Semi-analytical solution of land-derived solute transport under tidal fluctuation in a confined aquifer
Semi-analytical solution of land-derived solute transport under tidal fluctuation in a confined aquifer
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DOI：
10.1016/j.jhydrol.2017.09.033
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发表时间：
2017-11
影响因子：
6.4
通讯作者：
H. Suk
中科院分区：
文献类型：
--
作者：
H. Suk
利用广义积分变换技术(GITT)推导了潮汐作用下滨海承压含水层中陆源溶质运移的一维半解析解。为了研究受潮汐影响的含水层中陆源污染物的羽流迁移，考虑了由地下水水头响应的解析解获得的达西速度和弥散系数的空间和时间变化表达式，这些表达式受潮汐波动的正弦边界条件的影响。新的半解析解与数值解以及用预估-校正法得到的峰位轨迹进行了验证。通过对潮汐幅值、水力传导性和蓄水系数的敏感性分析，了解了羽流形状、空间矩和宏观弥散系数对羽流行为的影响，从而更好地了解了羽流的输运机制。随着潮汐幅值、导水率和蓄水系数的增大，峰位移动速度加快，峰位浓度降低。此外，潮汐振幅、水力传导性和蓄水系数的增加导致方差和宏观弥散系数的增加。结果表明，当储存系数最大时，以及羽流前缘和尾缘向陆地平流速度差最大时，都会出现负的宏观弥散。这一新开发的半解析解为验证数值模型和了解受潮汐影响的含水层内羽流向海洋或河口迁移的物理机制提供了有用的数学工具。
A one-dimensional semi-analytical solution of land-derived solute transport, subject to tidal fluctuation in a coastal confined aquifer, was derived using the generalized integral-transform technique (GITT). To investigate the plume migration of land-derived contaminants within a tidally influenced aquifer, both spatially and temporally varying expressions of the Darcy velocity and dispersion coefficients obtained from the analytical solution of the groundwater head response, which were subject to sinusoidal boundary conditions due to tidal fluctuation, were considered. This new semi-analytical solution was verified against a numerical solution, as well as the peak location trajectory obtained using the Predictor-Corrector method. Sensitivity analyses of tidal amplitude, hydraulic conductivity, and storage coefficient using the proposed solution were performed to understand plume behavior with regard to plume shape, plume spatial moments, and macrodispersion coefficients to gain a better understanding of the transport mechanisms. As the tidal amplitude, hydraulic conductivity, and storage coefficient were increased, the peaks were travelled faster, and peak concentrations were decreased. In addition, an increase in tidal amplitude, hydraulic conductivity, and storage coefficient caused an increase in variance as well as the macrodispersion coefficient. It was observed that negative macrodispersion appeared when the storage coefficient was largest, as well as when the difference between landward-directed advective velocity at the leading and trailing edges of the plume was greatest. This newly developed semi-analytical solution provides a useful mathematical tool for validating numerical models and understanding the physical mechanism of the migration of plume discharge to the sea or estuaries within a tidally influenced aquifer.