PREFACE 



This report presents some ways in which a horizontal current influences 

 surface gravity waves and their measurement. Relatively simple hand- 

 calculation methods are described which provide ways to estimate how much 

 currents affect the wavelength and measured height of waves. These methods 

 are the initial results of a research effort designed to furnish practical 

 guidance on how to account for the effects of currents on waves. Such guid- 

 ance fills an information gap in the Shore Protection Manual ( SPM) . The work 

 was carried out under the waves on currents program of the U.S. Army Coastal 

 Engineering Research Center (CERC). 



The report was prepared by Dr. Barry E. Herchenroder, Oceanographer, under 

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

 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 



