ABSTRACT
Liu, H.; Deng, J., and Wu, J., 2023. Benthic turbulence affected by various wave conditions in the surf zone. Journal of Coastal Research, 39(6), 1082–1093. Charlotte (North Carolina), ISSN 0749-0208.
To understand turbulence and associated sediment transport in the surf zone, it is of crucial importance to explore the effect of wind waves consisting of non-breaking (low) and breaking (moderate) waves. A bottom-mounted instrumental tripod was deployed on a dissipative beach in the surf zone in the south China coast to examine the relative importance of wave-induced turbulence and bed-induced turbulence in the different hydrodynamic conditions. The data were collected in 0.5–3 m water depth from 20–29 July 2016. During the survey, a tropical storm attacked the nearby coast from 26–27 July. The Synchrosqueezed Wavelet Transform method was used to decompose the wave and turbulent data. The results show that the bed-generated turbulence dominated with weak wind waves during neap tide. The Reynolds shear stresses and turbulent kinetic energy was almost vertically uniform in this period. On the contrary, the degree of turbulence anisotropy became weak and various turbulence properties or scaling (e.g., Reynolds shear stresses, turbulent kinetic energy, dissipation rate, Froude-scaled turbulence) enhanced significantly with moderate waves during spring tide and storm period. The turbulent properties increased in magnitude away from the bed beneath waves breaking. The observations suggest that breaking waves are the dominant source of turbulence under strong onshore winds, which are significant and may dominate over bottom boundary layer process in the surf zone.
