One of the 10 Fastest-Sinking Coastal Cities is in the U.S., Study Shows
Have you ever heard of “land subsidence”? For residents in certain coastal cities, land sinkage is a pressing issue.
What causes sinking land, you ask? In the ten cities highlighted in this list, the phenomenon has less to do with natural climate cycles and almost everything to do with human activity: Buildings that are too heavy for the ground to support and people extracting too much groundwater are the main culprits.
Mindfully American gathered data that was featured in Nature Sustainability to put together this list of the world’s fastest-sinking coastal cities.
Sinking Land
To determine which coastal cities are sinking the fastest, researchers used satellite radar. They chose the 48 largest coastal cities in the world, honing in on ten that are at especially high risk of fast rates of land sinking.
That said, any land subsidence is bad; there are many cities not on this list that are also experiencing sinking, albeit at a slower rate. The United States is no different. One American city is on this list, but many more have land subsidence issues.
Two metrics went into this land subsidence study: peak velocity and median velocity, both of which scientists measured in millimeters (mm) per year. The higher the number, the faster the rate of sinking. They based the final rankings on the peak velocity, which is why you’ll see variations in the median velocity in the following rankings.
Zeroing in on Tianjin
Tianjin has among the most aggressive rates of land subsidence among major coastal cities in the world. Experts point their fingers at geothermal well drilling, which started in 1979. Since then, locals have drilled over 70 wells, and the result has been devastating.
The silver lining? Data shows that the rate of land subsidence is declining thanks to efforts locals have taken to reverse the issue.
From All Angles
According to the United States Geological Survey (USGS), the excessive removal of subsurface water is one of the most common causes of land subsidence in the U.S. It’s far from the only culprit, though.
Other things that can contribute to land subsidence are:
- Aquifer-system compaction
- Organic soil drainage
- Underground mining
- Hydrocompaction
- Natural compaction
- Thawing permafrost
- Sinkholes
Sinking America
Houston isn’t the only area in the U.S. suffering from land subsidence. Over 17,000 square miles of American soil have sunk due to human-led causes. That’s approximately the size of New Hampshire and Vermont combined.
Arid Southwest areas and humid Southern states are often at the highest risk of land subsidence when humans fail to control the extraction of groundwater and perform other practices that cause land to sink.
Silver Lining
Land subsidence is a threat to citizens across the globe, but it isn’t all gloom and doom. When excessive groundwater extraction is a leading cause of sinking land, cities can put water back into the ground. The process of doing so is called managed aquifer recharge.
Case in point? Coachella Valley’s land experienced as much as a 2-foot sink between 1995 and 2010. However, by using water from the Colorado River, golf courses, farms, and other non-drinkable water sources, conservationists were able to slow subsidence rates by as much as 75% in many areas. In the northern part of the valley, the land even rose 2.3 inches.
Most and Least Visited States
Data company YouGov compiled the states Americans have visited the most and least. How many of the states on their list have you been to?
Most and Least Visited States by Americans
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