Major cities across the nation are sinking, affecting more than 34 million people and putting thousands of buildings at risk, according to newly released satellite data. In Texas, metropolitan areas such as Houston, San Antonio, Austin and Dallas are among the most impacted.
An online journal used satellite data covering the past six years to identify the 28 most populous across the nation that are sinking the fastest. Out of those cities, Houston leads the pack, with more than 40% of its land area sinking more than 5 millimeters (mm) per year and 12% sinking up to 10 mm. Houston’s rate of sinking doubles the national average, with at least 20% of the urban areas in these cities sinking.
Traditionally associated with coastal communities, the data indicates that land subsidence is affecting more and more landlocked urban areas. While there are many causes for widespread subsidence, the most common is groundwater extraction.
While Houston is sinking the fastest, Fort Worth, Dallas, Austin and San Antonio are not far behind. As urban subsidence worsens due to ongoing development, climate change and other types of human interference, urban infrastructure will be put at increasing risk of disaster. Subsidence exacerbates flood hazards, making cities more vulnerable to flooding and water will more easily collect in specific regions with limited conveyance options.
San Antonio stands out as one of the highest-risk cities for damage from land subsidence. The city has by far the largest number of buildings assessed as vulnerable to land subsisdence, including 8,754 that are high-risk and 1,515 that are very-high-risk. More than 80% of the city’s infrastructure is expected to be impacted, including buildings, bridges and roads. Houston, Austin and Fort Worth, in comparison, have less than half the same number of vulnerable structures.
Subsidence is a slow process, and cities still have the opportunity to take proactive action and address these issues before they become unmanageable. Mitigation and adaptation efforts typically revolve around enhancing infrastructure resilience, retrofitting essential infrastructure and relocating and limiting buildings in high-risk areas.
Photo Courtesy E’s & D’s Adventures in Life via Wikimedia Commons
