Sediment transport by kinematic waves

摘要

In shallow water, the dynamics of the surface gravitational waves with a period of several hours can be described using a gradient-viscous or kinematics approximation. To estimate the sediment transport under the impact of various dynamical factors, two approaches are the most widely applied, based on: (1) applying the vertically averaged current velocity, and (2) using the near-bottom tangential stress as the main parameter. The calculations show that a compensatory current directed seawards is generated on the rising water level within the near-bottom layer. The transport of sediments is directed in accordance with the direction of the compensatory currents, i.e. seawards in the sea rise periods and to the shore in the periods of descending water. The absolute value of the specific discharge of sediments transported by the kinematic waves within the littoral zone studied depends mainly on the rate of change of the free surface, partialderiv ξ/partial deriv t. As this takes place, the role of the kinematic waves in the sediment transport may be comparable with the role of the wind waves.