O Beach slope 1 : 12 (Bowen, Inman 8. Simmons) 

 I- O - - 1:15 I 



D - - 1 , 30 1 ^ 



(Saville) 



' Spilling breaking 

 I I III I I I I 



_l I I L_L. 



10-^ 

 Hq/Lc 



Figure 53. 



Maximum wave setup dependent upon deepwater wave steepness and 

 beach slope (after Jonsson and Buhelt, 1978). 



In summary, for nonlinear regular wave theory. It is tentatively con- 

 cluded that excellent results are attainable for wave setdown calculated 

 by equation (155) from cnoidal theory, and that the theory of James (1972, 

 1974a) requires further comparison with experimental results. All wave 

 setup theories still require assumed values for the wave breaking ratio, y- 



Only the laboratory scale experiments by Battjes (1972, 197Aa) and 

 Goda (1975) are available to test the theory for irregular waves. The 

 theory of Collins (1972) has never been compared with measured values. 



Battjes used a 100-meter-long and 2-meter-wide basin with a water 

 depth of 0.55 meter in the horizontal section. Beach slope was 1:20. Two 

 examples of measured and computed wave setup (based on theory of Battjes, 

 1972, 1974a) are shown in Figure 54. A systematic difference between theory 

 and measured laboratory data was observed in both cases, (a) mean period T^ 

 = 1.2 s; rms, incident height, Hq = 8.2 centimeters, (b) mean period Tq 

 = 2.0 s; rms, incident height, Hq = 8.5 centimeters, with the theory 

 always giving too high a wave setup. Wave setdown values were very close 



165 



