Tidally induced groundwater circulation in an unconfined coastal aquifer modeled with a Hele-Shaw cell
Tidally induced groundwater circulation in an unconfined coastal aquifer modeled with a Hele-Shaw cell
复制标题
使用 Hele-Shaw 单元模拟的无承压沿海含水层中潮汐引起的地下水循环
作者：
Aaron J. Mango;M. Schmeeckle;D. Furbish
我们使用缩放的 Hele-Shaw 单元来模拟无承压含水层中潮汐引起的近岸地下水运动。沙滩的低坡角导致潮汐循环期间水-沉积物界面上的流体交换呈现强烈的不对称模式。这种不对称性导致地下水循环的时间平均集中在低潮位以下；运动的水平分量和垂直分量具有相同的阶数。水平向海流在界面下方延伸了相当大的深度，与高于平均海平面的时间平均地下水位一致，提供了驱动更深的质量输出所需的水力梯度，其等于渗透的时间平均流入量。这种潮汐强迫流动行为可能导致观测到的海底渗流率波动。此外，环流主要涉及海水在涨潮期间渗透的地下循环。因此，潮汐带附近海底渗漏的测量可能涉及循环海水和淡水流。
We use a scaled Hele-Shaw cell to mimic tidally induced nearshore groundwater motion in an unconfined aquifer. The low slope angle of sandy beaches contributes to a strongly asymmetric pattern of fluid exchange across the water-sediment interface during tidal cycles. This asymmetry leads to a time-averaged groundwater circulation centered beneath the low-tide level; horizontal and vertical components of motion are of the same order. Horizontal seaward flow extends a significant depth beneath the interface, consonant with a time-averaged water table that is elevated above mean sea level, providing the hydraulic gradient necessary to drive this deeper export of mass equal to the time-averaged inflow by infiltration. This tidally forced flow behavior likely contributes to observed fluctuations in submarine seepage rates. Moreover, the circulation largely involves a subsurface cycling of seawater that infiltrates during the rising tide. Measurements of submarine seepage near the tidal zone therefore likely involve this cycled seawater as well as freshwater flows.