PREFACE 



The study herein was authorized by the Headquarters, US Army Corps of 

 Engineers (HQUSACE), Coastal Engineering Area of Civil Works Research and 

 Development. Work was performed under the Characteristics of Long-Period 

 Waves in the Surf Zone, Work Unit 32^30, Shore Protection and Restoration 

 Program at the Coastal Engineering Research Center (CERC), US Army Engineer 

 Waterways Experiment Station (WES). Technical monitors were Messrs. John H. 

 Lockhart, Jr., and John G. Housley, HQUSACE. CERC Program Manager was 

 Dr. C. Linwood Vincent. 



A growing body of knowledge documents the importance of wave energy in 

 the infragravity frequency range (wave periods between 20 and 300 sec). Most 

 important to the coastal engineer are field measurements which indicate that, 

 particularly during storms, infragravity motions can dominate the surf zone 

 energy spectrum and are responsible for the highest run-up and swash motions. 

 Present numerical and physical models do not yet include infragravity wave 

 motions. The purpose of this report is to serve as an introductory text on 

 infragravity wave motions. 



The report was prepared by Dr. Joan Oltman-Shay, Oregon State Univer- 

 sity, and Mr. Kent K. Hathaway, Field Research Facility Group of CERC. The 

 report was prepared under the supervision of Mr. Thomas W. Richardson, Chief, 

 Engineering Development Division, and under the general supervision of 

 Dr. James R. Houston and Mr. Charles C. Calhoun, Jr., Chief and Assistant 

 Chief, CERC, respectively. This report was edited by Ms. Nancy J. Johnson, 

 Information Products Division, Information Technology Laboratory, WES, under 

 the Interpersonnel Agreement Act. 



Acting Commander and Director of WES during preparation of this report 

 was LTC Jack R. Stephens, EN. Technical Director was Dr. Robert W. Whalin. 



