d, cL d L 



j^ = 0.0724 and ^ = ^ . ^ = 0.0308 

 b o b o 



(b) Linear theory 

 H 



r 



Determine 



,4/7 

 From Figure 18 



= 0.148 



L S 

 o 



= 12.2° 



Snell's law 



Wave height 



Depth at breaking 



L sina 

 o o 



0.329 



0.76 cos 



1/7 



H -1/4 3/4 

 ( ^) K =1,115 



o 



= 0.3417 



IV. SUMMARY AND CONCLUSIONS 



It appears that no single wave theory accurately predicts the trans- 

 formation of a wave from deep to shallow water. In shallow water, cnoidal 

 theory successfully describes the shoaling of wave height but overestimates 

 the wave celerity and wavelength. All previous studies emphasize an accurate 

 determination of wave height, but little attention is paid to the wavelength. 



When considering longshore currents and sediment transport the angle 

 of wave breaking becomes a parameter of high importance and, therefore, also 

 the wave refraction process which is intimately connected with wavelength. 



In this study a "hybrid" wave theory is proposed, consisting of 

 cnoidal wave height and linear wavelength transformation in the regime where 

 cnoidal theory applies. In comparison with existing data this theory is 

 found to predict wave height and wavelength better than previous theories. 



36 



