Modeling post-earthquake water recovery periods and application to central Tokyo

Tokyo Metropolitan Area. This study aims to establish a method to model the recovery of the water supply system in cities after a disastrous earthquake. Based on observed post-earthquake recovery of the water supply system in Japan, this study proposes a method to estimate the geographic distribution of water supply restoration period (days) and applies it to the densely populated region to demonstrate the existence of locations as significant water outages. By analyzing past cases, the period until the local water supply is fully restored is estimated for each of the areas at risk of liquefaction and those not. Subsequently, a method to generate geospatial information on the days until the water supply is restored within the target area is proposed using geographical dataset. The percentage of water supply restoration over time is consistent with that observed during a recent earthquake. The amount of water shortage calculated using Tokyo as an assumed scenario, which reflects the spatial-distribution of water outage population and durations, is higher than the estimates obtained from government-based damage simulations. This study demonstrates the vulnerability of the Tokyo Metropolitan Area to water shortages during shutoff periods owing to earthquakes. The differences in risk in liquefaction-prone areas emphasize the importance of considering detailed regional information when addressing temporary water shortages associated with earthquakes. • Modeling method for restoration period of the water supply system after earthquakes. • Recovery time based on past earthquakes mapped to high resolution grid. • Visualize spatio-temporal changes in water risk as quantities for disaster preparedness.