Subsidence, the slow-on-the-go caving of a land area, isn’t a new or even unnatural phenomenon in the Houston area. It’s how humans accelerate this sinking that’s not all that normal or awesome.
In the 1980s, Brownwood, the Houston Ship Channel-area subdivision that once housed Humble Oil (now Exxon) bigwigs, basically caved in on itself. That’s because oil workers and municipal companies had pumped out groundwater, which was used for oil and gas production and for residential purposes, at an insanely fast rate for decades.
The Chicot and Evangeline aquifers along the Texas Gulf Coast weren’t able to naturally replenish the groundwater supply. Loose groundwater regulations at the time certainly didn’t help, and the eventual switch to surface water was too late because the damage had been done — according to United States Geological Survey data, approximately 4,700 square miles of land in and near Baytown and Pasadena sank by at least six feet between the years 1943 and 1973.
Eventually, Brownwood went kaput. Today, the area houses the Baytown Nature Center, where joggers, baby-stroller-pushing families and resident fowl play on top of the remains of two-story homes and swimming pools.
History is repeating-ish itself all over Houston, including in an area northeast of Addicks Reservoir, one of two dams in far west Houston that the United States Corps of Engineers, in 2009, labeled with an ominous “extremely high risk of catastrophic failure” warning.
According to a December 2013 U.S. Geological Survey map that was recently published in David Todd’s and Jonathan Ogren’s book The Texas Landscape Project: Nature and People (Texas A&M University Press), an area in far northwest Harris County sank by seven feet between 1891 and 2009.
“Imagine a really flat tabletop and you’ve got a dent in the middle of the table that’s seven feet deep. If you pour water in that hole, it’s not going to drain,” says Todd, an Austin-based environmental attorney and executive director of the Conservation History Association of Texas.
“Also, big residential subdivisions have been built nearby…and it has been expensive and difficult to get water to the west side of town so they must rely on groundwater and wells,” says Todd, who, along with Ogren, a University of Texas at Austin lecturer, recently published the visual-heavy The Texas Landscape Project, a book that acts as an environmental-history atlas for the entire state.
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The subsidence problem is exacerbated because Houston's mega-metropolis is built on clay, which doesn’t contain the stability of bedrock. As more groundwater is removed from beneath the surface, the clay cracks and shrinks.
“And then the ground drops,” says Todd, something that communities like Jersey Village have known about for a minute.
“The clay shrinks when any sulfur, fluid or gas is pulled out,” says Todd. “This subsidence has altered upland drainage patterns, exposed coastal areas to storm surge and, in those ways, raised flood risks for the Houston region.”
In short, humans = yet another fail.