Why are all of America’s biggest cities sinking?

Cities sit without complaining about the landscape – a sprawling group of roads, sidewalks and buildings designed to continue for generations. But throughout the United States, urban areas are silently transformed: the Earth is drowned, a process known as a landing, to a large extent because people use a lot of groundwater and groundwater layers. The huge weight of the capital, too, presses the basic soil.

A new study published on Thursday in Nature Cities set the scale of the slow movement crisis throughout the country. Researchers used satellites to measure how height changed in the 28 most populated cities in America – including New York, Dallas and Saytel – and found that in each of them, at least 20 percent of the urban area. In 25 cities, two thirds of or more of the region rises, at rates of up to 0.4 inches each year. (In the maps below, Red refers to the areas where the landing is faster.)

The pulling of the groundwater was responsible for 80 percent of the total landing in cities. With the growth of urban areas – and since climate change is exacerbated, especially in the American West – its people and industries demand more water. In general, the study found that through 28 cities, nearly 7,000 square miles of land are declining, threatening 29,000 buildings and may affect 34 million people. The hot points include Los Angeles, Las Vegas, San Francisco and Washington, DC, “Cities that have a large number of population and buildings, we have a faster land landing rate and greater risk of damage.”

Houston has the fastest fastest in the country, 40 percent of its area, as more than five inches decreased annually, with 12 percent of its territory at a rate of twice this rate. Parts of the city have already sank several feet, as a result of decades of people who pump a lot of groundwater and a lot of fossil fuels. Houston Struggle already With floods of rain and rain storms, they worsened due to climate change, while the drop creates a decrease in all that water that accumulates.

If the urban area is sank at a uniform rate, it may not be a big problem, because all the infrastructure will move together. But the problem, as researchers find, is a “differential decline”, as the rates vary on a small scale. If one of the ends of the building sinks a quarter of an inch per year, and the other party drowns one third of one inch, then the difference will shake the stability of the building’s foundation.

Although the fall of a small part of the inch every year may not look much, the years begin to accumulate: within a decade only, the city can end with 6 inches from the lost height. Parts of agricultural areas ignored with water in California It decreased by about 30 feetAnd some places in Mexico City Drink 20 inches every year. “The decline represents a silent problem,” said researcher Dario Solano Rojas, who is studying at the National University of Mexico, but he did not participate in the new paper. “Now that the situation grows with the scarcity of water, this is like, well, we need to do something about water, and likewise, we do something about landing.”

The roads and airports, which extend for long distances throughout the landscape, are at great risk because there is a large space for differential outbreaks: The study found that the Laguadia airport in New York City penetrates five inches per year. Still worrying, Shirzaei’s Previous research The other infrastructure was examined on the eastern coast and discovered that all the ten dams measured in his team were drowning, leaving 46,000 people and 12 billion dollars in weak property. Sherzai has It was also found Coastal cities such as Charleston, South Carolina, and the areas surrounding the Chisabik Gulf penetrate five inches per year while sea levels rise in the same amount, which actually doubles immersion.

Until recently, cities lacking the exact data they needed to determine the areas that are running out, and any buildings and roads that may be in danger. “This study is really doing the work necessary to bring this house, by evaluating this throughout the country systematically, and showing how small we did not do so far to do anything about this problem,” said Roland Burgman, a geophysic scientist who studies at the University of California, Berkeley, but was not involved in the research.

The decline in the landing of water to the ground is what the scientists call the re -charging the oriental groundwater layer, which can re -nominate the Earth. Farmers in California They do this With excessive water during the rainy season so they can pump it back in times of need. “You somewhat are somewhat drawn, knowing that you can build it again over time, either through the rains that will infiltrate naturally and recharge, or by recharged the oriental groundwater layer.

Therefore, the landing is due to the poor management of groundwater supply, this is also a solution that can be solved. Sherzai said: “With land falling, in most cases, we have time,” We have inexpensive solutions, “Sherzai said.