Ida's Torrential Flooding Highlights Calls For More MTA Climate Change Resiliency

Upper West Side NY

22 September, 2021

5:32 PM

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Columbia Daily Spectator BY KATHERINE NESSEL SEPTEMBER 21, 2021 In the span of an hour, the remnants of Hurricane Ida on Sept. 1 transformed New York City's streets into rivers. With street drainage systems stressed beyond their limits, excess water cascaded into the subway tunnels. According to tweets by the MTA, northbound 1 trains began bypassing 145th Street around 9:30 p.m. due to excessive flooding. Between 10 and 11 p.m., trains on the 1 line and across the city were fully suspended. The 1 train resumed service through Morningside Heights around 9 a.m., but service was extremely limited for the entire day. Ida caused the fourth weather-related full system closure in the subway's history and the first unplanned one. Historic for its rainfall rates, the remnants of Ida broke the one-hour city rainfall record set just 10 days prior during Hurricane Henri, with 3.15 inches of rain within an hour. As intensifying downpours like these become increasingly common in New York, climate scientists have been pushing the MTA to adapt to the climate crisis. "Our climate has really changed, and these rain bombs, these heavy rain events, our city has not been designed to accommodate," Thaddeus Pawlowski, managing director for the Center for Resilient Cities and Landscapes at Columbia, said. Pawlowski, who previously worked under the New York City mayor's office to manage recovery from Superstorm Sandy, stressed the differences between Sandy and Ida. "The subway really needs to transform to be at home in this new environment," Pawlowski said. "There's a big focus … on some of the things that the MTA did after Sandy to really harden the infrastructure … but this rain event last week didn't necessarily impact only the flood zones, it was throughout the city and subway tunnels throughout the city." Sandy submerged the New York region in October 2012 with a 14-foot storm surge that mainly impacted subway tunnels under the East River along with low-lying stations like the South Ferry terminal of the 1 train, shuttering the system for two and a half days. The $7.7 billion budgeted for Sandy repairs has mainly gone to building floodgates for tunnels and stations and perimeter walls for rail yards. Unlike the large-scale focus of post-Sandy resiliency work, torrential rainfall necessitates attention on a smaller scale through the urban landscape. On 182nd Street in Washington Heights, students from the Washington Heights Expeditionary Learning School have been leading the push for a "Clean Air Green Corridor" to repurpose their street into a linear park. "These high school students in Washington Heights have a plan to turn the street in front of their school into a park," Pawlowski, who has served as a counselor to the students, said. "That's a great project that would not only reduce stormwater flooding, but also reduce the urban heat island effect and make a safer environment for kids to walk to school." On Friday, the street was transformed into a festival promoting the students' plan as a part of Park(ing) Day, a global event where road space is taken away from cars in favor of environmentally-friendly uses. "Part of the work in green infrastructure will be restoring some of those natural drainage systems, streams, and other ways for the water to be absorbed by the landscape," Pawlowski said. "That means more green roofs, more pervious paving, less pavement altogether; maybe a lot of our parking lots and highways and streets can transform … [to] be made of more natural materials that can hold water better rather than just shooting it off into our sewer system and then into our subways." The impact of paved surfaces like parking spaces on the urban ecosystem is significant. A 2020 study from Johns Hopkins University found that for every percentage point increase in paved surfaces, flooding magnitude rises by 3.3 percent. Given that streets constitute 27 percent of New York City's land area, adding more greenscapes to roads is a key way to lower flood risk. In July 2021, the Regional Plan Association mapped out the streetscape of the entire city to predict where flooding would occur in the rare case of an event with similar hourly rainfall to Ida—3.15 inches to 3.5 inches. Across the city, 20 percent of subway entrances were at risk of flooding, mainly due to surrounding buildings, cement, and asphalt. In Morningside Heights, many 1 train station stops fared relatively well through the storm due to their high relative elevation. The 125th Street station sits on the Interborough Rapid Transit Broadway Line Viaduct at 54 feet above street level, preventing flooding. The 116th Street station sits at an elevation of 130 feet above sea level, and its uphill position results in floodwater rushing down 116th Street toward Riverside Park instead of the station. However, even nearby stations with high elevations were not immune to flooding issues. The RPA analysis showed the 110th Street 1 train station having a high risk of flooding due to heavy rainfall. The particular microgeography, where Broadway is slightly less elevated than the surrounding landscape around 110th Street, leads water to pool along the corridor and seep into the subway tunnels. At 108 feet above sea level, flooding from storm surge is unlikely to ever impact this Morningside Heights station, yet intense downpours put wide swaths of the system at risk no matter the elevation. "I think [storm surge and torrential rainfall] have to be treated separately, [as] they affect different localities of the transportation system," professor Klaus Jacob, who has been affiliated with the Lamont-Doherty Earth Observatory for over 50 years and serves as a special research scientist, said. "And in the case of the subway system, it affects entirely different entrances and stations of the subway system, so they should be handled by the same department within the MTA, but they need to be considered separately in their nature to be effective." Jacob has many ideas for simple strategies that can mitigate the impact of rainfall. "For instance on entrances, you don't just go down into an entrance, you would first step up a couple of steps, [making] a mini levee system that surrounds this entrance," Jacob said. While events like Ida seem catastrophic beyond imagination, the MTA is aware of many ways to fix its issues yet fails to act. Jacob, who co-wrote a climate change resiliency plan for the MTA in 2008, is well aware of this reality. "I'm sure the operators of the system know exactly where the weak points are," Jacob said. "The next step is it has to go through the board of the MTA and the chair and they have to then sit down with the governor and legislature and make sure that the funding stream is there, because if it's not there from the state, the only other option would be to charge the customers." However, there is hope on the horizon. Pawlowski remains optimistic that President Joe Biden's infrastructure plan will provide funding for necessary environmental programs. "There's going to be a lot of money to create programs … to focus especially on the most adversely affected communities, largely communities of color in our urban neighborhoods, [where] we need the physical transformation," Pawlowski said. "I don't think it's a question of whether it will happen—it has to happen." Jacob is optimistic that, at least within the MTA, the bureaucracy will have another shot to effectively tackle the climate crisis in the near future. When asked whether he foresaw any progress on climate change under new New York Gov. Kathy Hochul, Jacob said, "It's too early to tell, but how can it get worse than it was under Gov. Cuomo? So it must get better." Staff writer Katherine Nessel can be contacted at [email protected]. Follow Spectator on Twitter @ColumbiaSpec. Founded in 1877, the Columbia Daily Spectator is the independent undergraduate newspaper of Columbia University, serving thousands of readers in Morningside Heights, West Harlem, and beyond. Read more at columbiaspectator.com and donate here.