The behavior and predictability of rip currents (strong, wave-driven offshore-directed surfzone currents) have been studied for decades. However, few studies have examined the effects of rip channel morphology on the rip generation or have compared morphodynamic models with observations. Here, simulations conducted with the numerical morphodynamic model MIKE21 reproduce observed trends in flows and bathymetric evolution for two channels dredged across a nearshore sandbar and terrace on an ocean beach near Duck, NC, USA. Channel dimensions, wave conditions, and flows differed between the two cases. In one case, a strong rip current was driven by moderate height, near-normally incident waves over an approximately 1-m deep channel with relatively little bathymetric evolution. In the other case, no rip was generated by the large, near-normally incident waves over the shallower (∼0.5 m) channel, and the channel migrated in the direction of the mean flow and eventually filled in. The model simulated the flow directions, the generation (or not) of rip currents, and the morphological evolution of the channels reasonably well. Model simulations were then conducted for different combinations of the two channel geometries and two wave conditions to examine the relative importance of the waves and morphology to the rip current evolution. The different bathymetries were the dominant factor controlling the flow, whereas both the initial morphology and wave conditions were important for channel evolution. In addition, channel dimensions affected the spatial distribution of rip current forcings and the relative importance of terms.

中文翻译：

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水深测量和波浪在裂谷动力学中的作用

离岸流（强烈的、波浪驱动的近海定向海流）的行为和可预测性已经被研究了几十年。然而，很少有研究探讨裂隙通道形态对裂隙生成的影响，或将形态动力学模型与观测结果进行比较。在这里，使用数值形态动力学模型 MIKE21 进行的模拟再现了在美国北卡罗来纳州达克附近的海滩上疏浚的两个河道的流量和测深演变趋势。两种情况下的河道尺寸、波浪条件和流量不同。在一种情况下，强大的离岸流是由中等高度、接近垂直入射的波浪驱动的，在大约 1 米深的通道上，测深演化相对较小。在另一种情况下，较浅（∼0.5 m）河道上的大的、接近垂直入射的波浪不会产生裂隙，并且河道沿平均水流方向迁移并最终被填充。该模型模拟了水流方向、离岸流的产生（或不产生）以及河道的形态演化都相当不错。然后对两个通道几何形状和两种波浪条件的不同组合进行模型模拟，以检查波浪和形态对离岸流演化的相对重要性。不同的水深是控制水流的主导因素，而初始形态和波浪条件对于河道演化都很重要。此外，河道尺寸影响离岸流强迫的空间分布和项的相对重要性。