In the simplest of terms, land subsidence is the gradual sinking of the Earth’s surface due to subsurface movement. In the greater Houston area, groundwater withdrawals have caused subsidence, or land sinking.
Although the process is slower than that of other natural hazards, subsidence has serious consequences. Once subsidence has occurred in our area, it is irreversible. Given our region’s proximity to the coast, any loss of land surface elevation poses significant threats from weather-related events like storm surges and flooding.
To prevent further subsidence, the Harris-Galveston Subsidence District works diligently to reduce reliance on groundwater through groundwater regulation and water conservation.
Illustration of subsidence in a Gulf Coast aquifer as a result of groundwater withdrawals producing a decrease in the potentiometric surface (the groundwater level). Source: Kasmarek, M.C., Ramage, J.K., and Johnson, M.R., 2016, Water-level altitudes 2016 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973–2015 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas: U.S. Geological Survey Scientific Investigations Map 3365, pamphlet, 16 sheets, scale 1:100,000, http://dx.doi.org/10.3133/sim3365.