– Large parts of the East Coast of the United States are sinking “slowly but surely.”
Densely populated cities such as New York are also affected. Not only is the risk of flooding there increasing, but also partly dilapidated infrastructure – buildings, pipelines, roads, railway lines and even the runways of large airports are at risk.
Year after year, sea levels rise and flood risks increase for coastal areas and their populations around the world. A study now shows that at the same time, large swaths of land along the East Coast of the United States are sinking — in some cases dramatically.
Densely populated cities such as New York, Baltimore and Norfolk were also affected. There, land movement not only increases the risk of flooding, but also threatens sometimes crumbling infrastructure – buildings, pipelines, roads, railway lines and even large airport runways.
“The problem is not just that the Earth is sinking,” explains lead author Leonard Ohnen of Virginia Tech in Blacksburg. “The problem is that hotspots in flooded lands directly overlap with population centers and infrastructure.” The geologist and his colleagues give examples in the magazine.PNAS Association» New York's two major airports, JFK and LaGuardia, where the annual drop rate reaches more than two millimeters.
For the entire East Coast of the United States, the team assessed ground motions along a 100-kilometer-wide strip using radar measurements from satellites for the period 2007 to 2020. The results: Large parts of the region are sinking by more than 2 millimeters per year, and some – as much as 3,700 per square kilometer – by more than 5 millimeters, and in some places more than 10 millimeters. In New York, Baltimore and Norfolk, the rate is mostly between one and two millimeters per year. The main causes are subsoil pressure, groundwater extraction and mining.
The decline, combined with rising sea levels — currently about 4 millimeters per year — could triple the risk of flooding in some areas within a few decades, the group wrote. Even if there is no rise in sea levels, continued land subsidence in some coastal areas could lead to irreversible flooding and more regular flooding.