College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; College of Marine Geosciences, Ocean University of China, Qingdao 266100, China.
College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecological Education, Ocean University of China, Qingdao 266100, China.
Sci Total Environ. 2023 Jun 15;877:162857. doi: 10.1016/j.scitotenv.2023.162857. Epub 2023 Mar 15.
For the coastal aquifers, recent research have shown that the tidal has a significant effect on saltwater intrusion in the near-shore aquifer. However, it is currently unclear how the tidal river contributes to the groundwater flow and salinity distribution in the upstream aquifer of the estuary. This study examined the effects of a tidal river on the dynamic characteristics of groundwater flow and salt transport in a tidal river-coastal aquifer system using field monitoring data and numerical simulations. It was found that changes in tidal-river level led to the reversal of groundwater flow. For a tidal cycle, the maximum area of seawater intrusion is about 41.16 km at the end of the high tide stage. Then the area gradually decreased to 39.02 km at the end of the low tide stage. More than 2 km area variation can be observed in a tidal cycle. Compared to the low tide stage, the area of SWI increased by 5 % at high tide stage. The SWI region was also spreading landward from the tidal river. In addition, we quantified the water exchange and salt flux between the tidal river and aquifer. When the tidal fell below the level of the riverbed, the water exchange rate was stabilized at about -1.6 m/h. The negative value indicated that the river was recharged by the groundwater. With the increasing of tidal water level, the water exchange rate gradually changes from negative to positive and reached the maximum value of 3.2 m/h at the beginning of the falling tide stage. The presence of a physical river dam can amplify the difference in water level between high and low tides, thereby enhancing the influence of a tidal river on water exchange and salt flux. The findings lay the foundation for gaining a comprehensive understanding of the tidal river on groundwater flow and salt transport in upstream aquifers.
对于沿海含水层，最近的研究表明潮汐对近岸含水层的海水入侵有显著影响。然而，目前尚不清楚潮汐河如何影响河口上游含水层的地下水流动和盐度分布。本研究利用现场监测数据和数值模拟，研究了潮汐河对潮汐河-沿海含水层系统地下水流动和盐运移动态特征的影响。结果表明，潮汐河水位的变化导致地下水流动方向发生反转。在一个潮汐周期内，高潮位结束时海水入侵的最大面积约为 41.16 公里。然后，面积逐渐减少到低潮位结束时的 39.02 公里。在一个潮汐周期内可以观察到超过 2 公里的面积变化。与低潮位相比，高潮位时 SWI 面积增加了 5%。SWI 区域也从潮汐河向陆地扩展。此外，我们量化了潮汐河与含水层之间的水交换和盐通量。当潮汐低于河床水平时，水交换率稳定在约-1.6 米/小时。负值表示河水被地下水补给。随着潮汐水位的升高，水交换率逐渐由负转正，并在落潮开始时达到 3.2 米/小时的最大值。物理河流堰的存在可以放大高低潮之间的水位差异，从而增强潮汐河对水交换和盐通量的影响。研究结果为全面了解潮汐河对上游含水层地下水流动和盐运移的影响奠定了基础。
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