Groundwater dynamics in the coastal unconfined aquifer is one of the most important physical factors in the coastal zone since it greatly influences the nearshore hydrodynamics and beach morphodynamics, as well as interactions between oceanic and inland water systems. A solid understanding of the groundwater behavior in the coastal area is necessary for maintaining efficient coastal water management and supporting sustainable social-ecological development. Coastal unconfined aquifers are complicated while active systems in response to multiple oceanic forces such as tides and waves in various spatiotemporal scales, which have been evaluated and investigated over the last few decades. The present paper provides a comprehensive review of current understandings and advances in groundwater dynamics in coastal unconfined aquifers with respect to water table fluctuations and groundwater flow patterns, with a particular focus on wave-induced groundwater hydrodynamics. Existing analytical approaches for predicting the groundwater response to oceanic forces are summarized and evaluated to reveal their pros and cons. Although great advances have been achieved, some knowledge gaps still remain. While the influences of tide forces on coastal groundwater dynamics are generally well understood and tide-induced groundwater dynamics could be appropriately reproduced by various existing analytical or numerical models, groundwater dynamics in response to wave forces are relatively poorly understood. Accordingly, research needs with respect to groundwater dynamics are discussed and identified in this review. Many studies evaluate the wave-induced groundwater hydrodynamics based on experimental or field observations, while sophisticated theoretical approaches are still lacking to quantify the influence of various complex physical factors during wave swash events, such as capillary truncations, seepage face dynamics, and wetting front evolutions. Such knowledge gaps need to be filled in order to further advance our understanding of the coastal groundwater dynamics and, furthermore, to conduct effective and sustainable coastal water management and protection.

中文翻译：

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以波浪效应为重点的沿海地下水动力学


沿海无承压含水层地下水动力学是沿海地区最重要的物理因素之一，它极大地影响着近岸水动力学和海滩形态动力学以及海洋与内陆水系统之间的相互作用。对沿海地区地下水行为的深入了解对于维持有效的沿海水资源管理和支持可持续的社会生态发展是必要的。沿海无承压含水层是复杂而活跃的系统，可响应各种时空尺度的潮汐和波浪等多种海洋力，在过去的几十年中已对其进行了评估和研究。本文全面回顾了沿海无承压含水层地下水动力学在地下水位波动和地下水流模式方面的最新认识和进展，特别关注波浪引起的地下水流体动力学。对预测地下水对海洋力的响应的现有分析方法进行了总结和评估，以揭示其优缺点。尽管已经取得了巨大进步，但仍然存在一些知识差距。虽然潮汐力对沿海地下水动态的影响通常被很好地理解，并且潮汐引起的地下水动态可以通过各种现有的分析或数值模型适当地再现，但对波浪力响应的地下水动态知之甚少。因此，本综述讨论并确定了地下水动力学方面的研究需求。 许多研究基于实验或现场观测来评估波浪引起的地下水动力学，但仍然缺乏复杂的理论方法来量化波浪冲刷事件期间各种复杂物理因素的影响，例如毛细管截断、渗流面动力学和润湿锋演化。需要填补这些知识空白，以进一步增进我们对沿海地下水动态的了解，并进一步进行有效和可持续的沿海水资源管理和保护。