V(m/s) 



V(m/s) 



0.5 



0.0 



- 





fVmo. 





■ 



MEASUr 



ED / 



•—^ 



■ 





1 Vm.o« 



/ \ 



\, , , , • 





^BREAKER LINEX 



PRESEN 



T MODEL / 



■r [ 1 1 1 





-200 



150 



100 -50 

 x(m) 



50 



Figure 63. Jonsson, Skovgaard, and Jacobsen's longshore current profile 

 versus laboratory and field data (after Jonsson, Skovgaard, 

 and Jacobsen, 1974) . 



V (measured) - v(predicted ) 

 v(predicted) 



(160) 



was employed and its mean and standard deviation used in the analysis. 

 For the Putnam, Munk, and Tray lor (1949) data v = <v>, the average over 

 the surf zone; for the data for Brebner and Kamphuis (1963) v = Vj^, the 

 maximum longshore current; and for Galvin and Eagleson (1965) data, only 

 the denominator was <v> . In all cases tested, the standard deviation was 

 .such that an accuracy of ± 15 percent was expected for their nonlinear 

 longshore current model (Ostendorf and Madsen, 1979, p. 147). The model 

 tended to underpredict current magnitudes for beach slopes flatter than 

 1 on 10. ~ A weak current small-angle (linear) model was also tested and 

 and found to be less accurate. 



177 



