Via New York Times, a look at New York City’s flooded future:

New York’s adaptation is a matter of survival. Climate experts have recommended several strategies. The city could increase its ability to absorb water, converting wide areas of asphalt and concrete to green space. It could fortify by building barriers along its shores, possibly even a gate around the harbor. Or it could retreat, relocating people out of the most hazardous regions.

The city will most likely have to embrace all three approaches in some form.

Sponge City

New Creek Bluebelt, Staten Island

In Staten Island, waterways have been restored and connected, adding parkland and reducing flooding in nearby neighborhoods. Erin Schaff/The New York Times

New York is experiencing extreme rainfall events with increasing frequency and intensity, according to a 2024 study in Nature.

Since 1970, the city’s stormwater system has been built to handle up to 1.75 inches of rain per hour. Hourly precipitation recorded by Central Park’s rain gauge didn’t exceed this limit until 1995. It’s been eclipsed in three of the last five years.

One major problem is how little of that rainfall is absorbed or stored before reaching the stormwater system. A whole suite of solutions focuses on building and expanding the city’s capacity to do so.

Understanding New York’s historical environment is crucial to imagining a more resilient urban future, one based on the city’s past topography, according to Eric Sanderson, a landscape ecologist and vice president for Urban Conservation Strategy at the New York Botanical Garden and the author of “Mannahatta: A Natural History of New York City.”

“I was trying to imagine a configuration of the landscape that could work with the understanding of climate change at the time,” Sanderson said of his book. “Part of that is restoring streams, wetlands and agricultural lands, connecting the urbanized parts of the city, and depaving a lot of what we have.”

He and a team of researchers have spent years reconstructing the past ecological landscape of the city, producing data that they hope will inform its future.

Rain gardens, curbside planted pits designed to siphon water away from drainage systems, and permeable pavement are already turning streets and sidewalks into sponges. And as part of its Cloudburst program, the city is designing parks and public spaces to flood intentionally, enhancing their innate ability to act as natural catch basins. The first to be completed, a basketball court in South Jamaica, Queens, recently opened.

But these initiatives are in their infancy. Only a handful of Cloudburst sites have been identified, and the need is most likely far greater: Sanderson and his team mapped out 540 potential locations.

Policymakers have offered several incentives to private property owners, making it easier for real estate developers to install green infrastructure. Similarly, waterfront properties above a certain size are now required to provide stormwater solutions.

Sewer and storage upgrades are also on the table. In Gowanus, Brooklyn, Department of Environmental Protection engineers are constructing an eight-million-gallon underground tank, redirecting water that would otherwise overwhelm the system during heavy rainstorms and cause combined sewer overflows into the Gowanus Canal.

Then there’s daylighting, in which onetime waterways, covered by buildings, pavement and landfill, are unearthed and restored, allowing floodwater to go elsewhere.

A project at Tibbetts Brook in the Bronx will test the concept. Concrete and other artificial materials will be removed to reroute water aboveground and into a dedicated underground pipe, reducing sewer overflow that ends up in the Harlem River.

A more dramatic example of leveraging the city’s natural landscape is the successful Bluebelt project in Staten Island, which strings together streams, ponds and wetlands — some natural, some engineered. It has already reduced flooding in parts of the borough.

But for greater effect, the city will have to rapidly expand this work to feasible locations. “Our imaginations have not caught up to what nature can and will do,” Sanderson said.

On a recent tour of the Staten Island Bluebelts, Rohit Aggarwala, the commissioner of the New York City Department of Environmental Protection, said the agency had listed 86 “priority areas” citywide for flood mitigation. “We’re asking, ‘What is the solution for this specific place?’” he said.

That work has its hurdles, though, and not every part of the city is as spacious as Staten Island. A major overhaul of local sewer capacity in Bushwick, Brooklyn, for example, will cost $390 million and take years. Expect disruption, Aggarwala said: “The residents will be less happy when they find out how long Knickerbocker Avenue will have to be ripped up.”

But for too long, he added, the city’s work was not focused enough on the future: “We have to build for 2075, not 1975.”

Walled City

Rockaway Beach, Queens

Under the sand dunes, a seven-mile wall of steel, concrete and stone provides protection from storm surge and beach erosion. Erin Schaff/The New York Times

The challenges of fortifying the coast against storm surges are deeply informed by the same geographic features that helped New York grow: It’s a cluster of islands, with a large harbor at the mouth of an ocean.

After Hurricane Sandy, the U.S. Army Corps of Engineers developed and assessed different options for protecting the New York-New Jersey Harbor region from future storm surge.

A burnt orange shading covering large parts of a map of the city and New Jersey, mainly on the edges.

First, they estimated the area at risk from storm surge in 2095, using a moderate projection of sea level rise.

A black line appears on some parts of the borders of New York and New Jersey.

After a cost-benefit analysis, the Army Corps tentatively selected an option that would include a series of barriers strategically placed to protect certain areas.

A burnt orange shading appears on parts of the coastline, sometimes overlapping with a black line.

Though it would cost an estimated $53 billion and take 14 years to construct, this proposal would leave 37 percent of the area at risk unprotected, and potentially affect waterfront views.

A view from a grassy shore of the Oosterscheldekering, a large barrier stretching toward a body of water.

A more ambitious option would include a huge storm surge barrier with retractable sea gates, stretching over six miles across the mouth of the harbor. A similar barrier has protected the Netherlands since 1986.

The Oosterscheldekering in the Netherlands

A pastel green shading on a map covering large stretches of New Jersey and New York City’s coastline.

This approach would result in 96 percent of the study area being protected, but would come with a price tag of $119 billion, according to the Army Corps of Engineers’ estimate.

The New York Times

It’s worth noting that opinions vary on almost every aspect of the Army Corps’ plans, including the actual amount of protection achieved, its environmental effect, timelines and price tags.

Still, some projects have come to fruition. Along the Rockaway Peninsula, where Hurricane Sandy slammed beachfront communities, the Army Corps built sand dunes that double as seawalls. On Staten Island’s South Shore, which was also devastated by the storm, construction started this year on a $2.3 billion coastal flooding protection project, with the federal government picking up most of the cost.

In Lower Manhattan, East River and Wagner Parks have been raised so residents there are protected from another Sandy, at least in the near future. Similar work is underway at nearby Battery Park. (Not incidentally, all three parks are built partly or entirely on landfill.)

The first flood gates have emerged on the East Side, designed to clamp into place when a storm is in sight. Will that be enough?

“It feels a little bit like we’re tinkering,” said Kate Orff, the founder of SCAPE, a landscape architecture and design firm. “Is it possible to have all the solutions at once? I’m not sure.”

Orff has been battling with the how and when for some time. Her project on Staten Island, called “living breakwaters,” submerged stone and concrete off 2,400 feet of coast. The marine life that has returned help break waves and stifle erosion — a natural wall.

“True, successful adaptation is something that’s hard to recognize, applaud and see,” she said in her downtown office, with the East River behind her. “It’s avoided damage, trauma and loss. Adaptation is, in a sense, invisible.”