Abstract：The numerical model for wave propagation in vegetation water was developed based on fully nonlinear Boussinesq equation in which the drag force due to vegetation was added. The model was verified by comparing between the numerical and experimental results for wave propagation in vegetation waters. The numerical results are in line with flume experiments. Then the model was used to test waves propagating through a finite patch of vegetation at the bank slope. An analysis is conducted to understand shoaling, breaking and wave-induced current by aquatic vegetation. It is found that the wave height in the vegetated zone is attenuated more rapidly than in the adjacent unvegetated region, which is induced by the damping effects of the vegetation. Compared with the vegetation away from the shoreline, the vegetation affects more on attenuation in the surf zone, no secondary crushing occuring. And wave phase speed and wave length of the broken wave are also decreased in the vegetated region compared to the unvegetated region, which leads to refraction effects bending wavecrests towards the patch in the exterior region. When vegetation is located in inthe surf zone, the wave setup is significantly reduced. In the outer part of the vegetation patch(close to the breaker line), the wave setup is relatively larger. The vegetation has a significant effect on the nearshore circulation, and the nearshore circulation and the large-scale vortex appear on the edge of the vegetation. The distribution of the offshore flow in shore is uniform, the flow velocity is small and the distribution range is relatively large. The farther the vegetation area is from the shoreline, the larger the vortex scale is, and the more intense the offshore flow is.
YANG Zhi-yong,TANG Jun. Numerical study for conical wave propagation in slope vegetation waters[J]. Marine Environmental Science, 2018, 37(5): 640-646.
HASHIM A M,CATHERINE S M P.A laboratory study on wave reduction by mangrove forests[J].APCBEE Procedia,2013,5:27-32.
[3]
KNUTSON PL,BROCHU R A,SEELING WN,et al.Wave dampening in Spartinaalternifloramarshes[J].1982,2(1):87-104.
[4]
ZABLOUDIL K,REITZEL J,SCHROETER S,et al.Sonar mapping of giant kelp density and distribution[C]//Coastal Zone 91.Reston,Virginia:ASCE,1991:391-406.
[5]
ELWANY M H S,O'REILLY W C,GUZA R T,et al.Effects of southern California kelp beds on waves[J].Journal of Waterway,Port,Coastal,and Ocean Engineering,1995,121(2):143-150.
[6]
ASANO T,TSUTSUI S,SAKAI T.Wave damping characteristics due to seaweed[C]//Proceedings of 25th Coastal Engineering Conference in Japan.Matsuyama:[s.n.],1988:138-142.
[7]
AUGUSTIN L N.Laboratory experiments and numerical modeling of wave attenuation through artificial vegetation[D].Texas A&M University,2007.
[8]
LOVAS S M,TORUM A.Effect of the kelp laminariahyperborea upon sand dune erosion and water particle velocities[J].Coastal Engineering,2001,44(1):37-63.
HUANG Z H,YAO Y,SIM S Y,et al.Interaction of solitary waves with emergent,rigid vegetation[J].Ocean Engineering.2011,38(10):1080-1088.
[12]
AUGUSTIN L N,IRISH J L,LYNETT P.Laboratory and numerical studies of wave damping by emergent and near-emergent wetland vegetation[J].Coastal Engineering,2009,56(3):332-340.
LYNETT P J,WU T R,LIU L F.Modeling wave run-up with depth-integrated equations[J].Coastal Engineering,2002,46(2):89-107.
[17]
NWOGU O.Alternative form of boussinesqequations for nearshore wave propagation[J].American Society of Civil Engineers,1993,119(6):618-638.
[18]
WHITFORD D J,THORNTON E B.Bed shear stress coefficients for longshore currents over a barred profile[J].Coastal Engineering,1996,27(3/4):243-262.
[19]
KOBAYASHI N,KARJADI E A,JOHNSON B D.Dispersion effects on longshore currents in surf zones[J].Journal of Waterway,Port,Coastal,and Ocean Engineering,1997,123(5):240-248.
[20]
KENNEDY A B,CHEN Q,KIRBY J T,et al.Boussinesq modeling of wave transformation,breaking,and runup.I:1D[J].Journal Of Waterway,Port,Coastal,and Ocean Engineering,2000,126(1):39-47.
[21]
KOTHYARI U C,HASHIMOTO H,HAYASHI K.Effect of tall vegetation on sediment transport by channel flows[J].Journal of Hydraulic Research,2009,47(6):700-710.
[22]
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.
[23]
MA G F,KIRBY J T,SU S F,et al.Numerical study of turbulence and wave damping induced by vegetation canopies[J].Coastal Engineering,2013,80:68-78.
[24]
DEAN R G,BENDER C J.Static wave setup with emphasis on damping effects by vegetation and bottom friction[J].Coastal Engineering,2006,53(2/3):149-156.
