Abstract The calibrated foredunes of the Aquitaine coast (SW France) constitute an example of secular extensive application of nature-based solution. Being one of the longest and largest dune systems in Europe, this iconic landscape offers considerable services to coastal societies. Since the mid-half of the 18th century, human work on sediment flows has resulted in the emergence of large sets of foredunes, currently constituting an almost 230 km-long managed barrier against inland sand invasion, coastline erosion, coastal flooding and also a major reserve of biodiversity. Last massive mechanic shaping of the foredunes following a so-called “ideal profile” date back to the 1970s–80s and aimed to limit erosion dynamics and sediment mobility. Since, they have been facing multiples disruptions over the years which have considerably modified their morphology, especially during the last decades. Calibrated foredunes are currently exhibiting impressive dimensions with a mean dune height of about 16.6 m (peaking at >30 m in some locations) and a dune width mean along the coast of 187 m. Today, 55.5% of them meet the “ideal profile” shape standards or surpass the in terms of dimensions whereas 21,5% of the calibrated foredunes are considered “narrowed” and need specific attention. This regional analysis, based on extensive airborne LiDAR datasets from 2011 to 2018, includes (i) a dune morphology classification based on several basic geomorphological indicators (dune width, height, crest position, back dune elevation) compared to a calibrated “idealised” shaped profile, (ii) a quantification of marine beach-dune and aeolian sediments flows (in m/year and m/m2/year) and forms on dunes (scarps, blowouts, depositional lobes), as an indicator of the recent dynamics affecting dune morphology and (iii) a study of management control of calibrated foredunes (4613 interventions) including actions taken after the outstanding winter of 2013–2014. As expected, intensive dune management are mainly focused where assets are directly threatened. The study highlights the importance and the efficiency of human management on dune evolutions (long term dune form stability, control of gullies and incipient frontal blowout after marine erosion, protection of human issues). However, today management actions (wind fence, branch cover, planting and reshaping) are not conditioned by foredune morphology or last decade's beach-dune dynamic (sediment availability, chronic coastline erosion). Considering long-term erosion projections and expected impact of climate change, the analysis shows the need of more global and extensive strategies in order to preserve the protection role of foredunes in the coming decades.

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法国西南海岸管理沙丘地貌特征与演化

摘要 阿基坦海岸（法国西南部）的校准前哨构成了基于自然的解决方案长期广泛应用的一个例子。作为欧洲最长和最大的沙丘系统之一，这一标志性景观为沿海社会提供了可观的服务。自 18 世纪中叶以来，人类在泥沙流方面的工作导致了大量前沙的出现，目前构成了近 230 公里长的管理屏障，可抵御内陆沙土入侵、海岸线侵蚀、沿海洪水，也是一个主要的生物多样性保护区。根据所谓的“理想剖面”进行的最后一次大规模机械塑造可以追溯到 1970 年代至 80 年代，旨在限制侵蚀动力学和沉积物流动性。自从，多年来，它们一直面临着多次破坏，这极大地改变了它们的形态，尤其是在过去的几十年里。校准前沙丘目前表现出令人印象深刻的尺寸，平均沙丘高度约为 16.6 m（在某些位置达到 >30 m），沿海岸的沙丘宽度平均值为 187 m。今天，其中 55.5% 的前足符合“理想轮廓”形状标准或超过尺寸，而 21.5% 的校准前足被认为是“狭窄的”，需要特别注意。该区域分析基于 2011 年至 2018 年广泛的机载 LiDAR 数据集，包括 (i) 基于几个基本地貌指标（沙丘宽度、高度、顶部位置、沙丘后高程）的沙丘形态分类与校准的“理想化”形状轮廓，(ii) 对海洋沙滩沙丘和风成沉积物流量（以米/年和米/平方米/年为单位）和沙丘上的形式（悬崖、井喷、沉积裂片）的量化，作为影响沙丘形态的近期动态的指标和(iii) 校准前期（4613 次干预）的管理控制研究，包​​括在 2013-2014 年寒冬过后采取的行动。正如预期的那样，集约化沙丘管理主要集中在资产受到直接威胁的地方。该研究强调了人类管理对沙丘演化的重要性和效率（沙丘形态的长期稳定性、海蚀后沟壑和初期正面井喷的控制、人类问题的保护）。然而，今天的管理行动（风栅栏、树枝覆盖、种植和整形）不受前兆形态或过去十年的限制' s 海滩沙丘动态（沉积物可用性，慢性海岸线侵蚀）。考虑到长期侵蚀预测和气候变化的预期影响，分析表明需要更多全球性和更广泛的战略，以在未来几十年保持前序的保护作用。