PREFACE 



The tendency for high waves to group is a phenomenon of considerable 

 interest in the coastal and ocean engineering community. This grouping has 

 special importance in the Corps of Engineers because several high waves in 

 succession can represent a more severe design condition for coastal structures 

 than ungrouped waves. In particular, recent evidence indicates that grouped 

 waves can be more damaging to a rubble-mound structure than ungrouped waves 

 with the same heights. This report deals primarily with relatively simple 

 cases of waves in deep water. However, it is hoped (and expected) that the 

 analysis techniques and results developed in this study will lead to a better 

 understanding of wave grouping characteristics in shallow water. The work, was 

 carried out under the U.S. Army Coastal Engineering Research Center's (CERC) 

 Wave Estimation for Design work, unit, Coastal Flooding and Storm Protection 

 Program, Coastal Engineering Area of Civil Works Research and Development. 



The report was prepared by Dr. Edward F. Thompson, Hydraulic Engineer, 

 under the supervision of Dr. C.L. Vincent, Chief, Coastal Oceanography Branch, 

 and Mr. R.P. Savage, Chief, Research Division. 



The author acknowledges the guidance and encouragement throughout this 

 study provided by Dr. J.E. Feir, Associate Dean of the School of Engineering 

 and Applied Science, George Washington University; Dr. D.L. Harris, formerly 

 wi-th CERC and currently Research Scientist, College of Engineering, Univer- 

 sity of Florida; Dr. R.M. Sorensen, Chief, Coastal Processes and Structures 

 Branch, CERC; and Dr. B.E. Herchenroder, Mathematician-Oceanographer, CERC. 

 Dr. Harris also provided the computer program for multiple regression screen- 

 ing analysis. W. Buckley and M. Davis of the U.S. Navy David W. Taylor Naval 

 Ship Research and Development Center made possible the inclusion of wave data 

 from Hurricane Camille in this study. 



The material included in this report provided the basis for a dissertation 

 submitted to the George Washington University in partial satisfaction of the 

 requirements for the Doctor of Science degree (Thompson, 1981). 



Technical Director of CERC was Dr. Robert W. Whalin, P.E., upon publica- 

 tion of this report. 



Comments on this publication are invited. 



Approved for publication in accordance with Public Law 166, 79th Congress, 

 Approved 31 July 1945, as supplemented by Public Law 172, 88th Congress, 

 approved 7 November 1963. 



iD E. BISHOP 

 Colonel, Corps of Engineers 

 Conmiander and Director 



