The land in New York are Sinking and Rising at varied speeds as a result of both natural and human forces, according to researchers utilising space-based radar. A few areas are growing.
New York are Sinking and Rising
Scientists have discovered that various parts of the New York City metropolitan region are sinking and rising at various rates as a result of things like land use patterns and long-gone glaciers. Although the elevation changes are minute—a few inches per year—they might increase or decrease the local flood risk brought on by sea level rise.
The new study was published on September 27 in Science Advances by a team of researchers from NASA’s Jet Propulsion Laboratory (JPL) in Southern California and Rutgers University in New Jersey. The team analyzed upward and downward vertical land motion – also known as uplift and subsidence – across the metropolitan area from 2016 to 2023 using a remote sensing technique called interferometric synthetic aperture radar (InSAR). The technique combines two or more 3D observations of the same region to reveal surface motion or topography.
New York are Sinking and Rising
Mapping vertical land motion across the New York City area, researchers found the land sinking (indicated in blue) by about 0.06 inches (1.6 millimeters) per year on average. They also detected modest uplift (shown in red) in Queens and Brooklyn. White dotted lines indicate county/borough borders.
Credit: NASA/JPL-Caltech/Rutgers University
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Factors Influencing Land Motion
The majority of the motion they saw took place in regions where previous alterations to the Earth’s surface, like land reclamation and landfill development, made the ground looser and more compressible beneath future structures.Natural processes that go back thousands of years to the most recent ice period also contribute to some of the motion. Most of New England was covered by a massive ice sheet around 24,000 years ago, while upstate New York’s Albany was covered by an ice wall more than a mile high. Since then, the Earth’s mantle has been gradually readjusting, kind of like a flexed mattress. Now slipping back down is New York City, which was lifted just outside the border of the ice sheet.
Detailed Findings and Impacts
The average amount of subsidence in the metropolitan area, according to the researchers, was 0.06 inches (1.6 millimetres) a year, or roughly equal to how much a toenail grows in a month. With the help of sophisticated data processing methods and the radars on the ESA Sentinel-1 satellites, they were able to map the movements in great detail and identify specific neighbourhoods and landmarks, down to an airport runway and a tennis stadium, that are subsiding more quickly than usual.
New York are Sinking and Rising
The team pinpointed hot spots: left, runway 13/31 at LaGuardia Airport in Queens, is subsiding at a rate of about 0.15 inches (3.7 millimeters) per year; right, part of Newtown Creek, a Superfund site in East Williamsburg, Brooklyn, is rising unevenly by about 0.06 inches (1.6 millimeters) per year.
Credit: NASA/JPL-Caltech/Rutgers University
“We’ve produced such a detailed map of vertical land motion in the New York City area that there are features popping out that haven’t been noticed before,” said Brett Buzzanga, the paper’s primary author and a postdoctoral researcher at JPL.Tracking local elevation changes and relative sea level can be crucial for flood mapping and planning, according to David Bekaert, a JPL scientist and the project’s primary investigator. This is especially important because global ocean levels are rising due to Earth’s changing climate, which makes nuisance floods more often and exacerbates destructive storm surges.Tracking local elevation changes and relative sea level can be crucial for flood mapping and planning, according to David Bekaert, a JPL scientist and the project’s primary investigator. This is especially important because global ocean levels are rising due to Earth’s changing climate, which makes nuisance floods more often and exacerbates destructive storm surges.
Significant Hotspots
The scientists found two significant subsidence hotspots in Queens that were close to landfills. LaGuardia Airport’s runway 13/31 is one that is sinking at a rate of roughly 0.15 inches (3.7 millimetres) per year. The scientists pointed out that a $8 billion refurbishment of the airport is being done, in part to prevent floods brought on by the Atlantic Ocean’s rising seas. They also noted Arthur Ashe Stadium, which needed to build a lightweight roof during renovations to lessen its weight and subsidence since it is sinking at a pace of roughly 0.18 inches (4.6 millimetres) each year.
New York are Sinking and Rising
The southern portion of Governors Island, which was constructed on 38 million square feet (3.5 million cubic metres) of rocks and dirt from early 20th-century subway excavations, as well as areas close to the water in Coney Island in Brooklyn and Arverne by the Sea in Queens, which were constructed on artificial fill, are some other subsidence hotspots. In suburban New Jersey, where Route 440 and Interstate 78 pass over former fill sites, as well as on Rikers Island, which was enlarged to its current size through landfilling, similar amounts of sinking have been noted.
The researchers also discovered previously unknown uplift in Woodside, Queens, which increased 0.27 inches (6.9 millimetres) per year between 2016 and 2019 before stabilising, and East Williamsburg, Brooklyn, which rose by roughly 0.06 inches (1.6 millimetres) per year. Groundwater pumping and injection wells used to remediate contaminated water may have played an impact, according to co-author Robert Kopp of Rutgers University, but more research is required. Kopp expressed interest in the possibilities of utilising high-resolution InSAR to monitor these kinds of transient environmental changes brought on by uplift.
High-resolution estimations of land motion, according to the scientists, can help cities like New York, which are investing in coastal infrastructure and defences due to sea level rise.
Future Monitoring and Projects
New York are Sinking and Rising
Surface displacement information over North America will be included in a future data product from the JPL-led OPERA (Observational Products for End-Users from Remote Sensing Analysis) project. It will use InSAR data from Sentinel-1, an ESA mission, as well as the planned NISAR (NASA-Indian Space Research Organisation Synthetic Aperture Radar) project, which is scheduled to launch in 2024, to achieve that. Scientists will be able to more effectively track changes associated with natural hazards as well as vertical land motion thanks to information from OPERA.
Reference: “Localized uplift, widespread subsidence, and implications for sea level rise in the New York City metropolitan area” by Brett Buzzanga, David P.S. Bekaert, Benjamin D. Hamlington, Robert E. Kopp, Marin Govorcin and Kenneth G. Miller, 27 September 2023, Science Advances.
DOI: 10.1126/sciadv.adi8259
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