A recent study published in Nature Cities has uncovered a concerning trend: 28 major U.S. cities, including New York City, Dallas, Chicago, and San Francisco, are experiencing significant land subsidence. This gradual sinking of land poses serious risks to infrastructure and the safety of millions of residents.
The research, conducted by scientists from Virginia Tech, Columbia University, and UC Irvine, utilized satellite radar technology to measure vertical land movements across these urban centers. The findings indicate that excessive groundwater extraction is a primary driver of this phenomenon. As cities draw more water from underground aquifers to meet growing demands, the land above these depleted aquifers begins to sink.
Houston, Texas, stands out as the fastest-sinking city among those studied. Approximately 42% of Houston’s land is subsiding at rates exceeding 5 millimeters per year, with some areas sinking over 10 millimeters annually. This rapid subsidence is attributed to extensive groundwater and oil extraction, compounded by the city’s clay-rich soil, which is prone to compaction.
New York City is also experiencing notable subsidence, with 10% of its land sinking. Areas like LaGuardia Airport are subsiding at rates over 5 millimeters per year. The city’s massive infrastructure, weighing approximately 1.68 trillion pounds, contributes to this downward pressure, especially in areas built on soft soils and artificial fill.
San Francisco faces similar challenges, particularly in regions constructed on reclaimed land, such as Treasure Island and areas near the airport. These zones are sinking by up to 5 millimeters annually due to soil compaction and historical land reclamation practices.
The study emphasizes that even minor land movements can have significant implications. Subsidence can lead to cracked roads, damaged pipelines, and increased flooding risks, especially in coastal and low-lying areas. Approximately 34 million people across these cities are affected, with over 29,000 buildings at risk of subsidence-related damage.
Experts urge immediate action to mitigate these risks. Recommendations include implementing sustainable groundwater management practices, enhancing infrastructure resilience, and integrating subsidence monitoring into urban planning.Without proactive measures, the gradual sinking of these cities could lead to catastrophic consequences in the face of climate change and rising sea levels.
