Citywide Stormwater Resiliency

Boomi led the hydraulic modeling, and flood risk mapping efforts to support this citywide stormwater resiliency project geared towards identifying at-risk areas.

Project Owner

New York City Department of Environmental Protection (NYC DEP) - Bureau of Environmental Policy and Analysis (BEPA)

Project Location

New York City

Project Context

New York City has experienced severe and frequent flooding during storms, hurricanes, and tidal surges that repeatedly occurred in the recent past. DEP along with the Mayor’s Office initiated a comprehensive study to identify at-risk areas for different storm/tidal surge conditions.

Project Challenge

The scale of the existing hydraulic model was not sufficient enough to accurately characterize the surface routing and flooding which was needed to identify at-risk areas at a local-scale. In addition, for this citywide effort, different modeling approaches and SOPs were to be followed for the different sewersheds across the City.

Our Solution

First the existing H&H model was enhanced with high-resolution sewer network and two-dimensional (2-D) grid to accurately characterize the surface routing and flooding. The model expansion was tailored to each wastewater resource recovery facility (WRRF) service area based on anecdotal flooding data. Available flow metering data in the service areas to various WRRFs, along with available anecdotal flooding data were then used to validate the models. Subsequently, these models were used with the 100-year and 10-year short duration storms to characterize the system vulnerability. The effect of sea level rise was also modeled for select rain events. The modeling approach was refined for separately sewered areas and unsewered areas of the city. Flood risk maps were then prepared to disseminate the findings of this study and inform the government and elected officials of the vulnerability in various neighborhoods. To mitigate the flooding risks identified, Green and Grey interventions were also conceptualized.