Modelling-based assessment of suspended sediment dynamics in a hypertidal estuarine channel
Modelling-based assessment of suspended sediment dynamics in a hypertidal estuarine channel
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DOI：
10.1007/s10236-014-0695-8
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发表时间：
2014-04
期刊：
影响因子：
2.3
通讯作者：
L. Amoudry;Rafael Ramírez-Mendoza;A. Souza;Jennifer M. Brown
中科院分区：
文献类型：
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作者：
L. Amoudry;Rafael Ramírez-Mendoza;A. Souza;Jennifer M. Brown
本文研究了高潮河口河道中垂直剪切交换流的悬沙输运动力学。我们应用三维过程为基础的模型耦合水动力学，湍流和泥沙输运的迪河口，在英国西北地区。数值模式是用来重现悬浮泥沙观测和评估物理过程负责所观察到的悬浮泥沙浓度模式。研究期间的重点是平静期，在此期间波流相互作用可以合理地忽略不计。模型与观测结果符合较好。一系列的数值试验的目的是隔离特定的过程，并确认悬浮泥沙动力学的结果主要来自平流的纵向浓度梯度在我们的研究期间，再悬浮和垂直交换过程相结合。沉积物的水平平流呈现出强烈的半日变化，而垂直交换过程（包括随时间变化的沉降作为絮凝的代理）表现出四分之一昼夜变化。从河流中的泥沙输入被发现有很小的重要性，悬浮浓度的空间梯度所产生的空间异质性，在河床沉积物的特性和空间变化的湍流和床剪切应力。
We investigate the dynamics of suspended sediment transport in a hypertidal estuarine channel which displays a vertically sheared exchange flow. We apply a three-dimensional process-based model coupling hydrodynamics, turbulence and sediment transport to the Dee Estuary, in the north-west region of the UK. The numerical model is used to reproduce observations of suspended sediment and to assess physical processes responsible for the observed suspended sediment concentration patterns. The study period focuses on a calm period during which wave-current interactions can reasonably be neglected. Good agreement between model and observations has been obtained. A series of numerical experiments aim to isolate specific processes and confirm that the suspended sediment dynamics result primarily from advection of a longitudinal gradient in concentration during our study period, combined with resuspension and vertical exchange processes. Horizontal advection of sediment presents a strong semi-diurnal variability, while vertical exchange processes (including time-varying settling as a proxy for flocculation) exhibit a quarter-diurnal variability. Sediment input from the river is found to have very little importance, and spatial gradients in suspended concentration are generated by spatial heterogeneity in bed sediment characteristics and spatial variations in turbulence and bed shear stress.