Evaluation of Urban Water Distribution Network Under the Combined Hydraulic and Mechanical Reliabilities

Network reliability is one of the most important parameter when evaluating the efficiency of water distribution networks (WDNs). WDN reliability is calculated based on the mechanical, hydraulic and water quality aspects under normal and also abnormal conditions such as system failures. In this paper, hydraulic reliability was calculated through the ratio of satisfied nodal demands. In this regard, hydraulic simulation is performed based on the proposed EPANET-IMNO algorithm based on a Pressure-Driven Simulation model. This algorithm is written in Visual Studio through C⁺⁺ code. The mechanical reliability of the network was evaluated by means of BDD algorithm based on  probability of having a connection between the source nodes and consumption nodes. DNA and RNA tools are used to evaluate the mechanical reliability based on BDD method. Finally, an integrated reliability is proposed for optimum design and operation of WDNs. A looped WDN with nine nodes and a branched WDN were considered in this paper. The results showed that besides the hydraulic reliability the evaluation of mechanical reliability index is very important in the design of WDN to improve the operation of WDNs. Adding 4 loops to the branched WDN increased its reliability by 18.3%. Also, it was determined that under a looped WDN eliminating one pipe in the worst case may reduce the network reliability by28%.