Experimental investigation on irregular wave attenuation under the effects of vegetation with roots, stems and canopies

doi:10.3969/j.issn.1001-909X.2019.04.005

Abstract

Abstract: Based on the theoretical analysis, wave flume experiments were carried out employing vegetation models with quantifiable root, stem and canopy. The attenuation characteristics of irregular wave height within the vegetation filed was investigated by a combination of water depth, incident wave height and vegetation distribution density. Variation of wave spectra associated with vegetation was studied using FFT. The results show that the vegetation models in this experiment have good wave-absorbing effect, but the boundary effect of vegetation wave attenuation is rare. The variation of irregular wave height along the flora is inconsistent with Mendez's theoretical curve most of the time. At the same time, there is no fixed variation of wave energy loss within different sections of the vegetation filed. In addition, the attenuation of wave energy is concentrated at the peak frequency, and increasing incident wave height result in a bigger difference between spectra values of transmitted wave and incident wave at peak frequency, while spectra of both transmitted wave and incident wave show similar bands. This study can provide a theoretical basis for using coastal vegetation to reduce shoreline erosion by surface waves.

Key words: irregular wave, vegetation, wave height attenuation, FFT

CLC Number:

P731.22

CHEN Jie, GONG Shang-peng, GUAN Zhi-xin, ZHANG Zhu, XIE zhen-dong, LEI Jia-xin, PENG Hao. Experimental investigation on irregular wave attenuation under the effects of vegetation with roots, stems and canopies[J]. Journal of Marine Sciences, 2019, 37(4): 48-59.

References

[1] ZHANG Ke-qi, DOUGLAS B, LETHERMAN S. Global warming and coastal erosion[J]. Climatic Change, 2004, 64(1/2): 41-58.
[2] CHEN Jie, GUAN Zhe, JIANG Chang-bo, et al. Study of sediment transport by tsunami waves:Ⅴ: influence of mangrove[J]. Advances in Water Science, 2016, 27(2): 206-213.
陈杰, 管喆, 蒋昌波. 海啸波作用下泥沙运动——Ⅴ.红树林影响下的岸滩变化[J]. 水科学进展, 2016, 27(2):206-213.
[3] CHEN Jie, HE Fei, JIANG Chang-bo, et al. Advances in laboratory experiment, theoretical analysis of mechanism of wave attenuation by vegetation[J]. Advances in Water Science, 2018, 29(3): 439-451.
陈杰, 何飞, 蒋昌波, 等. 植物消波机制的实验与理论解析研究进展[J].水科学进展,2018, 29(3):439-451.
[4] HE Fei, CHEN Jie, JIANG Chang-bo, et al. Effects of wave nonlinearity on wave attenuation by seagrass[J]. Haiyang Xuebao, 2018, 40(5): 24-36.
何飞, 陈杰, 蒋昌波, 等. 波浪非线性对海草消波特性的影响[J]. 海洋学报,2018, 40(5):24-36.
[5] HE Fei, CHEN Jie, JIANG Chang-bo, et al. Experimental study on characteristics of solitary wave height attenuation under effects of a vegetation belt [J]. Advances in Science and Technology of Water Resources, 2018, 38(1): 75-82.
何飞, 陈杰, 蒋昌波,等. 植物带影响下孤立波沿程波高衰减特性试验[J]. 水利水电科技进展,2018, 38(1):75-82.
[6] HE Fei, CHEN Jie, JIANG Chang-bo, et al. Experimental investigation on the characteristics of regular wave height attenuation in vegetation field[J]. Advances in Marine Science, 2018, 36(1): 146-158.
何飞,陈杰,蒋昌波,等. 规则波作用下植物带波高衰减特性实验研究[J]. 海洋科学进展, 2018, 36(1): 146-158.
[7] CHEN Jie, ZHAO Jing, JIANG Chang-bo, et al. Laboratory investigation on the effects of emergent rigid vegetation on the regular wave transformation[J]. Marine Science Bulletin, 2017, 36(2): 222-229.
陈杰, 赵静, 蒋昌波,等. 非淹没刚性植物对规则波传播变形影响实验研究[J]. 海洋通报,2017, 36(2):222-229.
[8] DALRYMPLE R A, KIRBY J T, HWANG P A. Wave diffraction due to areas of energy dissipation[J]. Journal of Waterway Port Coastal & Ocean Engineering, 1984, 110(1): 142-150.
[9] KOBAYASHI N, RAICHLE A W, ASANO T. Wave attenuation by vegetation[J]. Journal of Waterway Port Coastal & Ocean Engineering, 1993, 119(1):30-48.
[10] JOHN B M, SHIRLAL K G, RAO S. Effect of artificial vegetation on wave attenuation-An experimental investigation[J]. Procedia Engineering, 2015, 116(1): 600-606.
[11] WU Wei-cheng, COX D T. Effects of wave steepness and relative water depth on wave attenuation by emergent vegetation[J]. Estuarine Coastal & Shelf Science, 2015, 164: 443-450.
[12] JIANG Chang-bo, WANG Rui-xue, CHEN Jie, et al. Laboratory investigation on solitary wave transformation through the emergent neritic vegetation[J]. Journal of Changsha University of Science and Technology (Natural Science), 2012, 9(2): 51-56.
蒋昌波, 王瑞雪, 陈杰, 等. 非淹没刚性植物对孤立波传播变形影响实验[J]. 长沙理工大学学报(自然科学版), 2012, 9(2): 51-56.
[13] PENG Hao, CHEN Jie, JIANG Chang-bo, et al. Experimental investigation on tsunami wave attenuation under the effect of rigid vegetation distribution[J]. Oceanologia et Limnologia Sinica, 2018, 49(6): 1 159-1 168.
彭浩,陈杰,蒋昌波,等. 刚性植物分布方式对海啸波消减影响实验研究[J]. 海洋与湖沼,2018, 49(6):1 159-1 168.
[14] TANG Jun, CAUSON D, MINGHAM C, et al. Numerical study of vegetation damping effects on solitary wave run-up using the nonlinear shallow water equations[J]. Coastal Engineering, 2013, 75(5): 21-28.
[15] MAZA M, LARA J L, LOSADA I J. Tsunami wave interaction with mangrove forests: A 3-D numerical approach[J]. Coastal Engineering, 2015, 98: 33-54.
[16] MENDEZ F J, LOSADA I J. An empirical model to estimate the propagation of random breaking and nonbreaking waves over vegetation fields[J]. Coastal Engineering, 2004, 51(2): 103-118.
[17] HE Fei, CHEN Jie, JIANG Chang-bo, et al. Experimental investigation on wave attenuation under the effects of rigid vegetation with root, stem and crown[J]. Chinses Journal of Hydrodynamics (Seri A), 2017, 32(6): 770-778.
何飞, 陈杰, 蒋昌波, 等. 考虑根茎叶影响的刚性植物消浪特性实验研究[J]. 水动力学研究与进展(A辑),2017, 32(6):770-778.
[18] CHEN Jie, HE Fei, JIANG Chang-bo, et al. Experimental investigation on drag coefficient of rigid vegetation influenced by regular waves[J]. Journal of Hydraulic Engineering, 2017, 48(7): 846-857.
陈杰,何飞,蒋昌波,等. 规则波作用下刚性植物拖曳力系数实验研究[J]. 水利学报,2017, 48(7):846-857.
[19] HE Fei, CHEN Jie, JIANG Chang-bo, et al. Experimental investigation on tsunami wave attenuation under the effects of coastal vegetation with root, stem and crown[J]. Journal of Tropical Oceanography, 2017, 36(5): 9-15.
何飞,陈杰,蒋昌波,等. 考虑根茎叶的近岸植物对海啸波消减实验研究[J]. 热带海洋学报,2017, 36(5):9-15.
[20] GODA Y, SUZUKI Y. Estimation of incident and reflected waves in random wave experiments[C]// International Conference on Coastal Engineering, 1976: 828-845.
[21] SÁNCHEZ-GONZÁLEZ J F, SÁNCHEZ-ROJAS V, MEMOS C D. Wave attenuation due to posidonia oceanica meadows[J]. Journal of Hydraulic Research, 2011, 49(4): 503-514.
[22] KIT L W. Wave attenuation function of mangroves along Singapore's northern coast[D]. Singapore: National University of Singapore, 2016.
[23] MAZDA Y, WOLANSKI E, KING B, et al. Drag force due to vegetation in mangrove swamps[J]. Mangroves & Salt Marshes, 1997, 1(3): 193-199.
[24] DEKKER F. Hydrodynamics and morphodynamics in and around mangrove forests[D]. Enschede: University of Twente, 2006.
[25] BURGER B. Wave attenuation in mangrove forests[J]. Delft: Technology University of Delft, 2005.
[26] JTJ/T 234—2001 Wave model test regulation[S]. Beijing: China Communications Press, 2001.
JTJ/T 234—2001 波浪模型试验规程[S]. 北京:人民交通出版社, 2001.