Physical response of a back-barrier estuary to a post-tropical cyclone
Physical response of a back-barrier estuary to a post-tropical cyclone
复制标题
后障壁河口对热带气旋后的物理响应
DOI：
10.1002/2016jc012344
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发表时间：
2017
影响因子：
--
通讯作者：
A. Aretxabaleta
中科院分区：
文献类型：
--
作者：
Alexis Beudin;N. Ganju;Z. Defne;A. Aretxabaleta
本文利用COAWST系统模拟了美国弗吉尼亚州钦科蒂格湾（Chincoteague Bay，VA/MD）对飓风桑迪的水动力和泥沙输运响应。进行了几个模拟方案，以确定主要的物理过程，其中包括远程和本地力量的不同组合。虽然80%的水位增加，在海湾是由于沿海海平面在风暴的高峰，丰富的空间和时间变化的水面坡度是由当地的风和波浪。当地风增加了垂直混合，水平交换，并通过入口冲洗。远程波（涌浪）通过波设置入口之间的梯度增强向南流动，并增加当地产生的波高。当地产生的波浪对水位的影响可以忽略不计，但由于表观粗糙度和破碎诱导力的增强，剩余流量减少了70%。局部生成的波浪主导了海湾的床面剪切应力和沉积物再悬浮。沉积物迁移模式反映了内陆海岸线的形状，并在淹没地区产生沉积。该海湾是内陆架细沉积物的来源，而面向海洋的屏障岛则是由向陆地的过冲形成的积沙。尽管风暴的强度很大，但海湾的水深变化仍在厘米级。这项工作展示了风暴强迫的反应谱，并强调了当地和远程过程对后障河口功能的重要性。
This paper presents a modeling investigation of the hydrodynamic and sediment transport response of Chincoteague Bay (VA/MD, USA) to Hurricane Sandy using the Coupled Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) modeling system. Several simulation scenarios with different combinations of remote and local forces were conducted to identify the dominant physical processes. While 80% of the water level increase in the bay was due to coastal sea level at the peak of the storm, a rich spatial and temporal variability in water surface slope was induced by local winds and waves. Local wind increased vertical mixing, horizontal exchanges, and flushing through the inlets. Remote waves (swell) enhanced southward flow through wave setup gradients between the inlets, and increased locally generated wave heights. Locally generated waves had a negligible effect on water level but reduced the residual flow up to 70% due to enhanced apparent roughness and breaking-induced forces. Locally generated waves dominated bed shear stress and sediment resuspension in the bay. Sediment transport patterns mirrored the interior coastline shape and generated deposition on inundated areas. The bay served as a source of fine sediment to the inner shelf, and the ocean-facing barrier island accumulated sand from landward-directed overwash. Despite the intensity of the storm forcing, the bathymetric changes in the bay were on the order of centimeters. This work demonstrates the spectrum of responses to storm forcing, and highlights the importance of local and remote processes on back-barrier estuarine function.