Chapter 1 



Introduction and Review 

 of Current Methods 



1.1 Background 



Wave kinematics are involved in most processes that coastal engineers study. 

 Knowledge of fluid velocities and accelerations are necessary for the study of the 

 wave loading of structures through the use of the O'Brien-Morison equation. Knowl- 

 edge of the kinematics near the sea bed are necessary for studies of sediment transport 

 processes. For this reason, it is important that wave measurements be interpreted as 

 accurately as possible. 



Despite the need for good data on the kinematics of waves, it is impractical to 

 measure every parameter of interest. In a given situation, one might need to know the 

 velocities, accelerations, and pressure fluctuations throughout the depth at a given 

 location. While, in the laboratory, it might be possible to measure these quantities 

 at many locations, it would be very expensive, and it is totally impractical in the 

 field. A pragmatic approach is to measure just a few quantities, and to use a wave 

 theory to compute the balance of the parameters. This approach can give a complete 

 description of the kinematics from only a few measurements. Unfortunately, the 

 accuracy of this approach is limited by the accuracy of the adopted theory, as well as 

 the accuracy of the measurements themselves. 



