Recent satellite data has unveiled a troubling reality: Houston, Texas, is the fastest-sinking city in the United States. Scientists have documented that Houston is sinking fast. This crisis affects 34 million Americans in every large US metropolitan area. Groundwater extraction is a major contributor to this alarming trend, as these exploding wells illustrate. With this event, it contorted critical infrastructure and increased the likelihood for severe flooding.
Perhaps most importantly, the study indicates that Houston is particularly susceptible. A shocking 43% of its land is currently experiencing subsidence at speeds above 5 millimeters per year. 12% of the city is subject to more extreme sinking, at a rate of 10 millimeters a year. This alarming land subsidence is a source of constant worry for citizens and city planners as well.
The Scale of Subsidence Across Major Cities
This study uncovered a very disturbing deepening trend in Houston. Together with Dallas and Fort Worth, over 70% of its neighborhoods are sinking at least 0.1 inches (over 3 mm) annually. As just one example, some neighborhoods on the east side of #Houston are sinking at a jaw-dropping rate of 0.4 inches (10 mm) per year. With widespread subsidence impacting an astonishing 98% of urban land that’s a city-changing phenomenon, happening in cities like Chicago, Columbus, Detroit, Denver, New York, Indianapolis, and Charlotte.
Nationally, it is estimated that at least 65% of the area are experiencing relative sinking in 25 of the 28 cities examined. This points to a major, often overlooked burden on many cities’ built environments. Alarmingly, each city in the survey has at least 20% of its urban area impacted by this problem.
“As opposed to just saying it’s a problem, we can respond, address, mitigate, adapt,” – Leonard Ohenhen
Groundwater Extraction: The Culprit Behind Sinking
Over a staggering 80% of land subsidence in urban areas is attributable to the removal of groundwater. Even more dangerous, this process puts the structural integrity of those buildings and communities at dire risk, while intensifying flooding hazards in vulnerable communities. Of the study’s relatively short list of known effects, vertical land motion has already put more than 29,000 publicly owned buildings in climate-risky areas.
Texas is caught in a tough bind given its outsized role in the oil & gas industry. Yet these operations are known for creating dangerous land subsidence. As cities grow deeper into subsiding areas, the potential for disaster flooding grows.
“As cities continue to grow, we will see more cities expand into subsiding regions,” – Leonard Ohenhen
Implications for Urban Areas and Climate Change
Land subsidence is by no means limited to coastal regions, and it is increasingly becoming a threat nationwide. For instance, parts of San Francisco and Los Angeles are sinking into the sea, worsening the impacts of sea-level rise. As cities and towns expand and build upon previously unsettled lands, researchers caution that risks associated with subsidence will see a rise as well.
Taken together, these new findings point to an urgent need. This means cities need to embrace better strategies for protecting groundwater reserves and preventing land subsidence. Neglecting to take this action will lead to massively increased damage to infrastructure and greater risk to the population from environmental dangers.
