0.5 



Ti^b o-^5 



(a) f = 0.004, N = 0.016 

 wc 



f = 0.004, N = 0.01 

 wc 



nonlinear theory 

 linear theory 



0.5 



I 

 of -f shore zone 



6ur-f 2.one 



(b) Linear theory 



•••• f = 0.004, N = 0.01, P = 2.09 



""^ 0.005 0,.01 1.67 



-- 0.004 

 — • 0.014 

 0.004 



0.016 



3.34 



0.01 



0.60 



0.05 



10.44 



Figure 37. Comparison between linear and nonlinear 

 theories of uniform longshore current 

 profiles (from Gourlay , 1978). 



2. Irregular Waves . 



In a wide range of circumstances, wave breaking is a local phenomenon in 

 an irregular (random) wave field that is qualitatively similar to individual 

 wave breaking. Both the type of breaker and the wave height at breaking are 

 similar. However, in the irregular wave surf zone there is no one given 

 breaker line since at each location only a percentage of waves passing have 

 broken, and this percentage varies gradually toward the shore giving rise to 

 average gradual variations of energy density, energy flux, momentum flux, and 

 other wave parameters. The dissipation of wave energy and resultant decrease 

 in radiation stress for irregular waves that break in the surf zone has been 

 the subject of extensive research by Collins and Wier (1969), Collins (1972), 

 and Battjes (1972, 1974). 



133 



