Land-Surface Subsidence Resulting from Ground-Water Withdrawals in the Houston-Galveston Region, Texas, Through 1987

Date

1990

Authors

Gabrysch RK
Coplin LS

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Abstract

The groundwater system in the Houston-Galveston region, Texas is composed of layers of sand and compressible clay. The system has been divided into two major aquifers, the Chicot and Evangeline, and the underlying Burkeville confining unit. The Chicot aquifer overlies the Evangeline aquifer, and contains the most permeable sand layers and also the more compressible clay layers. Large-scale groundwater withdrawals for public supply and rice irrigation began in the late 1800s and withdrawals for industrial use began after the opening of the Houston Ship Channel in 1915. In 1954, the rate of groundwater pumpage in the entire region was 388 mgd (million gal/day). Groundwater pumpage increased with increased need to 507 mgd in 1969. Pumpage during 1970-82 was relatively constant at about 500 mgd but decreased to 416 mgd by 1987. The rates of withdrawal in individual areas of the region changed significantly with the shifting of groundwater pumpage to the western part of the region, following importation of surface water to the eastern part from Lake Livingston on the Trinity River outside of the region. Water levels in wells declined throughout the region prior to 1977 as a result of groundwater withdrawals. After 1976, when groundwater pumpage in the eastern part of the region was curtailed, water levels in wells began to rise. More than 140 ft of rise in water levels was measured in some wells in both the Chicot and Evangeline aquifers by 1987. Meanwhile, water levels continued to decline in wells in the western part of the region. In the northwestern part of the region, the water level in a well in the Chicot aquifer declined as much as 60 ft; in the southwestern part of the region, the water levels in the Evangeline aquifer declined as much as 160 ft. The declines in artesian pressure (declines in water levels) have resulted in land surface subsidence of > 1 ft in an area of about 3640 sq mi. The maximum subsidence has been about 10 ft in the Pasadena Area between 1906 and 1987. However, in the Pasadena Area, the rate of subsidence of a benchmark has decreased from 0.3 ft/yr during 1973-78 to about 0.03 ft/yr during 1978-87. The maximum rate of subsidence in the western part of the region increased from about 0.2 ft/yr from 19773-78 to about 0.22 ft/yr from 1978-87. (Lantz-PTT) 35 098020000

Description

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Keywords

*Environmental effects, *Galveston, *Groundwater mining, *Groundwater withdrawal, *Houston, *Land subsidence, *Texas, Aquifer systems, Aquifers, Chicot Aquifer, Evangeline Aquifer, Groundwater, Groundwater budget, Groundwater level, Houston, Houston Ship Channel, Pumpage, Subsidence, Surface water, SW 0840 Groundwater, SW 4070 Ecological impact of water development, Texas, TRINITY RIVER, WATER, water level, Water levels, Wells, Withdrawal

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