Coastal erosion under the context of global sea-level rise has threatened societies living along the coast. The processes related to decadal- to centennial-scale shoreline changes are much more complex than those suggested by the Bruun effect. This paper derives a one-dimensional model to explore the relationships between shoreline change, profile concavity, and sediment fluxes in wave-dominated coastal systems where alongshore sediment transport dominates the shoreline changes. The model incorporates an exponential approximation of shoreface profiles into the shoreline Exner equation. We found an equilibrium relationship in which a stable morphology profile is maintained during synchronous changes in sediment loss (gain) and shoreline retreat (advance) distances. Complex shoreline retreat behaviours can be classified into two dynamic equilibrium cases that are either above or below this equilibrium relationship. For a given negative net sediment flux, the shoreline retreat slows when the shoreface morphology steepens (i.e. increased profile concavity), and vice versa. Likewise, for a given positive net sediment flux, the shoreline advance slows when the shoreface morphology becomes gentle (i.e. decreased profile concavity), and vice versa. Interestingly, the higher the net sediment flux is, the greater the influence of shoreline changes on shoreface morphology. The short- and long-term processes governing the shoreface morphological changes are also discussed. This study demonstrates the importance of shoreface morphological concavity on the shoreline changes. Furthermore, the presented first-order model might have the potential to be used as a quick assessment for future decadal- to centennial-scale shoreline changes in coastal management and engineering activities.

中文翻译：

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评估岸面剖面凹度对长期海岸线变化的影响：一项探索性研究

全球海平面上升背景下的海岸侵蚀威胁着沿海社会。与十年到百年规模的海岸线变化相关的过程比布鲁恩效应所暗示的过程复杂得多。本文推导了一个一维模型，以探讨在波浪主导的沿海系统中，海岸线变化、剖面凹度和沉积物通量之间的关系，其中沿岸沉积物运输主导着海岸线变化。该模型将岸面剖面的指数近似合并到海岸线 Exner 方程中。我们发现了一种平衡关系，其中在沉积物损失（增加）和海岸线后退（前进）距离的同步变化期间保持稳定的形态剖面。复杂的海岸线撤退行为可分为高于或低于该平衡关系的两种动态平衡情况。对于给定的负净泥沙通量，当岸面形态变陡（即剖面凹度增加）时，岸线后退减慢，反之亦然。同样，对于给定的正净沉积物通量，当岸面形态变得平缓（即剖面凹度减小）时，海岸线前进减慢，反之亦然。有趣的是，净泥沙通量越高，岸线变化对岸面形态的影响越大。还讨论了控制岸面形态变化的短期和长期过程。本研究证明了岸面形态凹度对岸线变化的重要性。此外，