PREFACE 



This report presents state-of-the-art irregular wave prediction techniques 

 developed by Goda (1975a, 1975b) and suggested by Goda, Takayama, and Suzuki 

 (1978) . When this report was prepared, little field data were available for 

 checking the techniques presented. New data are being gathered at the U.S. 

 Army Coastal Engineering Research Center's (CERC) Field Research Facility (FRF) 

 at Duck, North Carolina, and results of comparing the new prediction techniques 

 with this data are expected in early 1981. 



Much of the design information in the Shore Protection Manual (SPM) assumes 

 monochromatic waves; however, input wave conditions for many design analyses 

 are often irregular. This report, which supplements SPM Sections 2.3, 3.85, 

 and 7.12, presents methods developed for open sections of the coast with contin- 

 uously shallowing bottom contours. The major emphasis of the report is on pre- 

 dicting nearshore wave height distributions. The work was carried out under 

 the offshore breakwater for shore stabilization and wave runup and overtopping 

 programs of CERC. 



Goda's methods represent an important increase in the engineering communi- 

 ty's ability to predict waves propagating into shallow water. The method is 

 based on a number of simplifications and empirical adjustments but appears to 

 represent laboratory and limited field data reasonably well. Additional com- 

 parisons of predictions with field data are underway. Meanwhile, prediction 

 results should be carefully evaluated to confirm that the method is not used 

 outside of its range of applicability. 



The report was prepared by William N. Seelig and John P. Ahrens, under the 

 general supervision of Dr. R.M. Sorensen, Chief, Coastal Processes and Struc- 

 tures Branch. 



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. 



TED E. BISHOP 



Colonel, Corps of Engineers 



Commander and Director 



