How Ida dodged NYC’s flood defenses

Problem is that we are seeing these impacts and these shifting storms more quickly and adaptations just aren't keeping up with them, says Lauren McPhillips (a Penn State University hydrologist who studies urban flooding).
McPhillips states that New York City is a leader in flood preparation. The city has been putting in permeable architecture for years like rain gardens and green roofs. It also upgraded its drainage pipes and pumps. After Sandy, these improvements were even more impressive.

In a press conference, Kathy Hochul, New York governor, stated that Sandy taught us a lot. Our coastal shorelines are now in much better condition than they were before the storms. We have rebuilt our resilience. Our streets are where we have vulnerabilities.

Sandy is a major topic in discussions about flooding in New York City. The difference in the Ida and 2012 hurricane illustrates the complicated flood threat that the city faces due to climate change. Sandy created a severe storm surge that caused the sea to rush into the city. Ida poured inches of water on the city in a very short time, a problem that no sea barriers or other coastal protections could solve.

Although New York City and the other coastal areas are more susceptible to sea-level rising, urban areas can still experience pluvial flooding. This is when rainfall causes flooding. According to Timon McPhearson of the New School, Timon McPhearson is a researcher on urban climate resilience and a member the New York City Panel on Climate Change.

Concrete and other impervious surfaces cause water to flow downhill, rather than sinking into the ground like it would in grasslands and forests. The consequences can be fatal if there is too much water.

"We must literally redesign the city in order to solve this problem." Timon McPhearson

McPhearson and other researchers helped New York City develop plans to strengthen its flood defenses. In May 2021, New York City released a forward-looking plan for stormwater resilience. It included an assessment of flood risk in the city, and suggested solutions that range from social strategies like educating local councils about flood risks to engineering techniques, such as more rain gardens and green roofs.

The city's Department of Environmental Protection is looking at plans to help areas most affected by the strongest storms. In 2018, the Cloudburst Resiliency Study was completed. It examined strategies for dealing with extreme rain events. In Queens, there were plans for pilots to install floodable park walkways and a basketball court that could hold water during major flooding.

These or other stormwater management solutions, however, would require significant funding and would take a decade to design. McPhearson states that we need to redesign the city in order to solve this problem. He expects that the cost of this project will be high, possibly in the hundreds of billions. He says that while there are some cases where the research suggests ways to protect the city from flooding, it is difficult to get the money and political will to do so.