range, for up to 12 selected depths. The coordinate system used for 

 the contour movement plots is shown in Figure 5. 



The following elevations are referred to in the discussion that 

 follows: 0.2 foot (6.1 centimeters), 0.3 foot f9.1 centimeters), 0.4 

 foot (12.2 centimeters), 0.5 foot (15.2 centimeters), 0.6 foot (18.3 

 centimeters), 0.7 foot (21.3 centimeters), 0o8 foot (24.4 centimeters), 

 0.9 foot (27.4 centimeters), 1.2 feet (36.6 centimeters), 1.4 feet (42.7 

 centimeters), and 2.1 feet (64.0 centimeters). 



b. Profile Zones . Definitions of coastal engineering terms used in 

 LESS reports conform to Allen (1972) and the Shore Protection Manual (SPM) 

 (U.S. Army, Corps of Engineers, Coastal Engineering Research Center, 1975) 

 For the profile zones in this study, the boundary between the foreshore 

 and inshore zones is defined at elevation -0o2 foot. 



The seaward edge of the inshore zone is defined as extending through 

 the breaker zone. The boundary between the inshore and offshore zones 

 for these experiments is at elevation -0.8 foot. 



A definition sketch of the profile zones is shown in Figure 6. The 

 profile in each experiment developed in a similar sequence. Early pro- 

 files (broken line in Fig. 6) had a steep foreshore, a short inshore 

 zone with a longshore bar, and a gently sloping offshore zone. Later 

 profiles (dashline in Fig. 6) also had a steep foreshore zone, but the 

 inshore zone widened to a long, flat shelf which terminated in a rela- 

 tively steep offshore zone. This development is shown by contour move- 

 ment plots (Figs. 7 to 14) of the seawardmost contour intercepts for 

 elevations at 0. 1-foot-depth increments from +0.2 to -2.1 feet. Figures 

 7, 8, and 9 are for ranges 1, 3, and 5 in experiment 71Y-06; Figures 10 

 to 14 are for ranges 1, 3, 5, 7, and 9 in experiment 71Y-10. The heavier 

 lines for the -0.2- and -0.8- foot contours distinguish the three profile 

 zones in the figures. In the foreshore and offshore zones the contour 

 lines are close together indicating steeper slopes; in the inshore zone 

 the lines are spaced farther apart indicating flatter slopes. 



(1) Foreshore Zone . Within the first hour of each experiment, 

 the foreshore developed the basic shape which it maintained throughout 

 experiment 71Y-10 and until the wave period was changed in experiment 

 71Y-06, as shown in the contour movement plots of the foreshore zone for 

 the first 10 hours of experiments 71Y-06 (Fig. 15) and 71Y-10 (Fig. 16). 

 The foreshore maintained basically the same shape (see Figs. 7 to 14) but 

 retreated as material was eroded from the foreshore and backshore (upward- 

 sloping lines in the figures) . 



Although the contour lines of the foreshore moved together, the lines 

 were not always parallel, indicating a variation in foreshore slope with 

 time at each range (Figs. 7 to 14). Table 9 gives slope values at the 

 SWL intercept for the regularly surveyed profiles in experiments 71Y-06 

 and 71Y-10. The steepest slope was about 0.56, and the flattest slope 

 was 0.08; the average slope was about 0.20. 



31 



