Beach loss is a growing global challenge that threatens the safety of coastal communities, the health of coastal ecosystems, recreational amenities, and regional economies dependent on tourism. Spatial gradients in longshore sediment transport, or divergence of drift (DoD), is a primary driver of beach width change over multi-annual time scales, but the response of any particular beach can be challenging to characterize and predict. Here we present a new method to characterize DoD using a non-uniform segmentation of the coastline informed by the spatial distribution of longshore transport potential, including the location of physical barriers identified using satellite imagery, and both maxima and reversals in longshore transport potential derived from nearshore wave data. The method demonstrates improved capacity to predict beach width trends at sandy beaches compared to methods that rely on a uniform segmentation of the coastline. In an application to southern California where satellite data documents two decades of beach width change, the non-uniform segmentation method correctly predicts the sign of beach trends at 93% of transects within a littoral cell and achieves a linear correlation between DoD and beach width trends exceeding 0.8. Moreover, we find that a minimum of five years of data are required to establish consistently strong correlations between DoD and beach width changes. Conversely, use of a uniform segmentation is shown to be unreliable for estimating beach width trends due to strong sensitivities to shoreline segment size. This work shows the potential to leverage nearshore wave data and satellite-based beach width data for improved characterization of shoreline dynamics relevant to beach erosion management.

中文翻译：

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描述沿岸运输潜力和漂移差异，以了解海滩损失趋势

海滩流失是一个日益严重的全球性挑战，威胁着沿海社区的安全、沿海生态系统的健康、娱乐设施以及依赖旅游业的区域经济。沿岸沉积物迁移的空间梯度或漂移散度 (DoD) 是多年时间尺度上海滩宽度变化的主要驱动因素，但任何特定海滩的响应都难以表征和预测。在这里，我们提出了一种新方法来描述国防部的特征，该方法使用海岸线的非均匀分割，该分割由沿海运输潜力的空间分布提供信息，包括使用卫星图像识别的物理障碍的位置，以及从以下数据得出的沿海运输潜力的最大值和逆转近岸波浪数据。与依赖海岸线统一分割的方法相比，该方法显示出预测沙滩宽度趋势的能力有所提高。在南加州的应用中，卫星数据记录了二十年的海滩宽度变化，非均匀分割方法正确预测了沿海单元内 93% 的横断面的海滩趋势符号，并实现了 DoD 和海滩宽度趋势之间的线性相关性超过0.8。此外，我们发现至少需要五年的数据才能在国防部和海滩宽度变化之间建立一致的强相关性。相反，由于对海岸线段尺寸的强烈敏感性，使用统一分割来估计海滩宽度趋势是不可靠的。这项工作显示了利用近岸波浪数据和基于卫星的海滩宽度数据来改进与海滩侵蚀管理相关的海岸线动态特征的潜力。