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首页> 外文期刊>Shore and beach >Effects of natural and human forcing on mesoscale shoreline dynamics of Saint-Michel-en-Greve Bay (Brittany, France)
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Effects of natural and human forcing on mesoscale shoreline dynamics of Saint-Michel-en-Greve Bay (Brittany, France)

机译：自然和人类强迫对Saint-Michel-en-Greve湾（法国布列塔尼）中尺度海岸线动力学的影响

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摘要

By monitoring shoreline changes and subaerial beach volume in Saint-Michel-en-Greve bay in northern Brittany over the past 20 years, the mesoscale shoreline dynamics were assessed. Previous work has shown that both natural and human forcing have played an important role in the long-term changes of the bay, but the respective causes of each type of forcing have not previously been studied in detail. This study shows that between 1990 and 2009, a large volume of sediment input resulted in rapid accretion of dunes in the bay. Sedimentation rates reached an average of 0.1m~3/m~2/yr over the whole study period. This positive sediment budget confirms the trend of sediment accumulation noted since the end of the 19th century. Nevertheless, temporal variation in the shoreline dynamics can be related to changes in the frequency and magnitude of storm surges and resulting high tides. Shoreline erosion/accretion records dating from 1990 were compared with extreme water levels. Relatively high shoreline retreat rates during periods of 1999-2002 and 2006-2008 were associated with a relatively large number of storm surges. Slower erosion and relatively rapid accretion occurred between 1990 and 1999 and during a more recent period, when there have been relatively few major storm surges. Erosion phases were related to the occurrence of extreme spring high tides and wave action associated with storms. Storms and surges in the northern Brittany Channel are associated with Atlantic depressions whose direction and rate of movement have a strong influence on wind speeds, wave energy and the height of tides. However, sediment budget of Saint-Michel-en-Greve bay upper beach, in terms of shoreline erosion/accretion changes, is not directly related to the North Atlantic Oscillation index. Tide condition leading to high or low water level plays a major role by controlling erosion or accretion processes. Human forcing was identified as feedback processes due to the modification of morphological and hydrodynamic conditions. These modifications occurred after coastal engineering works had been carried out on the foreshore to eliminate the confluence of two rivers. West-east longshore sediment transport induced the erosion of the dune of Grand Rocher, while the removed sand contributed to the growth of the dune of Treduder.
机译：通过监测过去20年中布列塔尼北部圣米歇尔恩格里夫湾的海岸线变化和海底海滩体积，对中尺度海岸线动力学进行了评估。先前的工作表明，自然强迫和人为强迫都在海湾的长期变化中发挥了重要作用，但是以前没有详细研究每种强迫类型的各自原因。这项研究表明，在1990年至2009年期间，大量的沉积物输入导致海湾中沙丘的快速积聚。在整个研究期间，平均沉积速率达到0.1m〜3 / m〜2 / yr。积极的泥沙预算证实了自19世纪末以来出现的泥沙积累趋势。然而，海岸线动态的时间变化可能与风暴潮的频率和大小的变化以及由此引起的高潮有关。将1990年以来的海岸线侵蚀/吸水记录与极端水位进行了比较。 1999-2002年和2006-2008年期间海岸线退缩率相对较高，这与风暴潮的数量相对较大有关。较慢的侵蚀和相对较快的增生发生在1990年至1999年之间，以及最近一段时间，当时主要的风暴潮相对较少。侵蚀阶段与极端春季高潮的发生和与风暴有关的波浪作用有关。布列塔尼海峡北部的风暴潮与大西洋低气压有关，大西洋低气压的方向和运动速度对风速，波浪能和潮汐高度有很大影响。然而，就海岸线侵蚀/吸积变化而言，圣米歇尔-en-格里夫湾上海滩的沉积物预算与北大西洋涛动指数没有直接关系。通过控制侵蚀或吸积过程，导致高水位或低水位的潮汐条件起着重要作用。由于形态和流体动力条件的改变，人类强迫被确定为反馈过程。这些修改是在前滨进行了沿海工程以消除两条河流的汇合之后进行的。东西方的近岸沉积物运输引起了大罗彻沙丘的侵蚀，而被清除的沙子促进了特雷杜德沙丘的生长。

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  • 来源
    《Shore and beach》 |2011年第2期|p.19-38|共20页
  • 作者

    Serge Suanez; Pierre Stephan;

  • 作者单位

    GEOMER - UMR 6554 CNRS LETG, Universite de Bretagne Occidentale Institut Universitaire Europeen de la Mer, Technopole Brest-Iroise Place Nicolas Copernic, 29280 Plouzane, France;

    GEOMER - UMR 6554 CNRS LETG, Universite de Bretagne Occidentale Institut Universitaire Europeen de la Mer, Technopole Brest-Iroise Place Nicolas Copernic, 29280 Plouzane, France;

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  • 正文语种 eng
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  • 关键词

    sediment budget; monitoring; shore-line changes; dune erosion; stormsurges; human forcing;

    机译：泥沙预算;监控;海岸线变化;沙丘侵蚀;风暴潮;人类强迫;

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