The two experiments discussed in this study were repeats of the first 

 two experiments with more sand added so that the initial test length 

 (distance from the wave generator to the initial Stillwater level (SWL) 

 intercept) was shortened by 7 feet (2.1 meters) in both tanks, in hopes 

 that the erosion would not reach the back of the tank before the profile 

 attained equilibriiom. 



The two experiments covered in this study have been discussed in part 

 in earlier reports. Chesnutt, et al. (1972) discussed the development of 

 the profiles in four LEBS experiments, including the two in this study. 

 Chesnutt and Galvin (1974) analyzed the relationship between reflection 

 variability and profile development in the same four experiments discussed 

 by Chesnutt, et al . (1972). Chesnutt (1975) analyzed other laboratory 

 effects observed in three LEBS experiments, including one of the two in 

 this volume. 

 2. Experimental Procedures . 



The experimental procedures used in the LEBS experiments are described 

 in Volume I (Stafford and Chesnutt, 1977) which provides the necessary 

 details on the equipment, quality control, data collection, and data 

 reduction for all 10 experiments. 



The data collection and reduction procedures unique to the two experi- 

 ments in this study are documented in the Appendix. The conditions of 

 these two LEBS experiments (71Y-06 and 71Y-10) are summarized in Table 1. 

 The table shows that the initial slope, water depth, wave period, wave 

 fieight, and sand size were the same in both experiments. 



Table 1 



Summary of 



experimental cond 



itions. 



Experiment^ 



Initial test 



length 



(ft) 



Initial 

 slope 



Wave 



period 



(s) 



Generated 



wave height 



(ft) 



71Y-06 

 71Y-10 



93.0 



54.7 



0.10 

 0.10 



1.90 

 1.90 



— ;= — TTS s =: 



0.36 

 0.36 



^Refer to Volume I (Stafford and Chesnutt, 1977) for 

 relation between these experiments and the other eight 

 LEBS experiments. 



NOTE. --The same sediment was used in both experiments; 

 the initial d^Q (by dry sieve analysis) was 0.23 milli- 

 meter. 



Two experimental facilities were used (see Figs. 3 and 4 in Vol. I 

 and Fig. A-1 in the App.). Each facility consisted of two side-by-side 

 wave tanks, one with a 0.10 concrete slope and the other a sand slope. 

 A generator was common to each pair of tanks so that each had identical 

 wave energy input. The operation of the generators is described in 

 Section IV and Appendix B of Volume I. The concrete slope provided a 

 control (a bench-mark value) for the varying reflection measured in the 

 neighboring tank with the movable bed. 



10 



