Critical Infrastructure Is Sinking Along the US East Coast
arstechnica.com
Up and down the Atlantic Coast, the land is steadily sinking, or subsiding. That’s destabilizing levees, roads, and airports, just as sea levels are rising.

It’s steadily sinking or subsiding, which is destabilizing levees, roads, and airports.

Unless you’re sinking into quicksand, you might assume that the land beneath your feet is solid and unmoving. In actual fact, your part of the world may well be undergoing “subsidence,” which is where the ground collapses as sediments settle or when people over-extract groundwater. New York City is sinking, too, due to the weight of all those buildings pushing on the ground. In extreme cases, like in California’s agriculturally intensive San Joaquin Valley, elevations have plummeted not by inches, but by dozens of feet.

Last year, scientists reported that the US Atlantic Coast is dropping by several millimeters annually, with some areas, like Delaware, notching figures several times that rate. So just as the seas are rising, the land along the eastern seaboard is sinking, greatly compounding the hazard for coastal communities.

In a follow-up study just published in the journal PNAS Nexus, the researchers tally up the mounting costs of subsidence—due to settling, groundwater extraction, and other factors—for those communities and their infrastructure. Using satellite measurements, they have found that up to 74,000 square kilometers (29,000 square miles) of the Atlantic Coast are exposed to subsidence of up to 2 millimeters (0.079 inches) a year, affecting up to 14 million people and 6 million properties. And over 3,700 square kilometers along the Atlantic Coast are sinking more than 5 millimeters annually. That’s an even faster change than sea-level rise, currently at 4 millimeters a year. (In the map below, warmer colors represent more subsidence, up to 6 millimeters.)

…

A few millimeters of annual subsidence may not sound like much, but these forces are relentless: Unless coastal areas stop extracting groundwater, the land will keep sinking deeper and deeper. The social forces are relentless, too, as more people around the world move to coastal cities, creating even more demand for groundwater. “There are processes that are sometimes even cyclic, for example in summers you pump a lot more water so land subsides rapidly in a short period of time,” says Manoochehr Shirzaei, an environmental security expert at Virginia Tech and coauthor of the paper. “That causes large areas to subside below a threshold that leads the water to flood a large area.” When it comes to flooding, falling elevation of land is a tipping element that has been largely ignored by research so far, Shirzaei says.

  • maynarkh@feddit.nl
    216·
    10 months ago

    This is a known phenomenon since forever. You have to work to keep infrastructure working, not just because of this, but other reasons as well. I mean, it’s like people are surprised that you have to cut the grass at an airport.

    If you come to Amsterdam, you might notice that most buildings have cellar doors. That’s not because people like cellars so much, it’s that those used to be ground level when they built it. People just built a door higher up, with some stairs leading up to them when the buildings sunk noticeably. You can also see buildings tilt. There are alleys in there, where on the ground there is around 2 and a half metres of space, but the tops of the buildings are close enough to lean out and pass things between them.

    I feel articles like this are just there to try to give excuses why the US’ infrastructure is so much behind the rest of the developed world. This is not a unique, never-before-seen problem. People were solving this exact problem for multiple times as long as the US has existed. Just think, why do you think most archaeological digs are digs? It’s not because people have a weird obsession with burying old structures.

    • MicroWave@lemmy.worldOPEnglish
      121·
      10 months ago

      Not sure I follow that the article is giving excuses.

      The article actually identifies man-made groundwater extraction as a major cause of land subsidence. On top of that, just because what Amsterdam and the Netherlands did was successful doesn’t necessarily mean it can be easily replicated in other locations. An example from the article:

      In Jakarta, Indonesia, for example, the land is sinking nearly a foot a year because of collapsing aquifers. Accordingly, within the next three decades, 95 percent of North Jakarta could be underwater. The city is planning a giant seawall to hold back the ocean, but it’ll be useless unless subsidence is stopped.

    • nicetriangle@kbin.social
      9·
      10 months ago

      Amsterdam is like that because they built it on a literal tidal floodplain reclaimed using dikes and when they put in a foundation under buildings they used wooden posts which eventually rotted away causing buildings to slump into the soft, wet earth underneath.

      The problems and geology of the eastern US with respect to sinking land are much different.

  • MNByChoice@midwest.social
    141·
    10 months ago

    over 3,700 square kilometers along the Atlantic Coast are sinking more than 5 millimeters annually. That’s an even faster change than sea-level rise, currently at 4 millimeters a year.

    Shit. In round numbers, that is a foot in 34 years (assumes a constant rate, which is unlikely.)

    • Potatos_are_not_friends@lemmy.world
      27·
      10 months ago

      Either I’m getting extremely old and becoming a boomer but 1 ft every 34 years doesn’t seem like a problem for most people.

      Maybe the companies that own coastal properties. And if anything, properties on the coast tend to be wealthy anyways. So they have the financial resources to deal with it.

      • hedgehogging_the_bed@lemmy.worldEnglish
        7·
        10 months ago

        Get down to the part where it’s happening inconstantly even across small pieces of ground. 34 years is a short time for a building foundation.

      • Xhieron@lemmy.worldEnglish
        5·
        10 months ago

        In isolation it might not be. The problem is that 1 foot drop isn’t the only thing happening. Over the same period, the sea level would be expected to rise a foot also. 2 feet is the difference between a resort and an underwater hotel lobby in many areas.

        Sure, that might only affect the rich property owners, but you can bet the Florida taxpayers will be the ones footing the bill to ensure Miami still exists for our grandchildren.

  • DrunkenPirate@feddit.de
    1·
    10 months ago

    Oh this sounds familiar for a German in Ruhr area. This area is strongly undermined by coal mines. Imagine LA with many levels of cellars under it. Down to even 1000mtrs.

    Ruhr area sunk down year on year for around 100 years now. Many buildings would get drowned by natural ground water if there wouldn’t be pumps. These pumps are supposed to run forever. It’s financed by a fund of the coal mines and called “Eternal fund” Last coal mine closed 2018.