Land Subsidence Due to Creep of the Gulf Coast Aquifer System in the Houston-Galveston Region
Land Subsidence Due to Creep of the Gulf Coast Aquifer System in the Houston-Galveston Region
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DOI：
10.2113/eeg-d-21-00076
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Yi Liu;Jiang Li
中科院分区：
文献类型：
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作者：
Yi Liu;Jiang Li
对休斯敦-加尔维斯顿地区 (TX) 的第四系和第三系墨西哥湾沿岸含水层系统沉积物的压实测量显示，当含水层系统中的地下水位在大约 2000 年之后稳定时，由于地史覆盖压力，空间可变压缩为 0.08 至 8.49 毫米/年。开发了一个含水层系统蠕变方程来评估这种可变压缩，并具有基于泰勒的厚度加权平均蠕变系数(1942)二次固结理论。地史学中，在经过长期蠕变期（如1000年以上）后，在短期观测期（如十年）内，含水层系统蠕变的时间变化可以忽略不计。墨西哥湾沿岸含水层系统的蠕变系数在 8.74 × 10−5 至 3.94 × 10−3 （无量纲）范围内，平均值为 1.38 × 10−3。此外，对于墨西哥湾沿岸含水层系统中粉质粘土或以粘土为主的弱透水层，蠕变系数值在 2.21 × 10−4 至 3.94 × 10−3 范围内变化，这与 Mesri (1973) 对大多数土壤发现的值一致，蠕变系数在 1 × 10−4 至 5 × 10−3 范围内变化。在休斯敦-加尔维斯顿地区的 13 个钻孔引伸计位置，墨西哥湾沿岸含水层系统二次固结造成的地面沉降预计在 20 世纪为 0.04 至 4.33 m，在 21 世纪预计为 0.01 至 0.64 m。除了构造沉降和原生固结之外，相对海平面上升还应考虑显着的蠕变。
The compaction measurements of Quaternary and Tertiary Gulf Coast aquifer system sediments in the Houston-Galveston region (TX) show spatially variable compression of 0.08 to 8.49 mm/yr because of geohistorical overburden pressure when groundwater levels in the aquifer system were stable after about the year 2000. An aquifer-system creep equation is developed for evaluating this variable compression, with a thickness-weighted average creep coefficient based on Taylor's (1942) secondary consolidation theory. The temporal variation of aquifer system creep can be neglected in a short-term observation period (such as a decade) after a long-term creep period (such as over 1,000 years) in geohistory. The creep coefficient of the Gulf Coast aquifer system is found to be in a range of 8.74 × 10−5 to 3.94 × 10−3 (dimensionless), with an average of 1.38 × 10−3. Moreover, for silty clay or clay-dominant aquitards in the Gulf Coast aquifer system the creep coefficient value varies in the range of 2.21 × 10−4 to 3.94 × 10−3, which is consistent with values found by Mesri (1973) for most soils, which vary in the range of creep coefficient, 1 × 10−4 to 5 × 10−3. Land subsidence due to secondary consolidation of the Gulf Coast aquifer system is estimated to be 0.04 to 4.33 m in the 20th century and is projected to be 0.01 to 0.64 m in the 21st century at the 13 borehole extensometer locations in the Houston-Galveston region. The significant creep should be considered in the relative sea level rise, in addition to tectonic subsidence and primary consolidation.