodes is differentiated and reflected in the mathematical model,which effectively improves the reliability of water quality monitoring system in response to sudden external pollution.(3)Thirdly,the solution mode of multi-objective site selection model based on NSGA-Ⅱ algorithm is proposed.Three-target optimization model,aimed at improving the NSGA-Ⅱ source code on the MATLAB platform,by calling the basic database(the shortest transmission time matrix)to optimize the location model.And through the network example verification,the results show that the “variance between monitoring time” can provide the decision basis of the third dimension for water managers,which can effectively improve the reliability of water quality monitoring system.(4)Finally,this paper puts forward a plan of the water quality monitoring stations optimization layout for mountain city in water supply network to deal with sudden pollution.Combined with the typical characteristics of "multi-source + mixed partition" of mountain city water supply network,the pipe network partition was effectively divided,and the improved three-objective optimization mathematical model was used to solve the mathematical model based on MATLAB platform and NSGA-Ⅱ algorithm,so as to determine the final water quality monitoring stations layout plan.