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Storm-induced hydrodynamic changes and seabed erosion in the littoral area of Yellow River Delta: A model-guided mechanism study
Continental Shelf Research ( IF 2.3 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.csr.2020.104171
Yaoshen Fan , Shenliang Chen , Shunqi Pan , Shentang Dou

Abstract Morphological evolution of large river deltas is highly vulnerable to extreme storm events due to insufficient sediment supply. As an abandoned delta lobe, the coasts along the northern Yellow River Delta (YRD) and Gudong Oil Field have recently suffered serious erosion due to extreme storm events and become increasingly vulnerable. In this study, a well validated and tested Delft 3D module by the observing hydrodynamic and sediment data to simulate the hydrodynamics and seabed erosion during a storm event in the littoral area of YRD. Observed wave, current and sediment data under both fair-weather and storm conditions were collected in the study area and used to validate the model. The results indicated that the model can reproduce well the hydrodynamic and sediment transport processes. A series of numerical experiments were carried out to examine the hydrodynamic changes and sediment transports. In the numerical experiment of normal condition, there is hardly any sediment transport off the YRD. The numerical experiment of storm condition showed that storms enhanced tidal residual currents, weakened tidal shear front, and significant wave heights up to 2 m, considerably intensified the sediment resuspension and dispersal. The local sediment resuspension due to the increased wave-induced bottom stress promoted the sediment plume to expand to the central area of Laizhou Bay, which seemed to provide sediment source for offshore and southward transport. During the storm, the active nearshore sediment resuspension provided sediment source for offshore and southward transport. The intensive dynamics and sediment transport under storm conditions caused significant changes in seabed erosion and siltation. The main erosion occurred off the Gudong and northern YRD, while the main siltation appeared in the central area of Laizhou Bay. No significant recovery after a storm and frequent strong winds have an accumulative effect on the erosion, which is very likely to dominate the erosive states of the YRD coast in the future.

中文翻译:

黄河三角洲沿岸地区风暴引起的水动力变化和海底侵蚀:模型引导的机制研究

摘要 由于沉积物供应不足,大型河流三角洲的形态演变极易受到极端风暴事件的影响。作为一个废弃的三角洲叶,黄河三角洲北部(YRD)和古东油田沿岸最近因极端风暴事件而遭受严重侵蚀,变得越来越脆弱。在这项研究中,一个经过充分验证和测试的代尔夫特 3D 模块通过观察水动力和沉积物数据来模拟长三角沿岸地区风暴事件期间的水动力和海床侵蚀。在研究区收集了在晴朗天气和风暴条件下观测到的波浪、洋流和沉积物数据,并用于验证模型。结果表明,该模型能够较好地再现水动力和泥沙输移过程。进行了一系列数值实验来研究水动力变化和泥沙输移。在正常条件下的数值试验中,长三角地区几乎没有泥沙运移。风暴工况数值试验表明,风暴增强了潮汐残余流,减弱了潮汐切变锋,显着波高可达2 m,显着加剧了沉积物的再悬浮和扩散。波浪引起的底应力增加导致局部沉积物再悬浮,促使沉积物羽流向莱州湾中心区扩张,这似乎为近海和向南输送提供了沉积物来源。在风暴期间,活跃的近岸沉积物再悬浮为近海和向南输送提供了沉积物来源。风暴条件下的强烈动力学和沉积物输送导致海底侵蚀和淤积的显着变化。主要侵蚀发生在古东和长三角北部,而主要淤积发生在莱州湾中部地区。暴风雨后无明显恢复,强风频发对侵蚀产生累积效应,未来很可能主导长三角沿岸的侵蚀状态。
更新日期:2020-12-01
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