Storm-Impact Scenario XBeach Model Results – Scenario 2 Digital Elevation Model (DEM) Grid

The numerical model XBeach (version 4937) was used to investigate how different storm scenarios impact the sediment berm constructed offshore of the Chandeleur Islands and adjacent areas. The XBeach model solves coupled 2-dimensional, horizontal wave propagation equations to predict flow, sediment transport, and bottom changes for varying spectral wave and flow boundary conditions (Roelvink and others, 2009 ). The XBeach model setup requires the input of a merged topographic and bathymetric DEM, and inputs of wave spectra (based on significant wave height, peak wave period, and wave direction) and water level (tide and surge) time series at the seaward model boundary that span the duration of each storm bin. The Xbeach model input and output of topography and bathymetry resulting from simulation of storm-impact scenarios at the Chandeleur Islands, LA, as described in USGS Open-File Report 2017–1009 are provided via a USGS data release (storm scenario bins where no events were observed are excluded). For further information regarding model input generation and visualization of model output topography and bathymetry, refer to Mickey and others (2017).

本研究采用数值模型XBeach（版本4937），探究不同风暴情景对尚德勒尔群岛离岸海域及邻近区域的沉积物滩脊的影响。XBeach模型通过求解耦合二维水平波浪传播方程，可针对不同的谱波浪与流场边界条件，模拟预测流场、泥沙输运及底床变化（Roelvink等，2009）。XBeach模型的搭建需输入融合地形与水深的数字高程模型（Digital Elevation Model，DEM），同时需在模型向海边界输入覆盖各风暴分箱持续时长的波浪谱（基于有效波高、峰值波周期与波浪方向）以及水位（潮汐与风暴增水）时间序列。针对路易斯安那州尚德勒尔群岛风暴影响情景开展模拟所得到的XBeach模型输入数据，以及模拟生成的地形与水深数据，均已通过美国地质调查局（United States Geological Survey，USGS）数据发布渠道公开，相关内容详见该机构2017–1009号开放文件报告；其中未观测到事件的风暴分箱情景已被剔除。如需了解模型输入数据生成及模型输出地形与水深数据可视化的更多细节，请参考Mickey等（2017）的研究。