PREFACE 



Ten experiments were conducted at the Coastal Engineering Research. 

 Center (CERC) from 197Q to 1972 as part of an investigation of the Labora- 

 tory Effects in Beach Studies (LEBS) , to relate wave height variability 

 to wave reflection from a movable-bed profile in a wave tank. The inves- 

 tigation also identified the effects of other laboratory constraints. 

 The work was carried out under the CERC coastal processes program. 



This report (Vol. II), the second of a series of eight volumes, 

 analyzes two movable-bed experiments which show that wave height varia- 

 bility depends on a complex relationship between profile changes and wave 

 reflection. The experiments suggest that tank width and length, and water 

 temperature affect laboratory profile development and that under common 

 laboratory conditions the profiles approach equilibrium more slowly than 

 normally assumed. This study is aimed directly at the problems of the 

 laboratory researcher or engineer in charge of a model study; ultimately, 

 the results will be of use to field engineers in the analysis of model 

 studies. 



Volume 1 of this series documents the procedures used in the 10 

 movable-bed laboratory experiments, and also serves as a guide for con- 

 ducting realistic coastal engineering laboratory studies. Volumes II to 

 VII are data reports for the other experiments; Volume VIII is a final 

 analysis report. 



This report was prepared by Charles B. Chesnutt, principal investiga- 

 tor during the data analysis and report preparation phases of the work, 

 and Robert P. Stafford, senior technician in charge of the two experiments. 

 Dr. C.J. Galvin, Jr., Chief, Coastal Processes Branch, was the principal 

 investigator during the planning and conduct of these two experiments 

 and the early stages of the data reduction. 



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. 



/V ^C^fc-w. >«. »■>.■'«- 



JOHN H. COUSINS 



Colonel, Corps of Engineers 



Commander and Director 



