coefficient is seen to increase slightly whereas the observed 

 reflection coefficients exhibit a decreasing trend with increasing 

 wave steepness. As discussed previously this trend of the experimental 

 reflection coefficients is generally observed and may be partly due to 

 experimental errors in the determination of the reflection coefficient. 

 This was discussed briefly in Section II. 3. b and in detail in Section 

 III.3.b. 



The transmission coefficients predicted based on the assumption 

 AHg/AHj = 1 are seen to be lower than the experimentally obtained 

 values. This, of course, is the expected type of discrepancy since 

 the runup on the seaward slope of the trapezoidal breakwater is almost 

 certain to exceed the runup on the equivalent rectangular breakwater. 

 Adopting the theoretical value of the runup, R^, on the trapezoidal 

 breakwater predicted by the procedure developed in Section III of this 

 report is expected to give transmission coefficients slightly on the 

 high side as discussed in Section IV. 3. c. This anticipated behavior is 

 not exhibited by the predicted transmission coefficients plotted in 

 Figure 26. In fact, the agreement between observed and predicted 

 transmission coefficients is excellent. 



A slightly different estimate of the runup on the seaward slope of 

 a trapezoidal breakwater may be obtained by adopting, for example, 

 the results obtained by Jackson (1968), who reported values of R 

 approximately equal to unity for test conditions similar to those of 

 Sollitt and Cross (1972). In the present case this value of R^ would 

 result in a slightly lower prediction of the transmission coefficient 

 than the prediction indicated by the full line in Figure 26. 



The procedure developed here for the prediction of transmission and 

 reflection coefficients of a trapezoidal, multilayered breakwater did 

 not rely on the experimental data shown in Figure 26 to obtain a "good 

 fit". The overall comparison between predicted and observed transmission 

 and reflection coefficients, which is analogous to the comparison given 

 by Sollitt and Cross (1972, Fig. 4-14), must therefore be considered 

 very good. 



99 



