New York is sinking: some areas are sinking faster than others

Not all landmass in New York City is created equal, according to a new study. Some are sinking much faster than others, affecting the risk of flooding as sea levels rise, reports The Washington Post.

Experts found that the runway at LaGuardia Airport, Arthur Ashe Stadium, Interstate 78, which includes the Holland Tunnel, and Highway 440, which connects New Jersey and Staten Island, are sinking more than 2 mm per year. They are sinking faster than New York City, by an average of 1,6 mm per year, according to a study published in the journal Science Advances.

“If you're an average coastal city resident, I think it's important for you to understand what the vertical component of land motion does and how it can change susceptibility to flooding, even across different areas,” said Brett Bazzanga, lead author of the study and a coastal scientist at the Lab. NASA jet propulsion.

Millimeters of land subsidence in New York may seem small by comparison, but they could make flooding worse as sea levels rise. Over the past 20 years, sea levels in Manhattan have risen by 4,4 mm per year, partly due to land subsidence, the study says. This will be fraught with serious consequences if extreme weather conditions occur: according to one of the estimates Research, about $8 billion in damage from Hurricane Sandy in 2012 was attributed to rising sea levels.

“Rising sea levels and falling land levels could cause even more damage,” Bazzanga said. “It kind of increases the background conditions that hurricanes operate on.” There is more water."

New research methodology

Nobody wants to see New York like in creepy apocalyptic films, where only Lady Liberty's torch rises above the water. It is for this reason that scientists from all over the world are studying soil and soil, the impact of global warming and trying to stop deformation processes that can lead to very disastrous consequences.

Bazzanga and his colleagues used a new technique using satellite data to obtain high-resolution measurements and compare areas. This research improves on GPS data obtained from ground-based instruments or aircraft, which can collect high-resolution but pinpoint data.

“We're showing in unprecedented detail the differences across the region and how some areas may be sinking faster than others, which could cause more flooding in some places,” Bazzanga explained. “The same thing will happen in any city.”

New York is one of several coastal cities experiencing significant subsidence. Other research showed that Norfolk and Virginia Beach, for example, are sinking by an average of more than 3,5 mm per year. Some areas around New Orleans are 40 mm a year.

The earth can sink for several reasons. In New York, this is largely due to the retreat of glaciers from the last ice age, when ice sheets weighed down the ground and caused the crust to stretch and subsidence beneath the northeastern United States. New York was on the periphery of the trough and bulged upward. As the ice sheet retreated, the land began to gradually level out, and the sunken areas began to rise, and the convex areas began to fall.

Think of these changes as if you pressed your finger on a balloon and then lifted it.

However, human activities can place additional stress on our land, causing it to sink or rise beyond these underlying natural processes. The study found that subsidence hot spots at LaGuardia Stadium, Arthur Ashe Stadium and along some roadways were former landfills. According to Bazzang, these areas “will shrink much faster than something built on stronger soil.”

Arthur Ashe Stadium was renovated with a special lightweight roof to reduce subsidence.

Somewhere it left, somewhere it arrived

The study, among other things, revealed several unexpected areas where the ground is rising. For example, in Brooklyn, the Newton Creek area of ​​East Williamsburg has seen soil rise of about 2 mm per year. The study notes that the area is undergoing a major engineering project to restore and clean up contaminated groundwater from the creek's aquifer, which could cause the ground to rise. However, rising ground can destabilize infrastructure.

Tom Parsons, a geophysicist at the U.S. Geological Survey who was not involved in the study, said he was impressed by the resolution of the authors' subsidence and uplift data.

Their findings are also consistent with what Parsons and his colleagues previously found: infrastructure built on artificial fill on or near the coast subsides at a higher rate.

According to Parsons, the study confirms the usefulness of satellite data “in helping large cities decide a variety of issues, such as where to construct large buildings, the use of artificial fill and the need to take measures to protect against future flooding.”

Scale analysis

Steven D'Hondt, a professor of oceanography at the University of Rhode Island who was not involved in the new study, added that subsidence in landfill areas may be exacerbated by the weight of buildings and runways. However, subsidence caused by this additional infrastructure weight usually stops within a few years of construction, so it is not a major factor contributing to land subsidence.

According to Bazzang, he and his colleagues plan to use an updated version of their algorithm to make available data shifts across North America, which will provide information on land subsidence and rise and can assist in flood risk determination and metropolitan planning.

“Every city in the world will benefit from such a sensitive analysis of the vertical movement of the earth within its boundaries,” concluded D'Hondt.