Lifecycle operational resilience assessment of urban water distribution networks

This paper proposes a lifecycle operational resilience assessment framework of urban water distribution networks (WDNs), taking accidents, pipe deterioration, and restoration into account. First, the accident occurrence rates for three common types of pipes, namely, cast iron pipes (CIPs), ductile iron pipes (DIPs), and steel pipes (SPs), are fitted using the maintenance data provided by a water administrative sector. Second, for the two most common accidents, i.e., leakages and bursts, the accident pipes in the former case are simulated by reduced flow, while the accident pipes as well as the influenced ones in the latter case are isolated completely by closing valves, which are determined by a depth-first search method. Third, two restoration strategies are considered, including plugging and replacement, and the corresponding recovery time by days are given based on the maintenance data. Meanwhile, the aging induced pipe deterioration is modeled in the operation process. Finally, the operational resilience of the WDN in Mianzhu city is evaluated by above framework and six resilience strategies are investigated and compared. Results show that replacing accident pipes with new DIPs once burst occurs improve the operational resilience of WDNs most obviously. In addition, replacing CIPs with DIPs ahead of the design working life or adding valves also help to improve the resilience level. Based on the findings, some feasible and practicable resilience enhancement suggestions are concluded to provide guidance for local decision makers.