An improved equation for predicting reflection coefficients with less error 
in the estimates is 
Ky = — = (15) 
where a and £8 are empirical coefficients determined from the laboratory 
data (e.g., Fig. 4). The value of 8 increases as the slope becomes flatter 
and is larger for irregular waves than for monochromatic waves (Fig. 5). For 
slopes with cot® < 6, the suggested prediction coefficients are a = 1.0 and 
8 = 5.5 with the equation, 
MOEN 
52 + 8 
Ky 
whichever (16) 
or : 
is smaller 
K, = a tanh (0.1 £2) 
@ Irregular Waves ( Ahrens, 1980) 
O Monochromatic Waves (Ursell, Dean, and Yu, 
1960; Moraes, 1970; This Study ) 
ce) 
O f 2 B.S BGR BO sitive 1s 14 16 16 
cot 8 
Figure 5. 8 as a function of structure slope. 
2. Breaking at the Toe or Seaward of the Structure. 
If the water depth at the toe of the structure is less than five times the 
incident wave height or if the wave steepness is large, significant additional 
wave energy loss may result from wave steepness/water depth-limited breaking. 
The dimensionless ratio describing this type loss is the ratio of the incident 
wave height to the maximum possible breaker height, (H;/Hp) » where Hp is 
given by equation (7). This ratio includes the influence of offshore slope, 
water depth at the toe of the structure, and wave steepness, and gives a meas-— 
ure of breaking at the toe. The suggested empirical coefficient to account 
for this type energy loss in predicting reflection coefficients is 
: Hi Lod 
a = exp {—- 0.5 il (aL) 
for use with equation (16), where a is a reflection coefficient reduction 
factor. 
