unrealistic because of the added complexity and because the movement and 

 mixing of individual grains are not simulated in the model. 



Results 



499. Calibration . Figure 78(a and b) illustrates the result of a 

 typical calibration for one event (840403-840406) together with the wave and 

 water level data. The initial measured profile is displayed together with the 

 measured and calculated final profiles. Movement of the bar was rather well 

 predicted by the model regarding location, but the amount of material moved 

 was underestimated, and the trough was not sufficiently pronounced. Also, 

 even though a larger equilibrium energy dissipation was used on the foreshore 

 corresponding to the measured 2 -mm grain size, the simulated shoreline still 

 receded somewhat, whereas this did not occur in the field. One reason for 

 this retreat was transport produced by small waves that passed over the bar 

 and broke immediately on the beach face. Indeed, wave breaking at the step is 

 commonly observed at the FRF; nevertheless, little shoreline movement takes 

 place. Application of the concept of cross -shore transport being proportional 

 to energy dissipation may be questionable if a surf zone is absent and waves 

 break directly on the beach face. Lack of shoreline movement at the FRF is 

 anomalous, and model results cannot be interpreted in this region based on the 

 data. 



500. Verification . Optimum parameter values determined from the 

 calibration were used to simulate an independent storm event (821207-821215), 

 and thus evaluate the applicability of these values for an independent 

 erosional case. The result of the model verification is shown in Figure 79 (a 

 and b) , together with the input wave height, wave period, and water level. 



The initial beach profile exhibited two bars, with the outer bar having a very 

 smooth shape. The model simulation reproduced the main changes of the beach 

 profile in that both bars moved offshore. However, the amount of material 

 moved was underpredicted as in the calibration, and the calculated shoreline 

 receded farther than the measured. Movement of the inner bar was overes- 

 timated by the model, whereas the outer bar was located correctly but with 

 less volume than measured. Also, the long, smooth trough located shoreward of 

 the outer bar was not produced in the model simulation, and only a small 

 amount of material was eroded from this region. 



209 



