1. School of Hydraulic and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, China; 2. Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China
Abstract：A 1DV model (one-dimensional vertical model) is built in this paper to simulate sediment suspension and its effects on contaminant release under the combined action of waves and currents. The ability of the model to describe near bed turbulence characteristics, vertical current structure, suspended sediment transport and contaminant release is validated. The model is used to analyze the dynamic process and temporal/spatial characteristics of contaminant release from suspended sediment under the combined action of waves and currents in different scenarios. Numerical results suggest that vertical distribution of adsorbed contaminants and total contaminants are similar as that of suspended sediments, the periodic oscillation of the wave benthic boundary layer limit the diffusion of the suspended sediment from the bottom to the upper water body, a high concentration layer of sediment and adsorbed contaminants near bed with a steep gradient and small thickness would be formed under the combined action of waves and currents. Analysis results of the evolution of contaminants suggest that vertical distribution of the dissolved contaminants is consistent with adsorbed contaminants during the initial stage and then form a uniform vertical distribution when the contaminant release reached equilibrium. Simulations reveal that flow velocity and wave intensity have different degrees of effects on sediment suspension and contaminant release: water flow has significant impacts on vertical distribution of sediment and contaminant, while wave action plays an important role in the formation of high concentration layer of sediment and contaminant near bed.
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