Collaborative Research: Aquifer Deformation Using GPS

合作研究：利用 GPS 测量含水层变形

• 批准号: 0135251
• 负责人: Geoffrey Blewitt
• 金额: $ 9.71万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0135251&HistoricalAwards=false
• 关键词: Collaborative; Research; Aquifer; Deformation; Using

0135251BlewittAquifer tests typically involve collecting time-drawdown data in the vicinity of a pumping well for the purpose of producing plots for estimating the storage coefficient and transmissivity of the aquifer or aquifer system. Recent advances in GPS technology and INSAR (interferometric synthetic aperture radar) satellite imagery, allow for detailed and precise calculation of land surface displacements. Stationary GPS monitoring during an active pumping test in conjunction with INSAR interferograms for the same region will allow for time-compaction (and time-horizontal strain) data to be collected in conjunction with the hydrograph data providing a far more diagnostic test for estimating storage coefiricient of confined aquifers. Furthermore, in leaky aquifer systems in which the confining unit is the primary compressible unit, the time-compaction data can provide the necessary information to accurately calculate the speciric storage and vertical hydraulic conductivity of the confining unit, parameters that are typically difficult to evaluate. A new analytical solution has been developed to derive the storage coefficient from time-subsidence data and numerical simulation results applied to this semi-log (conrined) and semi-log (leaky) methodology indicates that extremely accurate estimates for storage of the aquifer and storage and vertical hydraulic conductivity of the confining unit can be made.GPS and INSAR surveys will also provide detailed information on horizontal deformation occurring at the land surface and can corroborate results from hypothetical modeling of three-dimensional deformation and flow, which indicate that more than 50 percent of pumped water is released from storage associated with horizontal strain in confined aquifers. These results may have tremendous implications with regard to measuring subsidence, the quantity of leakage that can actually be expected through confining units, and the interpretation of long-term aquifer tests. Furthermore, the strain configuration through the confining unit will be much different in the presence of three-dimensional strain, which will affect the potential compaction and leakage through the confining unit over time. The potential contribution of water from horizontal strain may require us to rethink the current definition of storage coefficient where such strains have been neglected.

Blewitt含水层测试通常涉及收集抽水井附近的时间下降数据，以便制作用于估计含水层或含水层系统的储存系数和导水率的地块。全球定位系统技术和InSAR(干涉合成孔径雷达)卫星图像的最新进展使人们能够详细和精确地计算陆地表面的位移。在主动抽水试验期间的固定GPS监测与同一区域的InSAR干涉图相结合，将使时间压实(和时间-水平应变)数据能够与水位线数据一起收集，从而为估计承压含水层的储存系数提供更具诊断性的测试。此外，在以封闭单元为主要可压缩单元的漏水含水层系统中，时间压实数据可以提供必要的信息，以准确计算封闭单元的特定储水量和垂直水力传导率，而这些参数通常很难评估。应用于这种半对数(约束)和半对数(渗漏)方法的数值模拟结果表明，可以非常准确地估计含水层的储水量、储水量和封闭单元的垂直水力传导性。GPS和InSAR测量还将提供关于地表发生的水平变形的详细信息，并可以证实三维变形和流动假想模拟的结果，这表明超过50%的抽水是从与承压含水层水平应变相关的储水量中释放出来的。这些结果可能会对测量沉降量、通过封闭单元实际预计的渗漏量以及解释长期含水层测试产生巨大影响。此外，在三维应变存在的情况下，通过限制单元的应变配置将有很大不同，这将随着时间的推移影响通过限制单元的潜在压实和泄漏。水平应变对水的潜在贡献可能要求我们重新考虑目前对储存系数的定义，其中忽略了这些应变。