Suspended Sediment Dynamics in the Macrotidal Seine Estuary (France): 2. Numerical Modeling of Sediment Fluxes and Budgets Under Typical Hydrological and Meteorological Conditions
Suspended Sediment Dynamics in the Macrotidal Seine Estuary (France): 2. Numerical Modeling of Sediment Fluxes and Budgets Under Typical Hydrological and Meteorological Conditions
复制标题
大潮汐塞纳河口的悬浮泥沙动力学（法国）：2.典型水文和气象条件下泥沙通量和收支的数值模拟
DOI：
10.1002/2016jc012638
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发表时间：
2017
影响因子：
--
通讯作者：
B. Thouvenin
中科院分区：
文献类型：
--
作者：
E. Schulz;F. Grasso;P. Hir;R. Verney;B. Thouvenin
了解河口的沉积物动力学对于其形态动力学和生态评估以及在人为控制系统的情况下对其维护非常重要。然而，根据现场数据量化沉积物通量和预算极其困难，需要经过彻底验证的数值模型。在此提出的研究中，根据实际的水文和气象条件，对塞纳河下游河口的沉积物通量和预算进行了量化和研究，从季节到年度时间尺度。使用基于现实三维过程的水文和沉积物动力学模型来量化通过特征河口横截面的泥浆和沙子通量。除了具有典型强迫的参考实验之外，还进行了三个实验并进行了分析，每个实验在河流流量或风浪方面都与参考实验不同，以便可以区分这些强迫的影响。水文和气象条件以不同方式和在不同地点影响沉积物通量和收支。单一风暴事件会对河口下游造成强烈侵蚀，并对塞纳河口近海沉积物通量产生显着影响，通量方向取决于风向。大潮在河口引起显着的河口上游通量。河流流量大，在上断面驱动正压河口下游通量，但在河口和近海则驱动斜压河口上游通量，使得下游河口在潮湿年份获得沉积物。这种行为很可能在全世界受密度梯度和浊度最大动态影响的河口中观察到。
Understanding the sediment dynamics in an estuary is important for its morphodynamic and ecological assessment as well as, in case of an anthropogenically controlled system, for its maintenance. However, the quantification of sediment fluxes and budgets is extremely difficult from in-situ data and requires thoroughly validated numerical models. In the study presented here, sediment fluxes and budgets in the lower Seine Estuary were quantified and investigated from seasonal to annual time scales with respect to realistic hydro- and meteorological conditions. A realistic three-dimensional process-based hydro- and sediment-dynamic model was used to quantify mud and sand fluxes through characteristic estuarine cross-sections. In addition to a reference experiment with typical forcing, three experiments were carried out and analysed, each differing from the reference experiment in either river discharge or wind and waves so that the effects of these forcings could be separated. Hydro- and meteorological conditions affect the sediment fluxes and budgets in different ways and at different locations. Single storm events induce strong erosion in the lower estuary and can have a significant effect on the sediment fluxes offshore of the Seine Estuary mouth, with the flux direction depending on the wind direction. Spring tides cause significant up-estuary fluxes at the mouth. A high river discharge drives barotropic down-estuary fluxes at the upper cross-sections, but baroclinic up-estuary fluxes at the mouth and offshore so that the lower estuary gains sediment during wet years. This behaviour is likely to be observed worldwide in estuaries affected by density gradients and turbidity maximum dynamics.