Dynamic modeling of sea-level rise impact on coastal flood hazard and vulnerability in New York City's built environment

There is a consensus that future sea-level rise (SLR) will increase the exposure of population and assets to coastal flooding. However, the extent to which SLR affects flood hazards and human vulnerability to flooding in the built environment is not well understood. This study investigates the effects of future SLR on coastal flood hazards and human vulnerability to flooding in New York City's built environment. With a focus on a hurricane-induced flood event, we utilize a building-scale hydrodynamic model to simulate flood hazards under different 21st-century SLR scenarios. We further implement a human vulnerability model to reveal how the physical vulnerability of individuals to flooding would respond to the effects of SLR on flood hazards. We find that SLR would result in a substantial increase in not only the floodwater depth but also the floodwater velocity in the study area. For example, under a 1.04 m SLR scenario, the increase in the max floodwater speed exceeds 2.7 m/s (1271%) in 5% of the area that was flooded under the no-SLR scenario (control run). Model results show that, due to nonlinear interactions, the floodwater depth simulated by the hydrodynamic model for a SLR scenario could substantially differ from the depth estimated based on a linear addition of the SLR to the control-run floodwater depth. We find that the effects of SLR on flood hazards would, in turn, substantially affect the extent, intensity, and duration of human physical vulnerability to flooding, which could potentially increase the number of injuries and mortalities.