This paper deals with the prediction of wave kinematics in the nearshore and coastal zones, where bottom variations strongly affect wave propagation and characteristics. We consider shoaling and breaking wave conditions, through detailed LDV measurements of wave kinematics over the water column in a wave flume. This experimental data-base serves to evaluate and compare several numerical prediction methods, including Flat Bottom Theories (FBT), Sloping Bottom Methods (SBM) and Transfer Function Methods (TFM). It is shown that advanced TFM give the best predictions for wave kinematics, provided that the local free surface elevation signal is available. Particular SBM may also produce reliable prediction for the case of plane slope from a limited number of wave parameters, whereas FBT should not be used in the coastal zone as they are not able to model the shape nor the asymmetry of the velocity profiles.
The knowledge and prediction of wave kinematics is of great importance for many applications in ocean and coastal engineering (design of marine structures, coastal sediment transport, etc.). For the case of near bottom conditions in shallow water, we have already compared experimental measurements of wave kinematics with predictions from various numerical methods (Chevalier, 2000; Benoit et al., 2002; Chevalier et al., 2003). This was done in the context of a study about wave loads on a pipeline in the coastal zone. For the case of vertical and/or surface-piercing structures, two other items should be addressed:
the vertical dependence of the horizontal velocity,
the precise determination of vertical velocities, which are clearly higher than close to the bottom.
These are two points of this study, where measured kinematics over vertical profiles across the coastal zone are compared with predictions from various models presented in the next section.