The effects of plant structure and flow properties on the physical response of coastal dune plants to wind and wave run-up
The effects of plant structure and flow properties on the physical response of coastal dune plants to wind and wave run-up
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DOI：
10.1016/j.ecss.2021.107556
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发表时间：
2021-08-25
影响因子：
2.8
通讯作者：
Smith, Jeremy
中科院分区：
文献类型：
--
作者：
Innocenti, Rachel A.;Feagin, Rusty A.;Smith, Jeremy
植被是海岸沙丘的重要特征，通常被用来稳定恢复的沙丘，提供海岸保护。尽管在种植和管理方面投入了大量资金，但人们对风浪对植被的影响知之甚少。本研究的目的是1)研究海岸沙丘植被在风浪上升过程中所经历的升力和阻力力矩，2)将其与流动特性和植物形态联系起来。在实验室的风浪条件下，对苦参、羊肠菌、沙蚕和海螺进行了研究。测量了流体流速、上升深度、雷诺数和植物的生物物理特性。利用一种新型传感器记录植物的升力和阻力响应，该传感器旨在解决实际植被在不同条件下的灵活性和形态引起的复杂性。采用回归分析方法描述了植物响应与植物结构和流动特性之间的关系。实验表明，随着时间的推移，风诱导植物产生恒定的升力和阻力力矩，而爬升诱导植物的反应则是时间依赖性的。株高（R-2 = 0.64, p < 0.001）和叶片数（R-2 = 0.67, p = 0.30）分别是风阻试验和爬升试验中最重要的预测因子。来自风的植物阻力系数（5.0 × 10（-4）至3.6 × 10(-2)）和爬升（2.7 × 10（-3）至1.7）与气流湍流呈负相关，表明沿海沙丘植物可能对诱导力具有生物物理适应性，例如流线型倾向。特别是，我们的数据表明，高而薄的沙丘草最适合在沙丘顶部和前缘使用，以减少风能，而低矮的灌木植物最适合在沙丘后滩或沙丘脚趾使用，以减少上升能量。我们的研究为沙丘植被中断水流的能力提供了有价值的信息，这样建模者和管理者就能更好地了解如何最好地保护海岸线。
Vegetation is an important feature of coastal dunes and is often managed to stabilize restored dunes and provide coastal protection. Despite a high investment in planting and management efforts, little is known about how vegetation is affected by wind and wave run-up. The objectives of this study were to 1) investigate the lift forces and drag moments experienced by coastal dune vegetation from wind and wave run-up and 2) relate them to flow properties and plant morphology. Panicum amarum, Ammophila breviligulata, A. arenaria and Cakile maritima were subjected to laboratory wind and wave run-up conditions. Measurements were taken of fluid velocity, runup depth, Reynolds number, and plant biophysical properties. The plant lift and drag responses were recorded with the use of a novel sensor designed to address the complexities induced by the flexibility and morphology of real vegetation under varying conditions. Regression analysis was used to describe the relationships between plant response and plant structure and flow properties. Experiments showed that wind induced a constant lift force and drag moment on plants over time, whereas run-up induced plant response was time-dependent. Plant height (R-2 = 0.64, p < 0.001) and number of leaves (R-2 = 0.67, p = 0.30) were the most important predictors of drag moment from wind and run-up experiments, respectively. Plant drag coefficients from wind (5.0 x 10(-4) to 3.6 x 10(-2)) and run-up (2.7 x 10(-3) to 1.7) were negatively correlated with flow turbulence, indicating that coastal dune plants likely have biophysical adaptations to the induced forces, such as a propensity for streamlining. In particular, our data suggests that tall and thin dune grasses are best adapted and used on the dune crest and fronts to mitigate wind energy, while low shrubby plants are best used on the backbeach or dune toe to reduce run-up energy. Our study provides valuable information on the ability of dune vegetation to interrupt flow, such that modelers and managers can better understand how to best protect coastlines.