The energy dissipation coefficient from Figure 2 is K4 = 0.86, 86-percent dissi- 
pation or 17 percent more dissipation than occurred for the smooth slope (see 
example problem 1). Sample predicted reflection coefficients are given in 
Figure 13. The preliminary information in Table 2 suggests that further re- 
duction in the reflection coefficients could be achieved by adding a second 
layer of armor (n = 2) for wave heights less than 3 meters Giilceeel Sir 
1.0 p=TOks 
cot @=2.0 
ree dg = 7.6m 
0.8 W = 4,500 kg 
0.7 
Kr 0.6 
0.5 
0.4 
Os) 
0.2 
0.1 
O OFS 1.0 1.5 20 2.5 3.0 33,5) 4.0 4.5 
H; (m) 
Figure 13. Wave reflection coefficients for a smooth revetment 
and revetments with one and two layers of armor stone. 
VIII. SUMMARY 
Methods for predicting wave reflection and dissipation coefficients for 
beaches, nonovertopped revetments, and breakwaters are presented. Types of 
wave energy dissipation considered are wave breaking induced by the structure, 
wave breaking at the toe of the structure, turbulence produced by wave inter- 
action with the outer layer of armor, and flow through additional layers of 
armor. These techniques are combined with the method of Madsen and White 
(1976) to estimate reflection and transmission coefficients for permeable 
rubble-mound breakwaters. Factors considered when making reflection coeffi- 
cient estimates include structure slope, water depth at the toe of the struc- 
ture, offshore slope, incident wave height and period, the size and number of 
layers of armor units, and the type of structure. Techniques presented apply 
to breaking and nonbreaking (surging) waves and can be used for monochromatic 
and irregular wave conditions. 
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