Several studies have highlighted the difficulties inherent to the use of bimodal fluvial sediments in beach nourishment and the resulting unpredictable behaviour of the beach profile. In this paper, we monitored the temporal evolution of a nourishment project carried out on a northwestern Mediterranean beach and using fluvial mixed sand and gravel nourishment material. The main aim of the study was to examine the morpho-sedimentary evolution of the beach from the injection of the nourishment material to the attainment of a targeted equilibrium profile. The monitoring activity was conducted coupling multiple topo-bathymetric surveys and sediment sampling. The data show that the targeted equilibrium profile was attained less than 2 years after the nourishment, and, since that period, the shoreline has shown minimal mobility. Our results show that the positioning of the nourishment material is as important as the correct choice of grain size to attain rapid and successful nourishment of a beach. Further applications of this methodology in other coastal settings and/or with different nourishment sediments (e.g. medium or fine sands) are presently being considered. If confirmed at a broader scale, this nourishment design, employing bimodal fluvial sediments, should significantly contribute to the mitigation of beach erosion.

中文翻译：

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使用双峰河流沉积物和特定放置设计评估地中海海滩的营养功效

几项研究强调了在海滩营养中使用双峰河流沉积物所固有的困难以及由此导致的海滩剖面不可预测的行为。在本文中，我们监测了在地中海西北部海滩上使用河流混合砂砾营养材料进行的营养项目的时间演变。该研究的主要目的是检查海滩从注入营养材料到达到目标平衡剖面的形态沉积演化。监测活动是结合多个地形测深调查和沉积物采样进行的。数据显示，在获得营养后不到 2 年就达到了目标平衡剖面，从那时起，海岸线的流动性很小。我们的结果表明，营养材料的定位与正确选择颗粒大小一样重要，以获得快速和成功的海滩营养。目前正在考虑在其他沿海环境和/或不同营养沉积物（例如中砂或细砂）中进一步应用这种方法。如果在更广泛的范围内得到证实，这种采用双峰河流沉积物的营养设计应该会大大有助于减轻海滩侵蚀。