This is because the land under Chesapeake Bay is going down

Jul 29, 2015 09:45 GMT  ·  By

Washington DC, the US capital, is slowly but surely sinking, a team of University of Vermont scientists warn in a new study in the journal GSA Today. 

The researchers estimate that, over the next century, Washington DC's elevation will drop by roughly 6 inches (about 15 centimeters), if not more.

Add to this the fact that ocean waters are rising due to melting ice sheets, and this gradual sinking of the US capital can only mean an increased flood risk.

In a report, the University of Vermont researchers explain that the reason Washington DC is sinking is that the land under Chesapeake Bay is too going down.

“New research confirms that the land under the Chesapeake Bay is sinking rapidly,” they write.

“This falling land will exacerbate the flooding that the nation’s capital faces from rising ocean waters,” they specialists go on to explain.

Not much can be done to stop Washington DC from sinking

The rapid sinking of the land under Chesapeake Bay has nothing to do with human activities such as groundwater withdrawals. Rather, this phenomenon is entirely nature-made.

Writing in the journal GSA Today, the team explains that, during the last ice age, an ice sheet measuring as much as 1 mile (1.6 kilometers) in thickness covered a large part of North America, stretching all the way to Long Island, NY.

Being quite heavy, this ice sheet pushed down on Earth's crust and mantle, deforming local geography. Plainly put, the massive block of ice caused land under it to sink and land south of it, the Chesapeake Bay region included, to bulge up in response.

The ice sheet began to melt some 20,000 years ago. Now that it is completely gone, the land under Chesapeake Bay is at long last popping back in its rightful place, dragging Washington DC with it.

“Land in this area, pushed up by the weight of a prehistoric ice sheet to the north, has been settling back down since the ice melted,” the University of Vermont researchers explain the mechanisms that are at play.

Flood risk can nonetheless be mitigated, the team reassures

There might not be a way to keep the land under Chesapeake Bay and Washington DC from sinking, but this does not mean that nothing can be done to safeguard the US capital against future flood events.

As mentioned, the increased flood risk discussed by the University of Vermont team in their report depends not just on inevitable shifts in local landscapes but also on rising ocean waters, in turn caused by man-made climate change and global warming.

Hence, one sure way to reduce the risk of flooding in Washington DC would be to put a leash on these phenomena. Needless to say, building infrastructure designed to contain ocean waters would also come in handy.