are developed for use in the profile change model. The next section gives a 

 description of the numerical solution scheme and the associated boundary 

 conditions. Finally, calibration and verification of the profile change model 

 with the LWT data set are made. Applications of the model, including 

 sensitivity analyses and tests of predictions with field data, are given in 

 Part VII. 



Wave Model 



388. As waves approach shore over a gently sloping bottom, they 

 increase in height and decrease in length due to shoaling. It will be assumed 

 that the waves are incident normal to the coast, i.e., that refraction can be 

 neglected. The increase in wave height continues until some critical ratio is 

 reached between wave height and water depth, at which point the waves break. 

 The wave height distribution across the shore is calculated by linear wave 

 theory. In initial model development, the nonlinear shoaling laws proposed by 

 Shuto (1974) were used in an effort to provide an improved description of the 

 increasing nonlinearity of waves as they approach breaking. However, in 

 comparison of predictions of the nonlinear wave model against wave height 

 measurements from the CRIEPI data set, the predicted height increased too 

 steeply before breaking for longer-period waves. In simulations involving 

 development of a prominent breakpoint bar through time, the wave height just 

 prior to breaking was overestimated. It was thus decided to use linear wave 

 theory in all regions of the shoaling calculation and leave the problem of 

 nonlinear wave shoaling to the future. 



Breaking criterion and breaker height 



389. The ratio of wave height to water depth at breaking (called the 

 breaker index) was evaluated using the CRIEPI data set. Only those cases with 

 an initially plane slope were used and, if no profile survey was taken at the 

 time of the wave height measurement, the depth at breaking was determined by 

 interpolation from the two profiles bracketing the wave measurement in time. 

 In total, 121 pairs of wave height and depth values were obtained from 17 

 cases having different wave conditions and initial beach slopes. The average 

 breaker index (wave height to water depth at breaking) was 1.00, with a 



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