Salt marshes are dynamic systems able to laterally expand, contract, and vertically accrete in response to sea level rise. Here, we present the grand challenges that need to be addressed to fully characterize marsh morphodynamics. The review focuses on physical processes and quantitative models. Without predictive models, it is impossible to determine the future marsh evolution under accelerated sea level rise. In these models, one of the challenges is to resolve both horizontal and vertical dynamics within the same framework. Vertically, the marsh has to accumulate enough material to contrast rising water levels. Horizontally, marsh erosion at the ocean side must be compensated by landward expansion in forests, lawns, and agricultural fields. The dynamics of the marsh‐upland boundary are still not fully understood and will require more research in the upcoming years. The complexity of marsh vegetation is seldom captured in predictive models of marsh evolution. More research is needed to understand the effects of each species or species assemblages on hydrodynamics and sediment transport. Here, we further advocate that a sediment budget resolving all sediment fluxes in a marsh complex is the most important metric of marsh resilience. Characterization of these fluxes will enable to connect salt marshes to other landforms and to unravel feedbacks controlling the evolution of the entire coastal system. Current models of marsh evolution rely on sparse data sets collected at few locations. Novel remote sensing techniques will provide high‐resolution spatial data that will inform a new generation of computer models.

中文翻译：

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海平面上升时期的盐沼动态

盐沼是动态系统，能够响应海平面上升而横向扩展，收缩和垂直增生。在这里，我们提出了要全面表征沼泽形态动力学所需要解决的巨大挑战。审查侧重于物理过程和定量模型。没有预测模型，就不可能确定加速海平面上升下的未来沼泽发展。在这些模型中，挑战之一是在同一框架内解决水平和垂直动力学问题。在垂直方向上，沼泽必须积累足够的物质来对比不断上升的水位。在水平方向上，必须通过在森林，草坪和农田中向陆地的扩张来补偿海洋一侧的沼泽侵蚀。沼泽-高地边界的动力学仍然没有被完全理解，在未来的几年中将需要更多的研究。沼泽植被的预测模型很少涉及到沼泽植被的复杂性。需要更多的研究来了解每种物种或物种组合对流体动力学和沉积物迁移的影响。在这里，我们进一步主张，解决沼泽综合体中所有沉积物通量的沉积物预算是沼泽抗灾力的最重要指标。这些通量的特征将使盐沼能够与其他地貌联系起来，并能够揭示控制整个沿海系统演化的反馈信息。当前的沼泽演化模型依赖于在几个位置收集的稀疏数据集。