The initial grading of the sand slope in experiment 70X-10 was on 7 

 May 1970, the first run was on 14 May 1970, and the last run was on 30 

 November 1970 after 210 hours. Data collection was completed 2 December 

 1970. Experiment 70X-06 was begun 10 August 1970, was stopped on 5 

 December 1970 after 175 hours, and the data collection completed 15 

 December 1970. The dates are important because the experiments were run 

 in outdoor facilities with water temperature varying with ambient air tem- 

 perature. The major events of each experiment and the cumulative time at 

 the end of each run are summarized in Table 2. 



Table 3 gives the data collection schedule within each run for 1-, 2-, 

 and 5-hour runs. During the first 2 hours when the runs were less than 1 

 hour long, the same data were collected, with the schedule depending on 

 the length of the run. 



3. Scope . 



This report describes and analyzes the reduced data from LEBS experi- 

 ments 70X-06 and 70X-10. The original data are available in an unpublished 

 laboratory memorandum (Chesnutt, 1977) filed in the CERC library (CERTl-LI). 



Wave reflection, profile surveys, sediment-size distribution, breaker 

 characteristics, and water temperature are discussed in the following 

 section. Section III discusses (a) profile development, which examines 

 the interrelation of changes in profile shape, sediment-size distribution, 

 breaker characteristics, and water temperature; and (b) profile reflec- 

 tivity, which examines the interrelation of changes in profile shape, 

 breaker characteristics, and wave reflection. Section IV discusses the 

 results of wave height variability, profile equilibrium, and other labora- 

 tory effects. 



The conclusions and recommendations (Sec. V) are aimed directly at the 

 problems of the laboratory researcher or engineer in charge of a model 

 study. Field engineers should be aware of these conclusions and recommen- 

 dations when discussing and analyzing model studies of their projects. 



The data in this study (particularly the profiles) may have other 

 uses. The researcher can use these data, after consideration of the lab- 

 oratory effects, to analyze short- and long-term changes in profile shape. 

 After an analysis of the scale effects, the field engineer may use these 

 data to determine generalized shoreline recession rates. 



II. RESULTS 



1. Wave Height Variability . 



a. Incident Wave Heights . Wave height measurements from the contin- 

 uous recording of water surface elevation along the center range at station 

 +25 during the first 10 minutes of each experiment are shown in Table 4. 

 The wave heights in the movable-bed tanks varied from 0.09 to 0.38 foot 

 (2.7 to 11.6 centimeters) in experiment 70X-06, and from 0.15 to 0.43 foot 



