Abstract The prediction of wave runup, as well as its components, time-averaged setup and the time-varying swash, is a key element of coastal storm hazard assessments, as wave runup controls the transitions between morphodynamic response types such as dune erosion and overwash, and the potential for flooding by wave overtopping. While theoretically able to simulate the dominant low-frequency swash, previous studies using the infragravity-wave–resolving model XBeach (XBSB) have shown an underestimation of the observed swash variance and wave runup, which was in part related to the absence of incident-band swash motions in the model. Here, we use an incident-band wave-resolving, non-hydrostatic version of the XBeach model (XBNH) to simulate wave runup on an intermediate–reflective sandy beach observed during the SandyDuck ’97 experiment. The results show that the XBNH model describes wave runup and the individual setup and swash components well. We subsequently examine differences in wave runup prediction between the XBSB and XBNH models and find that the XBNH model is a better predictor of wave runup than XBSB for this beach, which is due to better predictions of both the incident-band and infragravity-band swash. For a range of beach states from reflective to dissipative it is shown that incident-band swash is underestimated by XBSB relative to XBNH, in particular for reflective conditions. Infragravity-band swash is shown to be lower in XBSB than XBNH for most conditions, including dissipative conditions for which the mean difference is 16% of the deep water wave height. The difference in infragravity-band swash in XBNH relative to XBSB is shown to mainly be the result of processes occurring outside the swash zone, but approximately 15% of the difference is caused by explicitly resolving incident-band wave motions within the swash zone, such as swash-swash interactions, which inherently cannot be simulated by wave-averaged models.

中文翻译：

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使用 XBeach 的波浪解析和波浪平均版本模拟中间反射海滩上的波浪爬高

摘要 波浪爬高的预测及其组成部分、时间平均设置和时变冲刷是沿海风暴灾害评估的关键要素，因为波浪爬高控制着沙丘侵蚀和冲刷等形态动力学响应类型之间的转换。 ，以及海浪淹没的可能性。虽然理论上能够模拟主要的低频斜波，但先前使用超引力波解析模型 XBeach (XBSB) 的研究表明，观察到的斜波方差和波爬高被低估了，这在一定程度上与没有入射-模型中的带状斜盘运动。在这里，我们使用 XBeach 模型 (XBNH) 的入射带波分辨、非静水力版本来模拟 SandyDuck '97 实验期间观察到的中间反射沙滩上的波浪上升。结果表明，XBNH 模型很好地描述了波浪爬高以及单独的设置和斜盘分量。我们随后检查了 XBSB 和 XBNH 模型之间波浪爬高预测的差异，并发现 XBNH 模型比 XBSB 更能预测该海滩的波浪爬高，这是由于对入射带和次重力带斜波的预测更好. 对于从反射到耗散的一系列海滩状态，表明 XBSB 相对于 XBNH 低估了入射带倾斜，特别是对于反射条件。在大多数条件下，XBSB 中的超重力带斜率低于 XBNH，包括平均差异为深水波高度 16% 的耗散条件。