PREFACE 



This report is published to improve understanding of the occurrence 

 and form of ripples under water waves, since ripples can reduce wave 

 height and affect sand transport. The report summarizes a laboratory 

 study, including prototype offshore conditions, of sand ripple growth in 

 sinusoidal flow. The results will enable the engineer to better predict 

 and interpret equilibrium ripples in the offshore under both laboratory 

 and field conditions. The work was carried out under the coastal pro- 

 cesses program of the U.S. Army Coastal Engineering Research Center 

 (CERC) . 



The report was prepared by Karl E. B. Lofquist, Physicist, Fluid 

 Engineering Division, National Engineering Laboratory, National Bureau 

 of Standards, Gaithersburg, Maryland, under CERC Agreement No. 76-30. 



Dr. R. J. Hallermeier was the CERC monitor for this agreement, under 

 the general supervision of Dr. C. J. Galvin, Jr., Chief, Coastal Processes 

 Branch, Research Division. 



Comments on this publication are invited. 



Published in accordance with Public Law 166, 79th Congress, approved 

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

 7 November 1963. 



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OOHN H. COUSINS 

 Colonel, Corps of Engineers 

 Commander and Director 



