Recent research reveals that cities like New York, Dallas, and Seattle are among those experiencing significant sinking. An analysis involving 28 urban areas in the U.S. highlights that this decline could impact around 34 million individuals.
A study published in the Journal Nature indicates that these cities are sinking at rates ranging from 0.08 to 0.4 inches annually, primarily due to groundwater extraction.
Conducted by Virginia Tech, the study utilized satellite radar measurements to produce detailed maps of land subsidence in the most populated American cities. Notably, these urban areas account for about 12% of the total U.S. population.
According to Leonard Ohanhen, the lead author of the study, even minimal downward movement of land can greatly affect the structural stability of buildings, roads, bridges, and dams. He emphasized that many small changes can accumulate over time, worsening vulnerabilities within urban systems and heightening flood risks.
A significant finding indicates that at least 20% of the urban areas studied have experienced subsidence, with about 65% of the cities affected. Specifically, cities like New York, Chicago, and Seattle sink at approximately 0.08 inches each year, while certain places in Texas, particularly Houston, show even higher rates, approaching 0.2 inches annually.
Interestingly, some localized regions are sinking faster than their surroundings, which researchers consider one of the more harmful yet visible manifestations of subsidence.
Professor Shirzaei cautioned that, unlike flood risks that can be more apparent, subsidence-related risks may stay hidden until they reach critical levels. His team assessed how varying rates of sinking could elevate infrastructure vulnerabilities. Additional cities with notable subsidence variability include Las Vegas and Washington, D.C.
Shirzaei stated that the nature of this risk means infrastructure can deteriorate over time without immediate signs until the damage becomes severe. He noted that rapid urban growth often exacerbates this issue.
The ongoing expansion of cities is expected to increase the demand for freshwater. When aquifers are drained faster than they can be replenished, the ground compresses and sinks.
Shirzaei remarked that the combined effects of shifting weather patterns and urban expansion could accelerate subsidence rates, turning previously stable areas into ones more prone to flooding and infrastructure failures.
The study highlights the critical need to incorporate land subsidence monitoring into urban planning to mitigate infrastructure risks. Recommendations include improved groundwater management, infrastructure resilience planning, and establishing long-term monitoring systems for early detection and response.
