The concepts of energy flux and group velocity for nonlinear periodic gravity waves are discussed. The average energy flux, average energy per wavelength and group velocity are calculated for irrotational periodic gravity waves at a third order of approximation. Then the principle of conservation of transmitted energy between wave orthogonals is applied to the same order of approximation for determining the variation of wave height in decreasing depth. The results are presented as nomographs. It is seen that the shoaling coefficient needs to be expressed at least at a third order of approximation to account for experimental results. The second part of the report is the summary of a literature survey which has been carried out on the problem of littoral processes. It is now possible to make further refinements to the material presented in progress report SN 134-1 on waves arriving at an angle with the shoreline. Also the way is paved for applying the theoretical results, already obtained in SN 134, to the problem of littoral processes.