Projections of high rates of sea level rise have stimulated proposals for adaptation strategies with increasingly high nourishment volumes along sandy beaches. An underlying assumption is that coastal profiles respond rapidly to nourishments by redistributing sediments towards a (new) equilibrium shape. However, this perception may not be valid when high volumes of nourishment are applied, as the profile shape may then undergo significant deformation. Current state-of-the-art modelling techniques often concentrate on a single spatio-temporal scale, either lacking the necessary temporal horizon or failing to provide the required level of cross-shore detail. This article introduces Crocodile, a diffusion based cross-shore model designed to bridge the gap between short- and long-term nourishment modelling. The model simulates the effects of nourishment strategies on coastal volume, coastline position and beach width over a decadal timeframe. It incorporates different elements which compute cross-shore diffusion, sediment exchange with the dune and longshore sediment losses. To test the model performance, a series of idealized nourishment scenarios are examined, along with three case studies along the Dutch coast with different nourishment strategies over the past few decades. The modelled coastal volume, shoreline position and beach width strongly resemble the observations with only a 12% overestimation in profile volume and 13% underestimation in beach width. Averaged over selected periods of nourishment, trends and trend reversals between different strategies are well replicated with slight overestimation for coastal volume trends by , while beach width trends are underestimated by (15%). Given that the added nourishment volumes are typically in the order of , these model errors are considered sufficiently low to conclude that Crocodile effectively simulates variations in coastal volume, coastline position and beach width over a decadal timeframe in response to different nourishment strategies. Therefore, Crocodile can facilitate the evaluation of future nourishment strategies.

中文翻译：

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使用 Crocodile 模拟滋养海岸的十年跨岸动态

海平面快速上升的预测刺激了人们提出适应策略，要求沙滩上的营养量不断增加。一个基本假设是，沿海剖面通过将沉积物重新分布到（新的）平衡形状来对营养物做出快速反应。然而，当施加大量营养时，这种看法可能无效，因为轮廓形状可能会发生显着变形。当前最先进的建模技术通常集中在单个时空尺度上，要么缺乏必要的时间范围，要么无法提供所需的跨岸细节水平。本文介绍了 Crocodile，这是一种基于扩散的跨岸模型，旨在弥合短期和长期营养模型之间的差距。该模型模拟了十年时间内营养策略对沿海体积、海岸线位置和海滩宽度的影响。它包含了计算跨岸扩散、沙丘沉积物交换和沿岸沉积物损失的不同元素。为了测试模型的性能，我们检查了一系列理想的营养场景，以及过去几十年荷兰海岸沿线采用不同营养策略的三个案例研究。建模的海岸体积、海岸线位置和海滩宽度与观测结果非常相似，剖面体积仅高估了 12%，海滩宽度低估了 13%。对选定的滋养期进行平均，不同策略之间的趋势和趋势反转得到了很好的复制，沿海体积趋势略微高估了 ，而海滩宽度趋势则被低估了 (15%)。鉴于添加的营养量通常约为 ，这些模型误差被认为足够低，可以得出结论，鳄鱼有效地模拟了十年时间范围内沿海体积、海岸线位置和海滩宽度的变化，以响应不同的营养策略。因此，鳄鱼可以帮助评估未来的营养策略。