Collaborative Res: Assessing Aquifer Properties from Stress and Strain Distributions in Leaky-Confined Aquifers using Insar, GPS and Three-Dimensional Deformation and Flow Modeling

[0106474]含水层测试通常包括在抽水井附近收集时间下降数据，以便绘制估算含水层或含水层系统的储存系数和透过率的图。GPS技术和INSAR（干涉合成孔径雷达）卫星图像的最新进展，使陆地表面位移的详细和精确计算成为可能。在主动抽水试验期间，固定式GPS监测与同一区域的INSAR干涉图相结合，将允许与水文数据一起收集时间压实（和时间水平应变）数据，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，在以围水单元为主要可压缩单元的渗漏含水层系统中，时间压实数据可以提供必要的信息，以准确计算围水单元的比储水量和垂向水力导率，这些参数通常难以评估。采用半对数（封闭）和半对数（泄漏）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以及围封单元的储水量和垂向水力导率。GPS和INSAR调查还将提供陆地表面水平变形的详细信息，并可以证实三维变形和流动假设模型的结果，该模型表明，超过50%的抽水从承压含水层中与水平应变相关的储存中释放出来。这些结果可能对测量沉降、通过围封装置实际预期的泄漏量以及对长期含水层测试的解释产生重大影响。此外，三维应变存在时，通过围封单元的应变配置会有很大不同，随着时间的推移，这将影响通过围封单元的潜在压实和泄漏。水从水平应变的潜在贡献可能需要我们重新考虑目前的储存系数的定义，这种应变被忽视。

0106474BurbeyAquifer 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.