Abstract The objective of this study was to evaluate the temporal and spatial performance of the XBeach model predicting storm surge-induced erosion and breaching on the basis of a two-dimensional field case. Within the scope of a physical experiment, a large-scale artificial unvegetated research dune was built at the German Baltic Sea Coastline and surveyed before, during and after a surge event to generate high-resolution digital elevation models of the temporal and spatial failure process. The measured data was used to set-up and calibrate two-dimensional XBeach models. The numerical results showed that the default settings of the latest XBeach-X release led to a very good agreement (BSS = 0.82) between the simulated and measured post-storm bed levels in the area of the research dune, while a higher agreement was observed on the overwash and inundation dominant eastern side than on the collision dominant western side. Evaluating the model accuracy during the storm surge using 44 digital elevation models of the seaside slope showed a spatially accurate prediction of the two observed breaches (±5 m) but also the occurrence of additional breaches. With respect to timing and breach width evolution, however, the results highly deviated from the observation and were found to be very sensitive to changes in grid resolution and to changes of default parameters. Exchanging the nearshore bathymetry with measurements one and two months prior to the physical experiment, where a 49% and 51% lower subaerial beach volume was observed, resulted in a significantly overestimated dune erosion (31% and 33%) and, hence, in a lower accuracy of the default model (BSS = 0.69). Overall, the XBeach model is capable of accurately predicting the evolution of storm-induced erosion during a sufficiently long and overwash/inundation-dominant surge event when current high-resolution input data is available.

中文翻译：

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基于包括人工无植被研究沙丘在内的二维现场案例的风暴侵蚀模型的时空评估

摘要 本研究的目的是评估 XBeach 模型在二维现场案例的基础上预测风暴潮引起的侵蚀和破坏的时空性能。在物理实验范围内，在德国波罗的海海岸线建造了一个大型人工无植被研究沙丘，并在浪涌事件之前、期间和之后进行调查，以生成时空破坏过程的高分辨率数字高程模型。测量数据用于设置和校准二维 XBeach 模型。数值结果表明，最新 XBeach-X 版本的默认设置在研究沙丘区域模拟和测量的风暴后床位之间产生了非常好的一致性（BSS = 0.82），而在以冲刷和淹没为主的东侧比在以碰撞为主的西侧观察到更高的一致性。使用 44 个海边坡度数字高程模型评估风暴潮期间的模型精度，结果表明对两个观测到的裂缝 (±5 m) 以及其他裂缝的发生进行了空间准确的预测。然而，关于时间和裂缝宽度演变，结果与观察结果高度偏离，并且发现对网格分辨率的变化和默认参数的变化非常敏感。将近岸水深测量与物理实验前一两个月的测量值交换，在那里观察到的地下海滩体积降低了 49% 和 51%，导致沙丘侵蚀严重高估（31% 和 33%），因此，默认模型精度较低（BSS = 0.69）。总体而言，当当前的高分辨率输入数据可用时，XBeach 模型能够准确预测风暴引起的侵蚀在足够长且以淹没/淹没为主的浪涌事件期间的演变。