Hindcasting the Functional Loss and Restoration of the Napa Water System Following the 2014 Earthquake Using Discrete-Event Simulation

Abstract

Models that simulate postearthquake functional loss and restoration of water distribution systems support the development and implementation of more informed resilience-enhancing strategies. This study uses pipe damage, repair data, and a discrete-event simulation (DES) model to hindcast the water system damage and functional loss and restoration, following the 2014 South Napa earthquake. The DES model represents the water system as a set of entities (e.g., pipes, tanks, pumps) that interact through a sequence of events (e.g., earthquake damage, inspection) of variable duration that may be triggered at different points in time depending on the entity attributes (e.g., pipe vulnerability), access to resources (e.g., inspection crews), and the completion of other events. In addition to pipe damage and time-dependent inspection and repair processes, the DES model incorporates a pressure-driven analysis (PDA) that captures the restoration of water availability following the event. The tuned DES model is then used to simulate the postearthquake disruption and restoration of the City of Napa’s water supply for a Mw 6.7 event on the West Napa fault. By propagating the uncertainties in the damage to the network components (e.g., pipe) conditioned on the shaking intensity and the temporal (e.g., repair time) and resource-related (e.g., the number of inspection crews) variables, probabilistic descriptions of network component repair and water service restoration are generated.