On energy transport and group velocity of water waves

The major difference between the two concepts,"transport" and "propagation",of wave energy is expounded in both mathematical expression and basic idea,and the mechanism of energy transport and the meaning of group velocity for water waves are discussed in this paper.A number of important conclusions are given from the present discussion,which are favourable to clarifying some confusion or obscurity as such concepts as energy transport,propagation and group velocity are used in the study of water wave theory and its applications.