Greuter and two co-authors, reported in early 2021 that it is well known that land subsidence has affected the greater Houston-Galveston region for over a century [see Campbell, et al., (2018)]. Land subsidence in this region is caused by aquifer compaction due to groundwater withdrawal. Previous research has shown significant subsidence occurred from 1906 to 1978 with measured subsidence around 10 feet in the Houston Ship Channel. The Harris-Galveston Subsidence District (Subsidence District) was established in 1975 to regulate groundwater withdrawals in order to prevent subsidence in Harris and Galveston counties.
After the creation of the Subsidence District, groundwater withdrawal was first regulated in Galveston County and southeast Harris County. This regulation resulted in less than one-tenth of one foot of subsidence recorded around the Houston Ship Channel from 1977 to 1985. More recently, the Subsidence District performed a wholistic analysis on historical measured subsidence using data from published reports and the subsidence monitoring network that were used as input parameters to model subsidence in the region. This analysis produced two key results that both show how the regulation of groundwater withdrawal can effectively lessen and even eliminate subsidence.
The areas like Pasadena and the Houston Ship Channel in the greater Houston-Galveston region experienced up to ten feet of subsidence due to aquifer compaction from significant groundwater withdrawal from 1906 to 1978. The Subsidence District was established in 1975 by the Texas Legislature with the purpose of regulating groundwater withdrawal to prevent subsidence. From data collection ranging from large scale first-order surveys to GPS monitoring as
well as detailed and informed regulatory planning, the Subsidence District has continued to use innovative techniques to monitor subsidence in this region.
Land surface elevation data acquired from leveling surveys and GPS data over the past 40 years has been critical to understand the changes in subsidence rates in the greater Houston-Galveston region. The impact of the Subsidence District’s regulation of groundwater withdrawal within fully converted regulatory areas is further demonstrated as water level altitudes in the Chicot and Evangeline aquifers have increased up to 240 feet from 1977 to 2021 in the Pasadena area (Greuter and Petersen, 2021).
Galveston County and portions of southeast Harris County began the conversion to alternative water in the 1980s and culminated in the mid-1990s. As a result of this conversion, subsidence was greatly reduced in these areas. Within the past 20 years, practically no subsidence has occurred in fully converted regulatory areas. Future conversion milestones will aid in the lessening of subsidence in portions of northwest Harris County and continued regulatory planning founded in high-quality and best available science will help achieve the Subsidence District’s mission to prevent subsidence. The vertical displacement, as shown in the change in ellipsoidal height, from 2000 through 2020 was used to estimate the subsidence experienced at site P001. This value was used as input to model the estimated subsidence contours from 2000 to 2020.
Total estimated subsidence from 1978 to 2000, in feet, utilizing GIS grid subtraction of measured subsidence from 1906 to 1978 (Gabrysch, 1982) and measured subsidence from 1906 to 2000 (Gabrysch and Neighbors, 2005).
REFERENCES CITED
Campbell M. D, M. David Campbell, and Wise H. M., 2018, "Growth Faulting and Subsidence in the Houston, Texas Area: Guide to the Origins, Relationships, Hazards, Potential Impacts and Methods of Investigation: An Update. "J Geol Geosci Vol. 2: pp. 001-053. URL: http://www.i2mconsultants.com/downloads/corp/JGG-1-015.pdf, Additional Area References: https://i2mconsultants.com/downloads/ela-iet/Bibliography011204.pdf
Agudelo, G., G. Wang, Y. Lui, Y. Bao, and M. J. Turco, 2020, "GPS geodetic infrastructure for subsidence and fault monitoring in Houston, Texas, USA," Proceedings of the International Association of Hydrological Sciences, 10th International Symposium on Land Subsidence, Delft Gouda, The Netherlands, v. 382, pp. 11–18, URL: https://doi.org/10.5194/piahs-382-11-2020.
Baker, E. T., 1979, Stratigraphic and hydrogeologic framework of part of the coastal plain of Texas: Texas Department of Water Resources Report 236, Austin, 43 p. Figure 6.
Gabrysch, R. K. and R. J. Neighbors, 2000, Land-surface subsidence and its control in the Houston-Galveston region, Texas, 1906–1995. In Carbognin, L.; Gambolati, G.; and Johnson, A. I. (Editors), Proceedings of the Sixth International Symposium on Land Subsidence (24–29 September),
Vol. 2: CNR, Ravenna, Italy, pp. 81–92.
Gabrysch, R. K., "Ground-water withdrawals and land-surface subsidence in the Houston-Galveston region, Texas, 1906-80,"
U.S. Geological Survey Open-File Report 82-571, URL: https://pubs.er.usgs.gov/publication/ofr82571 and https://doi.org/10.3133/ofr82571
Greuter, A., and C. Petersen, 2020, "Determination of Groundwater Withdrawal and Subsidence in Harris and Galveston Counties – 2020
URL: https://hgsubsidence.org/wp-content/uploads/2021/05/2020-HGSD-AGR_Full-Report-1.pdf
Wang, K., Wang, G., Cornelison, B. et al., 2021, "Land subsidence and aquifer compaction in Montgomery County, Texas, U.S.: 2000–2020,". Geoenviron Disasters 8, Vol. 28, URL: https://doi.org/10.1186/s40677-021-00199-7
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