What is it about?
The Houston area in Texas, United States, has been experiencing land subsidence for a century from the 1920s to 2010s. A substantial portion of the Houston area had finished a consolidation cycle following the long-term hydraulic head decline and recovery. A new ‘‘maximum effective stress’’ (preconsolidation stress) was preserved in the memory of the aquitards. For an aquifer system comprising aquifers and aquitards, the preconsolidation stress is corresponding to the lowest hydraulic head in the aquitards, not in the aquifers. Preconsolidation head is generally regarded as a groundwater-level threshold below which inelastic compaction begins. The preconsolidation head finalized after the long-term hydraulic head decline and recovery is called new preconsolidation head. This study has developed an empirical equation for projecting the new preconsolidation head. According to this study, the newpreconsolidation heads in the primary aquifers (lower Chicot and Evangeline) are local specific: varying from about 30m below land surface (−30 m) in the south to −50m in the north of the Harris-Galveston Subsidence District (HGSD) Regulatory Area 1, from −60m in the east to −80m in the west of Area 2, and from −70m in the south to −100m in the center of Area 3. In Areas 1 and 2, the current hydraulic heads are about 10 m to 20m higher than the local new preconsolidation heads; thus, remarkable land subsidence (>1 cm/year) would not be reinitiated unless the hydraulic heads are to fall below the local new preconsolidation head.
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Why is it important?
An empirical equation has been developed for projecting the new preconsolidation heads in the greater Houston area, Texas, United States, which can be used as a tool to address future groundwater-availability and subsidence issues.
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This page is a summary of: New Preconsolidation Heads Following the
Decline and Recovery in Houston, Texas, Ground Water, November 2022, Wiley,
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Figure S1 The histories of groundwater levels and aquifer compaction at Lake Houston extensometer site. Figure S2. The histories of groundwater levels and aquifer compaction at Northeast extensometer site. Figure S3. The histories of groundwater levels and aquifer compaction at East End extensometer site. Figure S4. The histories of groundwater levels and aquifer compaction at Baytown shallow and deep extensometer sites. Figure S5. The histories of groundwater levels and aquifer compaction at Johnson Space Center and Clear Lake (shallow and deep) extensometer sites. Figure S6. The histories of groundwater levels and aquifer compaction at Seabrook extensometer site. Figure S7. The histories of groundwater levels and aquifer compaction at Texas City extensometer site. Table S1. Detailed information of 320 V-shape groundwater-level records used for projecting the new preconsolidation heads in the Houston area (Figure 11).
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