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September 11, 2017 (Source: University of Bonn) - The East Coast of the United States is threatened by more frequent flooding in the future. This is shown by a recent study by the Universities of Bonn, South Florida, and Rhode Island. According to this, the states of Virginia, North Carolina, and South Carolina are most at risk. Their coastal regions are being immersed by up to three millimeters per year – among other things, due to human intervention. The work is published in the journal Scientific Reports by the Nature Publishing Group.

Cities such as Miami on the East Coast of the USA are being affected by flooding more and more frequently. The causes are often not hurricanes with devastating rainfall such as Katrina, or the recent hurricanes Harvey or Irma. On the contrary: flooding even occurs on sunny, relatively calm days. It causes damage to houses and roads and disrupts traffic, yet does not cost any people their lives. It is thus also known as ‘nuisance flooding’.

And this nuisance is set to occur much more frequently in the future. At least researchers from the Universities of Bonn, South Florida, and Rhode Island are convinced of this. The international team evaluated data from the East Coast of America, including GPS and satellite measurements. These show that large parts of the coastal region are slowly yet steadily sinking into the Atlantic Ocean.

“There are primarily two reasons for this phenomenon,” explains Makan A. Karegar from the University of South Florida, currently a guest researcher at the Institute of Geodesy and Geoinformation at the University of Bonn. “During the last ice age around 20,000 years ago, large parts of Canada were covered by an ice sheet. This tremendous mass pressed down on the continent.” Some areas of the earth’s mantle were thus pressed sideways under the ice, causing the coastal regions that were free of ice to be raised. “When the ice sheet then melted, this process was reversed,” explains Karegar. “The East Coast has thus been sinking back down for the last few thousand years.”

University of Bonn News Release

Scientific Reports Journal Article