The city’s sinking into the ground, due to the weight of its skyscrapers, may affect the risk of flooding as sea levels continue to rise.
New York’s towering buildings impact the entire city. The total weight of the skyscrapers, estimated by American researchers at 764 million tons, leads to a subsidence of the city, which is sinking, according to them, from one to two millimeters per year into the ground.
This is only an average: the south of Manhattan or even certain districts of Brooklyn or Queens are sinking more quickly than others, up to twice as fast, according to these researchers from the University of Rhode Island. These disparities are linked to the nature of the soil, a mixture of clay, sand and silt, according to the study published in early May in the scientific journal Earth’s Future.
This phenomenon is scientifically called subsidence. It is a subsidence of the earth’s crust, due to loads that are added to this crust. Here, the researchers focused on the “cumulative mass and downward pressure exerted by the built environment” of the Big Apple, although the causes of subsidence are multiple.
Sea level rise
Storms and extreme weather events, which are intensifying and multiplying due to climate change, mean that New York is, like many other cities located on the water’s edge, prone to flooding, especially as the level of the sea continues to rise, parallel to the subsidence of the city.
The lower part of Manhattan is already located between 1 and 2 meters below sea level, which makes the area particularly exposed to the risk of submersion. Hurricane Sandy brought seawater into part of the city in 2012, and more recently, Storm Ida massively flooded the Big Apple in 2021, killing more than forty people.
Seawater also damages the structure of buildings, which is another risk for the city’s 8 million inhabitants.
“Common Global Challenge”
The researchers also clarified in their study that New York is “emblematic of expanding coastal cities around the world that are observed subsiding”, and this example represents the “common global mitigation challenge” in the face of a increasing risk of flooding.
“As coastal cities grow around the world, the combination of increased building density and rising sea levels leads to increased flood risk,” the researchers explain.
They therefore draw attention to the risk associated with the construction of large buildings by the sea, river or lake, which may contribute to the risk of future flooding. Cities like Rio de Janeiro, Venice, San Francisco, Amsterdam or Jakarta are also threatened.
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2023-05-22 13:17:42
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