Department of Earth and Environment, Boston University, Boston, Massachusetts, USA.
The Water Institute of the Gulf, New Orleans, Louisiana, USA.
Sci Rep. 2023 Feb 18;13(1):2884. doi: 10.1038/s41598-023-30042-y.
Salt marshes are threatened by rising sea levels and human activities, and a major mechanism of marsh loss is edge retreat or erosion. To understand and predict loss in these valuable ecosystems, studies have related erosion to marsh hydrodynamics and wave characteristics such as wave power. Across global studies, erosion is reported to be largely linearly related to wave power, with this relationship having implications for the resilience of marshes to extreme events such as storms. However, there is significant variability in this relationship across marshes because of marsh heterogeneity and the uniqueness of each physical setting. Here, we investigate the results of individual studies throughout the world that report a linear relationship and add a new dataset from the Great Marsh in Massachusetts (USA). We find that most marsh wave power and erosion data are not normally distributed and when these datasets are properly plotted to account for their distributions, the resulting relationships vary from previously published curves. Our Great Marsh data suggest that events from specific wind directions can have an outsized impact on edge erosion due to their larger fetch and wind speeds. We also find that factors other than wave attack such as edge erosion along tidal channels, can have a measurable impact on retreat rates. We show the importance of maintaining statistical assumptions when performing regressions, as well as emphasize the site-specificity of these relationships. Without calibration of a marsh erosion-wave power relationship using robust regressions for each individual marsh, such a relationship is not fully constrained, resulting in unreliable predictions of future marsh resilience and response to climate change.
盐沼受到海平面上升和人类活动的威胁，而沼泽损失的一个主要机制是边缘后退或侵蚀。为了理解和预测这些有价值的生态系统的损失，研究已经将侵蚀与沼泽水动力学和波浪特征（如波浪能）联系起来。在全球范围内的研究中，侵蚀与波浪能之间的关系被报道为大致线性关系，这种关系对沼泽对风暴等极端事件的恢复力有影响。然而，由于沼泽的异质性和每个物理环境的独特性，这种关系在沼泽之间存在很大的可变性。在这里，我们研究了世界各地报告线性关系的个别研究的结果，并添加了来自美国马萨诸塞州大沼泽的数据。我们发现，大多数沼泽波浪能和侵蚀数据不是正态分布的，当这些数据集根据其分布进行正确绘制时，得到的关系与以前发表的曲线不同。我们的大沼泽数据表明，由于特定风向的较大迎水面和风速，来自特定风向的事件可能会对边缘侵蚀产生不成比例的影响。我们还发现，除了波浪攻击之外的因素，如潮汐通道边缘的侵蚀，也会对后退率产生可测量的影响。我们展示了在进行回归时保持统计假设的重要性，并强调了这些关系的特定于地点的性质。如果不对每个单独的沼泽进行稳健回归校准沼泽侵蚀-波浪能关系，那么这种关系就不会受到完全约束，从而导致对未来沼泽恢复力和对气候变化响应的不可靠预测。
