No mention is made in Moore and Cole (1960) of how or where the wave height, 

 period, and angle between wave crest and beach are measured. Saville assumes 

 that they are deepwater values and the SPM assumes that the wave height is 

 significant wave height. The computed value for P^g is larger by nearly an 

 order of magnitude than in the other field data and hence does not plot on the 

 scale of Figure 4-37 of the SPM. It would plot below the line in Figure 4-37 

 given by equation (C-1) . 



Fourteen data points are taken from Komar (1969) , 10 from work at El Moreno 

 Beach, Mexico, and 4 from Silver Strand Beach, California. The longshore trans- 

 port rate, Q, -was calculated from the movement of fluorescent tracer sand, 

 determined from the amount and location of the tracer sand in regularly spaced 

 core samples taken on the beach about 3 to 4 hours after injection of the tracer. 

 Wave energy flux and wave direction were measured by an array of digital wave 

 sensors (wave staffs and pressure transducers) in the nearshore region. Inte- 

 grating the energy densities under the spectra peak of the records of these 

 wave sensors gives the mean square elevation of the water surface, <ri^>. The 

 energy of the wave train is then 



E = pg <n2> (C-7) 



The wave period of the wave train is at the point of maximum energy density 

 for the particular spectra peak being analyzed. By knowing the water depth_^ 

 group velocity can be found. The wave energy flux per unit crest length, EC„, 

 may now be calculated. Comparing wave records of various gages of the array 

 produces the wave angle, a, which gives 



wave energy flux zr^ 



— • . 1 r — 1 TT - bC„ cos a 



unit beach length 9 



Assuming no energy dissipation until breaking, the energy flux per unit beach 

 length at the breaker zone is 



(EC cos a), = EC^ cos a (C-8) 



Equation (C-8) is then multiplied by the sin a^,, where ajy is measured in 

 the surf zone or calculated from a using Snell's law 



sin a-, = jr- sin a (C-9) 



to give the energy flux factor 



Pj^ = (EC cos a), sin a, (C-10) 



In (C-9) , Cj, is evaluated from phase speed near breaking assumed to be (Komar, 

 1969) 



Cj, = (2.28 gH^)l/2 (C-ll) 



Note that Komar uses rms wave height to compute values for Pj;,^. To make his 

 values consistent with the other field data points in Figure 4-37 of the SPM, 



32 



