Y)i = median diameter of the beach sediment in the breaking zone 

 (in millimeters) ; 



H = wave height in the wave fliime (in meters) ; 



y' = submerged unit weight; 



Aj = a constant (=43.5) for a wave flume but varies for wave basins 

 and shorelines; and 



m = slope of the beach face. 



Figures 28 and 29 compare the results obtained in this study with the 

 relationships of Sitarz (1963). In judging this data, the following should 

 be considered: 



(a) The observed Xq was taken as the distance from the Stillwater 

 line to the breaker; and 



(b) the beach face slope was taken as the. ratio of the elevation 

 change from the breaker point to the Stillwater line to Xq. 



The results from these experiments do not agree well with the relationship 

 of Sitarz. 



Although the observed values used for Xq and m do not satisfy the 

 definitions of Sitarz exactly, some relationship might be expected, e.g., 

 the relationships of Sitarz (1963) imply X '\^ y -^-^ for the same material 

 in model and prototype. 



Nicholson (1968) derived a relationship between Y^/Hq and Hq/Lq for 

 sand beaches,- where Y^ was defined as the vertical distance between the 

 crest of the bar and the crest of the beach for a "barred" profile, and 

 was defined as the vertical distance between the top of the step and the 

 crest of the beach for a "stepped" profile (see Fig. 4). Figure 30 

 presents the results obtained in these tests and shows no agreement between 

 the data collected and the relationship of Nicholson. 



In the case of very shallow water; 



U ^ 0.5 H g^/^ d'^/^ , (21) 



b max 



wh ere , 



U, = maximum orbital velocity at the bed; 

 b max 



H = local wave height; 

 g = gravity constant; and 

 d = local water depth. 



59 



