Subsurface physical barriers have been recognized as effective in mitigating seawater intrusion in coastal aquifers, although mainly 2D (cross‐sectional) barrier effects have been considered. In this study, impermeable barriers with finite shore‐parallel lengths are investigated through 3D numerical simulation, thereby extending previous analyses. Two scenarios are considered: (a) barrier‐only and (b) barrier‐well systems; and three available barrier types are analyzed and compared: (1) subsurface dam, (2) cutoff wall, and (3) fully penetrating barrier. Barrier location, length, and height are investigated, and barrier effectiveness is evaluated from seawater volumes, seawater wedge toe positions, and maximum safe pumping rates. In the barrier‐only system, a better performance in preventing seawater intrusion was achieved by cutoff walls rather than subsurface dams. Finite‐length subsurface dams may slightly enhance seawater extent along parts of the coastline that are beyond the dam's length. Cutoff walls performed best when located at relatively small distances from the coast in the barrier‐only system, whereas with a well at 450 m from the shoreline, the subsurface dam located at a critical distance from the sea (i.e., 300 m in the current study) performed optimally (from the tested cases) and was superior to cutoff walls in terms of the maximum safe pumping rate. A fully penetrating barrier outperformed cutoff walls and subsurface dams, as expected. Our investigation indicates that subsurface barrier design should consider the effect of the shore‐parallel length, because barrier benefits may otherwise be significantly overestimated.

中文翻译：

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使用有限长度，不可渗透的地下屏障防止海水入侵并增强安全提取：3D分析

尽管主要考虑了二维（横断面）屏障效应，但人们认识到地下物理屏障可以有效缓解沿海含水层中的海水入侵。在这项研究中，通过3D数值模拟研究了具有有限岸平行长度的防渗屏障，从而扩展了先前的分析范围。考虑了两种情况：（a）仅势垒和（b）势垒井系统；分析和比较了三种可用的屏障类型：（1）地下大坝；（2）防渗墙；（3）完全穿透的屏障。对障碍物的位置，长度和高度进行了调查，并根据海水量，海水楔形趾的位置和最大安全抽水率评估了障碍物的有效性。在仅限障碍的系统中，防渗墙而不是地下大坝在防止海水入侵方面具有更好的性能。有限长度的地下水坝可能会稍微增加沿水坝长度以外的海岸线部分的海水范围。在仅设屏障的系统中，防渗墙在距海岸相对较小的距离处表现最佳，而距海岸线450 m处的一口井，地下大坝位于距海临界距离处（即当前的300 m）。研究）（在测试案例中）表现最佳，并且在最大安全抽水率方面优于隔墙。如预期的那样，完全穿透的屏障的性能优于防渗墙和地下大坝。我们的调查表明，地下屏障的设计应考虑岸线平行长度的影响，