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Resilience: a citywide analysis of flood and CSO mitigation in NYC




Furth, D. Canon, author
Arabi, Mazdak, advisor
Sharvelle, Sybil, committee member
Bradley, Thomas, committee member

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The implementation of green infrastructure (GI) for flood and combined sewer overflow (CSO) mitigation has been increasing in popularity in highly urbanized settings due to overloading of the centralized systems. The utilization of decentralized systems permits dispersed adoption, supplementing the installed grey infrastructure. Large cities, in part due to density and their impervious nature, tend to fall victim to these negative responses. A resiliency study was performed on New York City, which entailed detailed modeling of five different storm scenarios and four unique intervention scenarios using InfoWorks ICM. Storm Scenario 1 (SC1) is the 1 inch, 1-hour storm, SC5 is the 1.8 inch 1–hour, 5-year storm, SC6 is SC5 with 1.3 ft of surge, SC9 is the 2.6 inch, 3-hour, 5-year storm and SC18 is the 9.1 inch, 24-hour, future 50-year storm with 3.1 ft of sea level rise. Scenario I1 represents constructed and imminent green infrastructure planned for implementation through 2035, I2 evaluates how Long-Term Control Plan (LTCP) grey infrastructure effects flooding in NYC, I3 represents the additional distributed infrastructure throughout the City that would be required by the onsite water management rules for both combined and separate sewers, and I4 evaluates how additional grey infrastructure impacts flooding. A few key findings include the reduction of CSO volumes at NYC outfalls ranging between 2 to 90 percent, and that green infrastructure systems were most effective in controlling smaller storm scenarios. This study further hones in and examines how the implementation of GI will impact flooding in the City as a whole and per sewershed by exploring the variability in responses and effects under varying precipitation regimes and projected sea level conditions. This study also explores the complementary and substitutive effects of green and grey infrastructure systems by examining sewershed conditions, precipitation regimes, and management goals.


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green infrastructure


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