Approximate altitude of water levels in wells in the Chicot and Evangeline aquifers in the Houston area, Texas, Spring 1977 and Spring 1978

Hydrogeology and simulation of ground-water flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system, Texas

“…Because of the weight of the overburden and the inelastic compaction characteristics of the clay layers, about 90 percent of the compaction is permanent (Gabrysch and Bonnet, 1975). Thus, when potentiometric surfaces rise and repressure compacted clay layers there is little, if any, rebound of the land surface (Gabrysch and Bonnet, 1975).…”

“…Thus, when potentiometric surfaces rise and repressure compacted clay layers there is little, if any, rebound of the land surface (Gabrysch and Bonnet, 1975). Although the compaction of one clay layer generally will not cause a noticeable decrease in the land-surface altitude, if numerous stacked clay-layer sequences (which are characteristic of the Gulf Coast aquifer system) depressure and compact, then appreciable decreases in land-surface altitude can and do occur (Gabrysch and Bonnet, 1975). More than 10 ft of land-surface subsidence has been documented in the Baytown and Houston Ship Channel area in southwestern Harris County (Harris-Galveston Coastal Subsidence District, 1998), as will be shown in the "Model Calibration" section.…”

“…In addition, graphical relations between simulated and measured heads for each aquifer for 1977 and 2000 were developed. The 1977 potentiometric surfaces were chosen for "history matching" because that was the first year of comprehensive, synoptic head measurements in the Chicot and Evangeline aquifers, at least in the Houston area (Gabrysch, 1979), following record-high withdrawals during the 1970s (fig. 33).…”

“…For the rest of the area of the system, initial inelastic clay storativities were computed by multiplying areally distributed values of clay thickness from Gabrysch (1982) and Strom and others (2003a, b) (figs. 12, 18) by values of inelastic clay specific storage from Meyer and Carr (1979, p. 13) (8.7 X 10 -5 ft -1 for Chicot aquifer and 1.5 X 10 -5 ft -1 for Evangeline aquifer).…”

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

“…In cooperation with the HGSD, the USGS has monitored water levels in wells screened in the Chicot and Evangeline aquifers and compaction of subsurface sediments in Harris and Galveston Counties since 1976. The USGS has published annual reports depicting water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region beginning with the 1977 water-level-altitude maps (Gabrysch, 1979). Subsequently, the monitoring of groundwater levels was expanded into the Fort Bend subregion (encompassing Fort Bend County and adjacent areas), and the first water-level-altitude maps for this area were created and presented in the 1991 waterlevel report (Barbie and others, 1991) and subsequently revised in 1997 (Kasmarek, 1997).…”