area (PL-9, PL-10, and PL-11). By comparing these profiles with the pro- 

 files in Figure 14, it is apparent that PL-11 is intermediate in develop- 

 ment, less mature than PL-0, but more mature than PL- 5. Figure 16 gives 

 ridge slip-face migration rates for profiles PL-4, PL-9, and PL-10, rep- 

 resenting the central and northern end of the study area. The figure 

 shows that migration rates are approximately equal for these locations. 

 Although migration rates are similar for these locations, a greater vol- 

 ume of sand was transported shoreward on profiles PL-9 and PL-10 than on 

 PL-4. The greater amounts of sand transported at PL-9 and PL-10 is a 

 result of the distance of the nearshore bar from the beach at the dif- 

 ferent profile locations (Fig. 17) , the closest bar between PL-9 and 

 PL-11. 



Typical accretionary profiles between 13 July and 12 August are shown 

 in Figures 18 and 19. In Figure 19, profile PL-0 has assumed a "late 

 mature" profile, characterized by a broad berm, a relatively steep beach 

 face, and a lack of any large-sized ridge and runnel systems. On profile 

 PL-6, the position of the last high tide swash was located approximately 

 41 meters landward of the same last high tide swash on PL-0 (on 1 and 2 

 August). The last high tide swash on PL-11 was about 14 meters seaward 

 of the last high tide swash on the beach face of PL-6. The southern pro- 

 files remained most mature, with the northern profiles less mature, and 

 the central profiles at a lesser stage. The relative maturity of a given 

 profile depends primarily on how quickly sediment is moved landward after 

 a storm. During a storm, the backshore and foredune ridges at the north- 

 ern and southern ends of the study area are less likely to erode than the 

 same features between profiles PL-4 and PL-8 because of the shielding 

 effect of the large berm. 



2. Preweld Period . 



The preweld period of beach morphology (before 12 July) is shown in 

 Figures 20 and 21. The figures show a typical early accretional beach 

 with a large ridge, a wide runnel (16 meters), and an active beach face 

 shoreward of the ridge. The ripples in the runnel were formed by sub- 

 critical flow at or near high tide. The ridge migrated shoreward as the 

 ridge surface became flooded before high tide. Sediment was transported 

 across the ridge surface, primarily under upper flow regime conditions, 

 and deposited on the ridge slip face as flow separation took place. In 

 Figure 22, the first swash has partially overlapped the ridge surface. 

 Sediment is transported across the ridge surface either in a sheetlike 

 manner or in the form of small ridges. Figure 23 shows flow separation 

 occurring over the slip face of the ridge. Flow conditions are not 

 always uniform over the slip face as shown by the current eddys in the 

 figure. 



As the ridge moves shoreward toward the backshore, the ridge gradient 

 (measured from the ridge crest seaward) undergoes a progressive steepening 

 (Fig. 24). On 2 July, the ridge gradient at PL-6 was 0.035 centimeter 

 per centimeter, while the high tide beach-face gradient for the same 



35 



