Abstract This research focuses on the development of a simple and efficient transect based long-term shoreline model. The new modeling tool is a combination of a model for the shoreline changes due to the gradients in longshore drift and a heuristic cross-shore shoreline model. The cross-shore part of the model uses an up-to-date semi-empirical shoreline evolution model based on the equilibrium beach state assumption. A physics-based longshore shoreline model is developed on the same premises as the one-line type approach based on the longshore sand budget and assumes no loss of sediment of the embayed system. The derivation of the longshore part of the model explicitly decouples the average shoreline position from its fluctuating components. An important result is that the equilibrium shoreline orientation is shown to depend on the time correlation between the incoming wave power and the difference between the instantaneous and the time average wave incidence. As a test case, the combined shoreline model is calibrated with the wave and shoreline data of the embayed beach of Narrabeen, Australia. A separate analysis of each contribution reveals that the long-term trend is mostly a longshore drift contribution and surprisingly, part of seasonal shoreline variability is attributed to longshore drift processes.

中文翻译：

---

封闭海湾的海岸线和跨海岸线组合模型

摘要 本研究的重点是开发一种简单有效的基于断面的长期海岸线模型。新的建模工具结合了因沿岸漂移梯度引起的海岸线变化模型和启发式跨海岸海岸线模型。模型的跨海岸部分使用了基于平衡海滩状态假设的最新半经验海岸线演化模型。基于物理的海岸线模型是在与基于海岸沙预算的单线型方法相同的前提下开发的，并假设没有海湾系统的沉积物损失。模型的沿岸部分的推导明确地将平均海岸线位置与其波动分量分离。一个重要的结果是，平衡海岸线方向被证明取决于入射波功率之间的时间相关性以及瞬时和时间平均波入射之间的差异。作为测试案例，组合海岸线模型使用澳大利亚纳拉宾海滩的波浪和海岸线数据进行校准。对每个贡献的单独分析表明，长期趋势主要是海岸漂移贡献，令人惊讶的是，季节性海岸线变化的一部分归因于海岸漂移过程。