Seasonal variations in drag coefficient of salt marsh vegetation

• Published in: Coastal engineering (Amsterdam) 2024-10, Vol.193, p.104575, Article 104575
• Main Authors: Li, Changyang, Peng, Zhong, Zhao, Ying, Fang, Dan, Chen, Xianjin, Xu, Fan, Wang, Xianye
• Format: Article
• Language: English
• Subjects: Drag coefficient; Salt marsh vegetation; Seasonal variation; Wave attenuation; Wave nonlinearity
• ISSN: 0378-3839
• DOI: 10.1016/j.coastaleng.2024.104575

Understanding the seasonal variations of vegetation drag coefficients is crucial for improving wave attenuation predictions and adapting to climate impacts. This study explores the seasonal changes in drag coefficients within salt marsh vegetation, using data from a year-long series of field measurements at the Chongming Dongtan Wetland. It uncovers the complex seasonal variations of drag coefficients. Results demonstrate that incorporating a nonlinear equation for characteristic flow velocity and effective vegetation length significantly improves the precision of drag coefficient predictions, ensuring a closer match with field observations. Furthermore, it introduces a refined drag coefficient formula that incorporates adjustments for vegetation stiffness and relative submergence, offering a more accurate representation of the seasonal variability in drag forces exerted by salt marsh vegetation. This enhanced formula is crucial for accurately assessing vegetation's role in wave attenuation, providing critical insights for the design and implementation of coastal defense and wetland conservation initiatives. •Significant seasonal fluctuations are evident in the drag coefficient, vegetation stiffness, and relative submergence.•Nonlinear characteristic velocity within the stem Reynolds number is influenced by seasonal variations in vegetation stiffness and relative submergence.•Development of a new formula that adjusts for the seasonal changes in drag coefficient within salt marsh vegetation.