Characterizing the mechanisms of urban flooding during cloudburst rainfall events

Katelyn M. Singh

doi:10.17918/00011078

Changes in precipitation patterns driven by climate change pose a growing threat for urban areas, where conventional drainage systems are often undersized to manage runoff from intense rainfall. Cities around the world have begun to implement stormwater management strategies to prepare for cloudbursts--short-duration, high-intensity storms. While citywide cloudburst planning and green infrastructure have received growing attention, there remains a critical gap in understanding the localized mechanisms of flooding during extreme events. This study uses an all-pipes hydrologic and hydraulic model to characterize specific drivers of urban flooding in Kissena Park, Queens, New York City during the remnants of Hurricane Ida in 2021. A 1D-2D PCSWMM model was developed to simulate flooding in Kissena Park under six scenarios, varying both infrastructure conditions and trunk sewer boundary conditions. The baseline scenario represented current conditions during Hurricane Ida, while subsequent scenarios isolated individual flood mechanisms using modified trunk sewer boundary conditions. Modeling results suggest that upstream trunk sewer surcharging accounted for over 75% of total flood volume, making it the dominant driver of inundation during Hurricane Ida. Building-scale drainage systems contributed no flooding, and local pipe networks at the block scale accounted for less than 25% of total flood volume. Simulating a hypothetical condition in which all existing buildings were retrofit with on-site detention volumes and orifices to restrict discharge, as required by New York City's Unified Stormwater Rule, new overflow pathways were introduced when downstream systems were at capacity. This shifted some flood burden to the building scale but resulted in a small overall decrease in flood volume due to additional storage. This research study is one of the first to explicitly consider the role that distributed local-scale drainage infrastructure like roof drains, detention tanks, and curb inlets can play in determining and/or mitigating flood patterns under intense precipitation conditions, as will become more frequent under climate change. Crucially, the findings demonstrate the limitations of local drainage systems retrofits and underscore the need for integrated, catchment-wide approaches to urban flood resilience. The modeling framework offers a replicable method for diagnosing urban flood pathways and informing the design of more adaptive stormwater systems in other settings. Future work should explore how coordinated infrastructure strategies from neighborhood to catchment scales can mitigate flooding under future climate conditions.

Characterizing the mechanisms of urban flooding during cloudburst rainfall events

Files and links (1)

Abstract

Metrics

Details

Characterizing the mechanisms of urban flooding during cloudburst rainfall events

Files and links (1)

Abstract

Metrics

Details

Drexel University Social media