Produced by: Tarun Mishra
Designed by: Manoj Kumar
A comprehensive study conducted by NASA's Jet Propulsion Laboratory and Rutgers University has unveiled a concerning phenomenon in New York City—sinking and rising land, influenced by a complex interplay of human activities and natural geological processes.
This groundbreaking research employed cutting-edge interferometric synthetic aperture radar (InSAR) technology, allowing scientists to meticulously scrutinise vertical land motion in the New York metropolitan area over the span of seven years, from 2016 to 2023.
A significant revelation from the study is the role of human interventions. It underscores that extensive human-made alterations, like land reclamation and landfill construction, have rendered the ground beneath certain buildings more susceptible to compression. This, in turn, contributes to the city's gradual subsidence.
Beyond human factors, the study illuminates the enduring impact of natural processes stemming from the last ice age. As the Earth's mantle slowly adapts to the removal of the ice sheet that once blanketed regions including New England, the land beneath New York City, situated just beyond the ice sheet's edge, is subsiding.
On average, the New York metropolitan area is experiencing a subsidence rate of approximately 1.6 millimetres per year. However, the study enables pinpointing specific neighbourhoods and iconic landmarks sinking at rates exceeding this average.
Examples include LaGuardia Airport's runway 13/31, which is sinking at a rate of 3.7 millimetres per year, and the renowned Arthur Ashe Stadium, descending at a rate of 4.6 millimetres per year.
The study's findings also unveiled unexpected pockets of uplift. In East Williamsburg, Brooklyn, and Woodside, Queens, land is ascending, with rates measured at 1.6 millimetres and 6.9 millimetres per year, respectively.
While the sinking phenomenon is relatively well understood, the reasons behind the uplift are still under investigation. Among potential factors, groundwater pumping and the use of injection wells for treating polluted water are being explored as potential contributors.
These findings hold profound implications in the context of climate change. Rising global sea levels are causing more frequent nuisance floods and destructive storm surges worldwide. Thus, the precise mapping of vertical land motion presented by this study is invaluable for flood prediction and urban planning.
As New York City intensifies its efforts to bolster coastal defences and fortify critical infrastructure in response to sea-level rise and climate change threats, this study's high-resolution data on land motion serves as a critical tool to inform and enhance the city's resilience measures.