REPORT DOCUMENTATION PAGE 



Form Approved 

 OMB No. 0704-0188 



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1 . AGENCY USE ONLY (Leave blank) 



REPORT DATE 



September 1998 



3. REPORT TYPE AND DATES COVERED 



Final report 



4. TITLE AND SUBTITLE 



Infragravity Waves in the Nearshore Zone 



6. AUTHOR(S) 



Kent K. Hathaway, Joan Oltman-Shay, Peter Howd, Rob A. Holman 



5. FUNDING NUMBERS 



7. PERFORMING ORGANIZATION NAME(S) AND ADDRESSES) 



See reverse. 



8. PERFORMING ORGANIZATION 

 REPORT NUMBER 



Technical Report CHL-98-30 



9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESSES) 



U.S. Army Corps of Engineers 

 Washington, DC 20314-1000 



10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 



11. SUPPLEMENTARY NOTES 



Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. 



12a DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution is unlimited. 



12b. DISTRIBUTION CODE 



1 3. ABSTRACT (Maximum 200 words) 



This report summarizes the present state of knowledge on infragravity wave motions (nominally 0.003 to 0.05 Hz). 

 Theoretical and observational studies are presented. Most of the studies discussed herein have been published else- 

 where, however a few studies discussed in chapter 4 are presented for the first time in this report. Measurements of 

 nearshore waves and currents have shown that a significant amount of the total energy can be contained in the infra- 

 gravity band, and on highly dissipative beaches the infragravity wave variance often dominates over energy in the inci- 

 dent wave band(0.05 to 0.3 Hz). An 8-month data set of infragravity variance measured at 8-m depth at the shoreline 

 (runup) was compared with incident wave variance. Analysis of the 8-m-depth data showed that high mode edge 

 waves account for about 50 percent of the total infragravity variance, and as high as 80 percent at times. Significant 

 edge wave heights greater than 20 cm were observed at the 8-m depth. Infragravity wave variance was shown to have 

 a higher correlation with swell variance (C = 0.95) than with sea variance (C = 0.61). This report was motivated, in 

 part, by the need to determine the significance of infragravity waves on coastal erosion and structure damage and by 

 the desire to improve coastal engineering solutions to problems associated with nearshore processes. 



14. SUBJECT TERMS 







Infragravity waves 



Leaky wave 



Runup 



Edge waves 



Shear waves 



Swash 



Bound waves 



Beach morphology 



Sand bars 



15. NUMBER OF PAGES 



89 



16. PRICE CODE 



17. SECURITY CLASSIFICATION 

 OF REPORT 



UNCLASSIFIED 



18. SECURITY CLASSIFICATION 

 OF THIS PAGE 



UNCLASSIFIED 



19. SECURITY CLASSIFICATION 

 OF ABSTRACT 



20. LIMITATION OF ABSTRACT 



NSN 7540-01-280-5500 



Standard Form 298 (Rev. 2-89) 



Prescribed by ANSI Std. 239-16 

 298-102 



