Resilience of Water Distribution Networks

Resilience is widely interpreted as the capacity of a system to resist (preparation phase), absorb and withstand (responding phase), and rapidly recover from (restoration phase) exceptional conditions. During this study, a mixed variety of calculations were assessed in order to find the best solution for determination of resilience and reliability of a simple network. Then, Todini’s formula and failure index was applied to estimate reliability of system in different scenarios as constant demands in period of 24 hours, constant demands in period of 72 hours when tank will be empty (failure of tank), variable demands in period of 24 hours. At first hydraulic simulation of those scenarios was done by EPANET and validated by MATLAB-TOOLKIT. Then, Resilience index (RI), Failure Index (FI) and reliability (R) of system were measured. Finally, an optimization procedure was done to make a water distribution network with highest resilience and lowest failure probability. All these procedures have been applied on a real network as WDS of Modena. It concluded that this method can be used for every water system without considering the type of failure. As a result, first scenario has a constant decreased and increased trend of RI and FI respectively because of diminishing of water level in tank. During second scenario, there is significant change after the tank will be empty (or it is broke). Third scenario is more like a real network with variable demand during a day. It was concluded that there is a minimum resilience parameter during day when a peak time of water demand expected. It can be justified that the reservoir and pump system had to sustain more pressure to satisfy the demands of junctions. Maximum resilience is related to night during a day with less demands and providing water by tank to other junctions. This modelling could be useful to optimize the dimensions and features of instruments to increase availability and reliability of system.