PREFACE 



Ten experiments were conducted at the Coastal Engineering Research 

 Center (CERC) from 1970 to 1972 as part of an investigation of the Lab- 

 oratory Effects in Beach Studies (LEBS), to relate wave height varia- 

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

 investigation also identified the effects of other laboratory constraints. 

 The LEBS project is directed toward the solution of problems facing 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. The work was carried out under the CERC coastal processes 

 program. 



This report (Vol. Ill) is the third in a series of eight volumes on 

 the LEBS experiments. Volume I describes the procedures used in the 

 10 LEBS experiments, and also serves as a guide for conducting realistic 

 coastal engineering laboratory studies; Volumes II to VII are data reports 

 covering all experiments; Volume VIII summarizes the LEBS experiments 

 detailed in the earlier volumes. 



This volume analyzes two movable-bed experiments run under nearly the 

 same conditions as the experiments described in Volume II. As in Volume 

 II, these repeat experiments show a slower approach to equilibrium profile 

 than normally anticipated in movable-bed experiments, and a probable re- 

 lation between tank width and profile development. These experiments 

 indicate an even greater effect of profile change on reflection coeffi- 

 cient, and thus on wave height variability. However, the effect of 

 temperature on the profile development indicated in Volume II is not 

 supported by these experiments. 



This report was prepared by Charles B. Chesnutt, principal investigator, 

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

 Dr. C.H. Everts, now Chief, Geotechnical Engineering Branch, supervised 

 3 months of the testing reported in this volume. Dr. C.J. Calvin, Chief, 

 Coastal Processes Branch, provided general supervision. 



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. 



/JOHN H. COUSINS 

 Colonel, Corps of Engineers 

 Commander and Director 



