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 variability 

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

 vestigation 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 pro- 

 gram. 



This report (Vol. IV), the fourth in a series of eight volumes on the 

 LEBS experiments, analyzes a movable-bed experiment run under nearly the 

 same conditions as one of the experiments described in Volume III except 

 that the initial profile slope was 0.05 rather than 0.10. As in Volume 

 III, this experiment showed a slower approach to profile equilibrium than 

 normally anticipated in movable-bed experiments. A different profile 

 shape developed as a result of the flatter initial slope. This experi- 

 ment provided further verification of the great effect of profile change 

 on reflection coefficient, and thus on wave height variability. 



Volume I of this series 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 report was prepared by Charles B. Chesnutt, principal investi- 

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

 experiments. Dr. C.J. Calvin, Jr., 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 



