Water Infrastructure Resilience Index

摘要

Risks associated to water infrastructure failure are increasing. Since risk is usually measured as a function of probability of failure and consequence of failure, risk changes accordingly to change on its two factors. Probability of failure is increasing due to more frequent extreme climatic events, manmade disasters, and growing vulnerabilities from ageing processes.Consequence of failure is also increasing since population is growing and concentrating in urban areas. Urban populations are dependent on infrastructure services. For civil infrastructure systems, an only protection-based risk management approach will not work because some disruptive events such as climatic extremes cannot be avoided. A Complete approach must integrate protection and resilience, as recognized on the 2009 update of the National Infrastructure Protection Plan. This paper presents advances on a simulation model for assessing the resilience of any water infrastructure system. The system resilience is expressed as a Resilience Index. Resilience is estimated using performance metrics for water quantity and quality, and is based on two frameworks, namely the Multidisciplinary Center for Earthquake Engineering Research’s (MCEER’s) four R’s: Robustness, Redundancy, Resources, and Rapidity; and a recovery time and cost framework. A set of standardized hazards from different possible disasters is applied to a network model of the water system. Likely damage is recorded and the recovery time and costs are estimated. As a result of this process, it is possible to estimate a resilience index for the specific system, given available recovery resources. The resilience index is related to the likelihood of a resilient response from the system in case of disruption. It is expected that any water infrastructure system will have different resilience indices for different types of disruptive events. A novel feature of the Resilience Index is that considers condition of the system as an input. The inclusion of system condition is useful to estimate the impacts of ageing processes, maintenance backlogs, or even planned improvements over the system’s resilience capacity. Research on this Resilience Index is an ongoing effort, andrnsome preliminary results may be presented, although this is not a finished research yet.