With large-scale human interventions and climate change unfolding as they are now, coastal changes at decadal timescales are not limited to incremental modifications of systems that are fixed in their general geometry, but often show significant changes in layout that may be catastrophic for populations living in previously safe areas. This poses severe challenges that are difficult to meet for existing models. A new free-form coastline model, ShorelineS, is presented that is able to describe large coastal transformations based on relatively simple principles of alongshore transport gradient driven changes as a result of coastline curvature, including under highly obliquely incident waves, and consideration of splitting and merging of coastlines, and longshore transport disturbance by hard structures. An arbitrary number of coast sections is supported, which can be open or closed and can interact with each other through relatively straightforward merging and splitting mechanisms. Rocky parts or structures may block wave energy and/or longshore sediment transport. These features allow for a rich behavior including shoreline undulations and formation of spits, migrating islands, merging of coastal shapes, salients and tombolos. The main formulations of the (open-source) model, which is freely available at www.shorelines.nl, are presented. Test cases show the capabilities of the flexible, vector-based model approach, while field validation cases for a large-scale sand nourishment (the Sand Engine; 21 million m3) and an accreting groin scheme at Al-Gamil (Egypt) show the model’s capability of computing realistic rates of coastline change as well as a good representation of the shoreline shape for real situations.

中文翻译：

---

复杂沙质海岸演化的月到世纪时间尺度的有效建模

随着大规模人类干预和气候变化的展开，十年时间尺度的沿海变化不仅限于固定在其一般几何结构中的系统的增量修改，而且经常显示布局的重大变化，这可能对居住的人口造成灾难性的影响。在以前安全的区域。这给现有模型带来了难以应对的严峻挑战。提出了一种新的自由形式海岸线模型 ShorelineS，该模型能够基于相对简单的沿海岸运输梯度驱动变化的原理来描述大型海岸变换，这些变化是海岸线曲率的结果，包括在高度倾斜的入射波下，并考虑分裂和海岸线的合并，以及硬结构对沿岸运输的干扰。支持任意数量的海岸段，可以是开放的或封闭的，并且可以通过相对简单的合并和拆分机制相互交互。岩石部分或结构可能会阻碍波浪能和/或沿岸沉积物的输送。这些特征允许丰富的行为，包括海岸线的起伏和形成的唾液、迁移的岛屿、海岸形状的合并、突出部和连环岛。 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 介绍了可在 www.shorelines.nl 上免费获得的（开源）模型的主要公式。测试案例展示了灵活的、基于矢量的模型方法的能力，而大型沙土营养（沙引擎；