The remnants of Hurricane Ida pummeled New York City on Wednesday night, flooding homes, roads, stores, and subways across the five boroughs with rainfall totals meteorologists expected to see once every thousand years. The cloudburst set a new one-hour rainfall record in Central Park—breaking the record Tropical Storm Henri set just two weeks before. At least nine in the region are dead from the flooding.
It was the first-ever flash flood emergency in the nation’s largest city, but it won’t be the last. Climate change is making more intense rainstorms more frequent, particularly in the Northeast, and the expectations that such a storm would occur once a millennium are now obsolete.
To some extent, our options for how to bottle four inches of rain an hour in a densely populated urban area are limited.
But we can work to mitigate the effects. In May, New York released its first-ever analysis of how to prepare for stormwater flooding. Goal No. 1: “Inform the public about flood vulnerability from extreme rain.” Mission accomplished. Unfortunately, the rest of the report is a bunch of policy gibberish, such as the conclusion that the city “will expand upon the modeling completed for this effort and continue developing a citywide hydrologic and hydraulic (H&H) model to better estimate runoff flow for various climate scenarios to be included in the drainage planning process.” OK.
Here, in plain English, are some Ideas that New York City can employ tomorrow to mitigate the effects of extreme rainfall.
1. Plant more trees
This is basic, but obvious. Between the rooftops and the roads, New York is mostly impervious surface, which creates high degree of flooding relative to rainfall. The city should replace some of that pavement with green infrastructure, which holds water where it falls, relieving stress on sewers and storm drains. New York City has new, strict requirements for how developers must deal with stormwater runoff, and the mayor’s task force wants a green roof tax credit. Fine. But the biggest piece of the pie, by far, are the 6,300 miles of streets the city controls. That’s where the city should invest in planting absorbent grasses, bushes, and trees, which can reduce runoff by a factor of 10 compared to asphalt. Tearing up some roads is worth it.
2. Pick up the trash
The city boasts it has spent $4 billion on sewers over the past 10 years and will double that spending in the next decade. But sewers only work if the water can get to them, and here New York has a very simple and obvious problem: The unusual practice of storing trash on the sidewalk creates thousands of ready-made obstacles that block storm drains and create lakes in places that ought to drain properly. Low-lying areas need better drainage, which may require bigger pipes—or simply receptacles to hold trash so that it doesn’t gum up the works. (The MTA doesn’t clean its drains either.)
3. Protect the subway
According to an analysis by the Regional Plan Association, one in five subway entrances is at risk of stormwater flooding. The City of New York has a map of where extreme stormwater flooding is expected to happen. Protecting entrances and air vents that lead to the subway should be a no-brainer investment for a city where millions of people rely on trains every day. But of the $10 billion allocated by the Federal Transit Administration for the New York City region after Superstorm Sandy, less than half has been spent. Now that Andrew Cuomo isn’t in charge anymore, maybe Gov. Kathy Hochul can figure out: What are we waiting for? Entrances and grates in vulnerable locations should be raised above street level to keep stormwater in the curb where it belongs.
4. Legalize basement apartments
It’s likely that more than 100,000 New Yorkers live in basement apartments, which puts them in serious danger during extreme rainfall events. Many of those apartments are illegal, which makes it hard for tenants to complain about unsafe conditions or seek redress when problems occur—and difficult for homeowners to finance improvements. At least two people were killed on Wednesday as floodwater collapsed a wall in their basement apartment. But there’s been little urgency in Albany to legalize these dwellings.
5. Work fast
Basement apartments and subway floodproofing are both example of issues that have been on the radar in New York City for a long time. Legalizing apartments is free. Keeping the subway dry has been funded by Congress. But almost 10 years after Sandy showed everyone how vulnerable New York was, little has been done. This sense of inertia governs a number of issues in New York City, from bike lanes to homeless shelters, but it doesn’t need to be that way. The city can rip up the streets and plant marsh grasses in the gutters tomorrow. It can install trash containers in the curb lane. The next rainstorm isn’t going to wait for the community board, and it’s certainly not waiting 1,000 years. Bill de Blasio has four months left in office and he should make the most of them.
