A recent study published in Nature Cities reveals a growing threat to urban infrastructure across the United States: land subsidence. This slow and gradual sinking of the Earth’s surface is impacting major cities, with San Antonio, Texas, facing particularly high risks.

San Antonio’s Alarming Situation

San Antonio has a concerning number of buildings at “high” or “very high” risk of damage due to land subsidence. The study identifies 10,269 buildings in the Alamo City facing potential damage,significantly more than any other U.S. city analyzed. This translates to approximately one out of every 45 buildings in San Antonio being at risk, primarily due to differential land motion.

The Silent Threat

the study emphasizes the insidious nature of land subsidence, stating:

The latent nature of this risk means that infrastructure can be silently compromised over time, with damage only becoming evidence when it is indeed severe or perhaps catastrophic.

This highlights the importance of proactive monitoring and mitigation efforts to prevent potentially devastating consequences.

Beyond Coastal Areas

The research challenges the conventional understanding of land subsidence as solely a coastal issue. It demonstrates that inland urban areas are also vulnerable,facing increased flood risks,structural damage,and transportation disruptions.

Groundwater Extraction: A Major Culprit

The study focused on the 28 most populous U.S. cities and found that in all of them, at least 20% of the area is sinking “mainly due to groundwater extraction.” Excessive removal of groundwater weakens the soil structure, leading to land subsidence.

Widespread Impact

The consequences of even modest rates of urban subsidence can be significant. Nature Cities found that:

Even modest rates of urban subsidence can profoundly impact the structural integrity of buildings, roads, bridges and dams.

The study also notes that sinking exacerbates flooding risk, compounding the challenges faced by urban areas.

Texas Cities at Risk

Several Texas cities are particularly affected by land subsidence. The study highlights the following:

• 75.6% of Fort Worth is sinking at a rate of between 3 and 5 millimeters a year.
• 83.9% of Dallas is sinking at the same rate.
• 30.1% of Houston is sinking at a rate of between 5 and 10 millimeters a year.

Houston: The Fastest-Sinking City

Houston faces the most severe subsidence among the cities analyzed. Approximately 11.6% of the city is sinking at a rate of more than 10 millimeters a year, making it the fastest-sinking city in the study. Of the five cities with at least 10% of surface area sinking at rates faster than 3 millimeters a year, three – houston, Dallas, and fort Worth – are located in Texas.

San Antonio’s Residents Affected

In San Antonio, a significant portion of the population is living in areas affected by land subsidence. approximately 1.05 million of the city’s roughly 1.5 million residents live in areas where the land is sinking. Generally, the city is sinking at a rate of 1.1 millimeters a year.

Call for Action

The study emphasizes the urgent need for infrastructural adaptation and enduring groundwater management. Researchers wrote that the findings emphasize:

The immediate needs for infrastructural adaptation to promote sustainable urban advancement in the face escalating environmental pressures to the long-term imperatives of groundwater management.