closure, D, , was either a constant (for example, 6 m or 8 m) or calculated 
from an expression given by Hallermeier (1979, 1983): 
Dy = 2.28 Ho > 10.9 (2) 
a lant 
in which H, is the significant wave height in deep water and L, is the 
deepwater wavelength. Equation 2 was developed for extreme wave conditions; 
H, and L, were originally defined to be the average of the respective quan- 
tities for the highest waves occurring during 12 hours in a year. Kraus and 
Harikai (1983) argued that for use with the one-line model, Equation 2 can be 
reinterpreted to hold as a function of daily input wave conditions. Numerical 
values for the depth of closure are given below in discussion of model cali- 
bration and verification. 
89. The predictive formula for the longshore sediment transport rate is 
taken to be 
Hp b i os 
Q=— GaIe a) K, sin (20, .) SP 20K a cot(8) (6.5) (3) 
where 
Hj, = breaking wave height 
Cob = wave group velocity at breaking 
S = ratio of sand density to water density (S = 2.65) 
a = sand porosity (a = 0.4) 
8p5 = breaking wave angle to the shoreline 
tang = average nearshore beach slope 
The quantities K, and K5 are transport parameters determined in calibra- 
tion of the model. 
90. The first term in Equation 3 corresponds to the CERC formula (Shore 
Protection Manual (SPM) 1984, Chapter 4) and describes sediment transport 
produced by obliquely incident breaking waves. The second term describes 
transport produced by a longshore variation in breaking wave height. The 
first term is always dominant, but the second term will provide a significant 
correction if diffraction enters the problem (Ozasa and Brampton 1980, Kraus 
1983, Kraus and Harikai 1983). 
91. The SPM recommends a value of Ky = 0.77 for root mean square wave 
height in Equation 3, and the coefficient K5 has been empirically found to 
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