AUTHOR=Ma Yuxi , Zhu Longhuan , Peng Zhong , Xue Liming , Zhao Wenzhen , Li Tianyou , Lin Shiwei , Bouma Tjeerd J. , Hofland Bas , Dong Chuning , Li Xiuzhen 

TITLE=Wave attenuation by flattened vegetation (Scirpus mariqueter)

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1106070

DOI=10.3389/fmars.2023.1106070

ISSN=2296-7745

ABSTRACT=With the capacity to reduce wave energy and trap sediment, Scirpus mariqueter has become an important native species of annual grass for ecology restoration at the Yangtze Estuary in eastern China. Due to seasonal variances of biophysical characteristics, S. mariqueter usually bends and breaks in winter, resulting in flattened stems that may reduce its wave attenuation capacity. To investigate the effects of vegetation flattening on wave attenuation, a set of flume experiments were conducted for flattened and standing vegetation under different wave conditions. The model vegetation was designed to represent the wilt S. mariqueter collected in winter with dynamic similarity. Results showed that the wave damping coefficient for flattened vegetation (β_F) was 33.6%-72.4% of that for standing vegetation (β_S). Both β_F and β_S increased with wave height but decreased with water depth. A wave attenuation indicator was defined to generate empirical formulas for β_S and β_F as well as their ratio β_F/β_S. The empirical formulas were then applied to modify the existing standing vegetation-based wave attenuation model for flattened vegetation and performed very well. Understanding the wave attenuation of flattened vegetation is essential for the management of ecological restoration and coastal protection.