Impact of Water Network Uncertainties on Seismic Rehabilitation Decision-Making for Water Pipelines

Past earthquakes have revealed the vulnerability of water infrastructure to earthquakes as water networks are susceptible to pipe damage (breaks and leaks). These damages can disrupt in the supply of water distribution. Seismic vulnerability assessment is essential for seismic rehabilitation decision-making. Although water pipe network uncertainties play a critical role in seismic vulnerability assessment methods, the impacts of these uncertainties have not been explored in optimal proactive seismic rehabilitation decision-making. Extant pertinent literature ignores the uncertainty related to water network properties. This research aims to explore the impacts of water network uncertainties on determining the most critical pipes vulnerable to seismic events within a limited budget constraint. Pipe roughness coefficient, demand, and reservoir head were selected as uncertain network parameters for this study. Sensitivity analysis was performed to quantify selected network uncertainties. A stochastic combinatorial optimization problem was formulated considering network uncertainties and seismic ground motion intensities to identify the most critical pipes of a network for limited rehabilitation budget. A simulated-annealing algorithm was used to solve the stochastic combinatorial optimization problem. Modena network was used to demonstrate the method. The optimization results showed that the selected network uncertainties significantly affect the identified critical pipes of the water pipelines. Also, the maximum achievable serviceability index for selected rehabilitation budget reduces significantly if network uncertainties are considered. This index has been reduced by 3%−4% due to the consideration of all three network uncertainties. It can be concluded that network uncertainties must be included with the current methodology of proactive rehabilitation decision-making due to seismic events.