The U.S. Geological Survey (USGS), in cooperation with the Harris‐Galveston Subsidence District, City of Houston, and the Fort Bend Subsidence District, produced a dataset through 2023 of compaction values in the Chicot and Evangeline aquifers in the greater Houston area, Texas.
This dataset contains compaction values associated with subsurface sediments (mostly in the fine-grained silt and clay layers because little compaction occurs in sand layers) in the Chicot and Evangeline aquifers that were recorded continuously using analog technology. There are 14 extensometers at 12 locations (a pair of extensometers are installed at different depths at 2 of the 12 locations). Of the 14 extensometers, 13 were activated between 1973 and 1980 in either Harris or Galveston Counties, whereas the 14th extensometer was activated in Fort Bend County in 2017. Data from one of the 14 extensometers (one of the two extensometers at the Baytown site) are not being published this year because of an equipment malfunction at this site. The cumulative compaction data for each extensometer are retrieved about 12 times per year during site visits. Cumulative compaction data collected at each extensometer are provided, starting with the data from the year the extensometer was installed through 2023. The amount of compaction measured between site visits is determined by subtracting the cumulative compaction value associated with the earlier of the two site visits of interest from the cumulative compaction value associated with the latter of the two site visits of interest.
First release: May 2019
Revised: June 2020 (ver. 2.0)
Revised: March 2022 (ver. 3.0)
Revised: November 2022 (ver. 4.0)
Revised: August 2023 (ver. 5.0)
Revised: September 2024 (ver. 6.0)
