Abstract Barrier islands are susceptible to erosion, overwash, and breaching during intense storms. However, these processes are not represented typically in large-domain models for storm surge and coastal inundation. In this study, we explore the requirements for bridging the gap between dune-scale morphodynamic and region-scale flooding models. A high-resolution XBeach model is developed to represent the morphodynamics during Hurricane Isabel (2003) in the North Carolina (NC) Outer Banks. The model domain is extended to more than 30 km of Hatteras Island and is thus larger than in previous studies. The predicted dune erosion is in good agreement with post-storm observed topography, and an ‘‘excellent’’ Skill Score of 0.59 is obtained on this large domain. Sensitivity studies show the morphodynamic model accuracy is decreased as the mesh spacing is coarsened in the cross-shore direction, but the results are less sensitive to the alongshore resolution. A new metric to assess model skill, Water Overpassing Area ( W O A ), is introduced to account for the available flow pathway over the dune crest. Together, these findings allow for upscaled parameterizations of erosion in larger-domain models. The updated topography, obtained from XBeach prediction, is applied in a region-scale flooding model, thus allowing for enhanced flooding predictions in communities along the Outer Banks. It is found that, even using a fixed topography in region-scale model, the flooding predictions are improved significantly when post-storm topography from XBeach is implemented. These findings can be generalized to similar barrier island systems, which are common along the U.S. Gulf and Atlantic coasts.

中文翻译：

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风暴驱动的侵蚀和从沙丘到区域尺度的障壁岛淹没

摘要 屏障岛在强烈风暴期间容易受到侵蚀、淹没和破坏。然而，这些过程在风暴潮和沿海淹没的大域模型中通常没有表现出来。在这项研究中，我们探讨了弥合沙丘尺度形态动力学和区域尺度洪水模型之间差距的要求。开发了高分辨率 XBeach 模型来表示北卡罗来纳州 (NC) 外滩的飓风伊莎贝尔 (2003) 期间的形态动力学。模型域扩展到哈特拉斯岛 30 多公里，因此比以前的研究更大。预测的沙丘侵蚀与风暴后观察到的地形非常吻合，在这个大域上获得了 0.59 的“优秀”技能分数。敏感性研究表明，随着跨岸方向的网格间距变粗，形态动力学模型的精度会降低，但结果对沿岸分辨率的敏感性较低。引入了一种评估模型技能的新指标，即越水面积 (WOA)，以说明沙丘顶部的可用流动路径。总之，这些发现允许在更大域模型中对侵蚀进行放大参数化。从 XBeach 预测获得的更新地形应用于区域尺度洪水模型，从而增强外滩沿岸社区的洪水预测。结果表明，即使在区域尺度模型中使用固定地形，在实施 XBeach 风暴后地形时，洪水预测也得到了显着改善。