2. Experimental Procedures . 



The experimental procedures used in the LEBS experiments are described 

 in Volume 1 (Stafford and Chesnutt, 1977) which provides the necessary 

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

 tion for all 10 experiments. An appendix to this study documents the data 

 collection and reduction procedures unique to these two experiments. The 

 conditions of the two LEBS experiments (70X-06 and 70X-10) are summarized 

 in Table 1. The table shows that the initial slope, water depth, wave 

 period, wave height, and sand size were the same in the two experiments. 



Table 



1. Summary of 



experimental conditions. 



Experiment^ 



Initial test 



length 



(ft) 



Initial 

 slope 



Wave 



period 



(s) 



Generated 



wave height 



(ft) 



70X-06 

 70X-10 



100.0 

 61.7 



0.10 

 0.10 



1.90 

 1.90 



0.36 

 0.36 



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

 relation between these experiments and the other eight 

 LEBS experiments. 



NOTE. --Constants for the two experiments: dso (by dry 

 sieve analysis) of quartz sand = 0.23 millimeter; 

 water depth = 2.33 feet; wave energy flux = 5.8 foot- 

 pounds per second-foot. 



Two experimental facilities were used (see Figs. 3, 4, and 5 of Vol. 

 I). Each facility consisted of two side-by-side wave tanks, one with a 

 0.10 concrete slope and the other a sand slope (also discussed in Sec. 

 II, 2). The generator at the other end was common to both of the tanks 

 so that each had identical wave energy input. The operation of the gen- 

 erators is described in Section IV and Appendix B of Volume I. The con- 

 crete slope provided a control (a bench-mark value) for the varying 

 reflection measured in the neighboring tank with the movable bed. 



The basic difference between the two facilities was the tank width. 

 One pair of tanks, each 6 feet (1.8 meters) wide, was used for experiment 

 70X-06; the other pair, each 10 feet (3 meters) wide, was used for experi- 

 ment 70X-10. The initial test length, from generator to Stillwater level 

 (SWL) intercept on the slope, was 100 and 61.7 feet (30.5 and 18.8 meters) 

 in experiments 70X-06 and 70X-10, respectively (Table 1) . 



During the experiments, it became evident that the backshore length 

 was too short, because the steady erosion of the sand slope caused the 

 shore to reach the end wall of the tank after 54 hours in experiment 

 70X-06 and after 62 hours in experiment 70X-10. From then until the end 

 of the experiments, sand was periodically added to the backshore to main- 

 tain an adequate supply. In effect, the erosion was stabilized by 

 beach replenishment. 



II 



