This past October, New York City was struck by a sudden, intense torrential storm that meteorologists did not predict; the total rainfall—about one to three inches—was projected to occur gradually throughout the entire day. Instead, it fell in a short 20-minute burst, according to The New York Times. Several daily rainfall records across the city were shattered, such as Central Park’s record, where the 1.83″ total broke the daily record of 1.64″ from 1917, as stated by CBS. Flash floods swept through the streets, taking lives, damaging property, stranding pedestrians in several feet of water and affecting the everyday lives of countless NYC residents. Though intense and unexpected, these floods fit into a growing climate-related rainfall trend that has been reshaping the way we live, challenging the urban infrastructure that can no longer withstand the city’s changing weather.
New York’s Climate Complications
Scientists, officials and everyday New Yorkers have begun to notice alarming trends in flooding across New York. “The four most intense storms in New York City’s history have taken place in the last four years,” explained NYC Department of Environmental Protection (DEP) Commissioner Rohit Aggarwala in a CBS interview this year. A 2024 study, “Increasing extreme hourly precipitation risk for New York City after Hurricane Ida,” explains that before the 1990s, the strongest local storms barely reached 1.5 inches of maximum hourly rainfall. Since then, many storms have surpassed 1.8 inches, with Hurricane Ida’s storm standing out among the rest at 3.5 inches in 2021.
As atmospheric temperature continues to rise, the airholds more moisture, allowing storms to unleash significantly larger amounts of rain in shorter periods, according to Climate Central. Therefore, the flash flood that occurred a month ago wasn’t an environmental anomaly. As climate change intensifies, floods will only become more common in New York.
The Combination of Outdated Infrastructure and a New Climate Leads to Failure
“Any flooding in cities, like NYC, are a function of how much rain falls and where it falls,” said Poly Prep Science Faculty Clark Richter. “For the recent NYC floods, a lot of rain fell at a fast rate, and it fell on impermeable surfaces, like concrete sidewalks, asphalt roads and waterproof rooftops.” Water that cannot be absorbed into the ground only has one place to go: streets, basements, subways and other exposed areas.
“The city’s sewer system is designed to accommodate about 1.75 inches of rainfall per hour,” reported DEP Commissioner Rohit Aggarwala in the aforementioned CBS interview; they were made for a time when that was exceeding the rate of rainfall, guaranteeing minimal flooding at most, according to a 2024 study. However, as climate change has increased rainfall in the metropolitan area, sewer designs have not changed. In October’s storm, there was “one inch of rain in 10 minutes,” relayed Aggarwala. “That’s about six inches per hour…crews work to clear the city’s 150,000 catch basins ahead of each storm, but the rain still can sweep leaves into clean grates.”
This combination of higher rainfall, excessive impermeable surfaces, an outdated rainfall collection system and the hindrance of those systems makes New York City an environment susceptible to floods during storms.
Poly Prep: A Local Perspective on the Floods
Flash flooding has also affected the Poly Campus, particularly in the science building. In the 2023-2024 school year, Poly Prep Science Faculty Madeline Carsello recalled a “day when the rain…was so heavy that [the school] actually cancelled [the day] early. In the science building, there was probably [six inches] of water at the base of the [first floor’s] staircase before I went to school. All the classes that were on the first floor had to move to different classrooms.”
This year brought a similar situation. Poly Prep Science Faculty Jill Dunscomb shared that while “we got our students out [of the lab] before [the rain] was on the floor” during a recent storm, “10 minutes later, there was a foot of water in [the] staircase” caused by the low elevation and the delayed employment of the floodgates.
Both Dunscomb and Carsello expressed gratitude that the damage was minimal. Carsello said, “I definitely feel fortunate to have the floodgates and having this faintness around the situation; we’re fortunate enough to be able to [say], ‘oh, ha ha, that’s crazy,’ rather than it being a serious danger to anyone.”
Impacts and Damages on New Yorkers
Flash floods have cost New Yorkers $2.5 billion in property damages, and typical floods have cost $1.2 billion, according to the Office of the New York State Comptroller. The human toll has also been grave—two men died tragically after getting trapped in flooded basements this past October, as stated by The New York Times, and countless other lives have been taken in previous flash floods and storms. Public transportation, such as the subway and buses, has also come to a halt during flash floods, leaving many commuters stranded.
What is Being Done about New York City’s Vulnerability to Floods?
In response to this growing problem, many adaptive protective measures are currently being installed across the five boroughs, from floodgates and floodwalls to elevated parklands and coastal barriers, according to the NYC government’s The East Side Coastal Resiliency Project. These solutions all perform the same function—stopping the water from spreading to important areas.
To address water accumulation on the streets, certain green infrastructure installations such as rain gardens, infiltration basins, green roofs, porous pavement and green streets are also being experimented with—all of which help to absorb stormwater and are part of an expanding environmental initiative from the NYC government’s Environmental Protection sector. “Designing infrastructure to better allow drainage in any form can make the city more resilient to rainfall events,” shared Richter. “I’m particularly fond of [rain gardens], tree beds that have a lot of plants growing in them…The plants—and all their roots—make it easy for water to penetrate down into the ground at rain gardens rather than running across the concrete to flood somewhere else.” Ultimately, as rainfall intensifies and flash floods become more frequent, these measures represent New York’s best chance to adapt and withstand its changing climate.
