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首页> 外文期刊>Estuarine Coastal and Shelf Science >Contribution of hydrodynamic conditions during shallow water stages to the sediment balance on a tidal flat: Mont-Saint-Michel Bay, Normandy, France
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Contribution of hydrodynamic conditions during shallow water stages to the sediment balance on a tidal flat: Mont-Saint-Michel Bay, Normandy, France

机译：浅水阶段水动力条件对潮滩沉积物平衡的贡献：法国诺曼底山圣米歇尔山

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摘要

Field measurements were conducted in Mont-Saint-Michel Bay, a megatidal embayment (spring tidal range of 15 m), in order to monitor, over the course of a tidal cycle, sediment transport variability due to waves and tides on the upper part of a tidal flat characterised by shallow water depths. Sensors used to measure currents, water depth and turbidity were installed just above the bed (0.04 m). Two experiments were conducted under contrasting hydrodynamic conditions. The results highlight wave activity over the tidal flat even though observed wind waves were largely dissipated due to the very shallow water depths. Very high suspended sediment concentrations (up to 6 kg/m~3) were recorded in the presence of wave activity at the beginning of the local flood, when significant sediment transport occurred, up to 7 times as much as under conditions of no wave activity. This influence may be attributed to the direct action of waves on bed sediments, to wave-induced liquefaction, and to the erosive action of waves on tidal channel banks. The sediment composition, comprising a clay fraction of 2—5%, may also enhance sediment transport by reducing critical shear stress through the sand lubrication effect. The results also show that antecedent meteorological conditions play an important role in suspended sediment transport on the tidal flat. Total sediment flux directions show a net transport towards the inner part of the bay that contributes to deposition over the adjacent salt marshes, and this tendency also prevails during strong wave conditions. Such sediment transport is characterised by significant variability over the course of the tidal cycle. During fair and moderate weather conditions, 83% and 71% of the total flux was observed, respectively, over only 11 % and 28% of the duration of the local tidal cycle and with water depths between 0.04 and 0.3 m. These results suggest that in order to improve our understanding of sediment budgets in this type of coastal environment, it is essential to record data just at the beginning and at the end of tidal submergence close to the bed.
机译：实地测量是在一个大型潮汐带（圣潮米范围为15 m）的圣米歇尔山湾进行的，目的是在潮汐过程中监测由于潮汐和潮汐引起的沉积物运移变化。以浅水深度为特征的潮滩。用于测量水流，水深和浊度的传感器安装在床身上方（0.04 m）。在相反的流体动力学条件下进行了两个实验。结果表明，尽管观察到的风浪由于水深很浅而在很大程度上消散，但潮汐平面上的波浪活动仍然突出。在局部洪水开始时有波浪活动时，记录到很高的悬浮沉积物浓度（高达6 kg / m〜3），这时发生了显着的沉积物运移，是无波浪活动条件下的七倍之多。 。这种影响可能归因于波浪对河床沉积物的直接作用，波浪引起的液化以及波浪对潮汐河岸的侵蚀作用。包含2％至5％粘土含量的沉积物成分还可以通过降低砂土润滑作用的临界剪切应力来增强沉积物的运输。结果还表明，先前的气象条件在潮滩上的悬浮泥沙输送中起着重要作用。总的泥沙通量方向显示出向海湾内部的净输运，这有助于在相邻的盐沼上沉积，这种趋势在强波浪条件下也很普遍。这种沉积物的输送的特征是在潮汐周期的过程中存在明显的变化。在中等和适度的天气条件下，分别观察到总通量的83％和71％，仅占当地潮汐周期持续时间的11％和28％，水深在0.04至0.3 m之间。这些结果表明，为了增进我们对这种沿海环境中沉积物预算的理解，至关重要的是仅在靠近床层的潮汐淹没开始和结束时记录数据。

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  • 来源
    《Estuarine Coastal and Shelf Science》 |2011年第4期|p.343-354|共12页
  • 作者

    R. Desguee; N. Robin; L Gluard; O. Monfort; E.J. Anthony; F. Levoy;

  • 作者单位

    Unite Morphodynamique Continentale et Cotiere, Universite de Caen - Basse-Normandie, 2-4 rue des Tilleuls, 14000 Caen Cedex, France;

    Unite Morphodynamique Continentale et Cotiere, Universite de Caen - Basse-Normandie, 2-4 rue des Tilleuls, 14000 Caen Cedex, France;

    Unite Morphodynamique Continentale et Cotiere, Universite de Caen - Basse-Normandie, 2-4 rue des Tilleuls, 14000 Caen Cedex, France;

    Unite Morphodynamique Continentale et Cotiere, Universite de Caen - Basse-Normandie, 2-4 rue des Tilleuls, 14000 Caen Cedex, France;

    Centre Europeen de Recherche et d'Enseignement des Geosaences de I'Environnement, Universite d'Aix-Marseille, Institut Universitaire de France,Europole Mediterraneen de I'Arbois, 13545 Aix-en-Provence cedex 04, France;

    Unite Morphodynamique Continentale et Cotiere, Universite de Caen - Basse-Normandie, 2-4 rue des Tilleuls, 14000 Caen Cedex, France;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    tidal flat; megatidal environment; sediment transport; turbidity; w ave action; s hallow water; f rance; mont-saint-michel bay;

    机译：潮滩;潮汐环境泥沙输送;浑浊;波动;圣水;法国;圣米歇尔山湾;

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