Leonardi Nicoletta, Ganju Neil K, Fagherazzi Sergio
Department of Earth and Environment, Boston University, Boston, MA 02215;
US Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA 02543-1598.
Proc Natl Acad Sci U S A. 2016 Jan 5;113(1):64-8. doi: 10.1073/pnas.1510095112. Epub 2015 Dec 22.
Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.
由于土地利用变化、海浪侵蚀和海平面上升，全球范围内都有盐沼流失的记录。目前尚不清楚盐沼对极端风暴的抵抗力如何，以及它们能否在多次事件中幸存而不坍塌。基于在世界各地收集的大量盐沼横向侵蚀速率数据集，我们在此确定了正常和极端天气条件下盐沼边界对波浪作用的一般响应。随着波浪能量增加，盐沼对风浪的响应保持线性，且在波浪能量方面不存在一个临界阈值，超过该阈值盐沼侵蚀会急剧加速。我们将盐沼侵蚀的一般公式应用于美国受飓风影响的八个盐沼地点的历史波浪气候。基于对二十年数据的分析，我们发现强烈风暴和飓风对长期盐沼侵蚀速率的贡献不到1%。相比之下，重现期为2.5个月的中度风暴是导致盐沼退化最严重的因素。因此，盐沼似乎更容易受到平均波浪能量变化的影响，而不是极端情况的变化。沿海管理者在恢复项目和风险管理计划中应考虑盐沼对强烈风暴的固有抵抗力及其在中度事件期间可预测的侵蚀速率。
