A Hazard-Vulnerability-Risk Approach to Estimate Losses Produced by Water Distribution Pipe Breaks

Pipe bursts in water distribution systems are infrequent but unpredictable events that can lead to significant economic and social consequences, especially when they result in overland flooding affecting streets, buildings, and other infrastructure. In regions of the U.S. and Canada, where aging water systems are prevalent, the likelihood of pipe bursts is increasing, further exacerbated by seasonal temperature fluctuations.

A hazard-vulnerability-risk approach is implemented in a tool in PCSWMM to estimate these consequences. The hazard component is assessed by calculating the likelihood of bursts for each pipe and generating a 2D flooding model for the city's surface area. Vulnerability is evaluated using damage curves for overland flooding found in the literature, and risk is quantified as expected annual losses.

A case study is conducted at an undisclosed location to demonstrate the approach. Key findings include: 1) Losses from pipe bursts are influenced by factors such as pipe size, local topography, proximity to exposed assets, and the presence of highly vulnerable assets; 2) Accurate estimation of pipe burst probabilities is critical for the validity of the simulation results; and 3) Graphical representation of simulated flooding extents is essential for understanding the broader impacts of a pipe burst beyond the direct damage to infrastructure.

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