465. It was possible to obtain better agreement between simulated and 

 measured bar locations by changing model calibration parameters. However, it 

 was not possible to simulate berm buildup on the foreshore because the 

 empirical criterion for the transport direction (Equation 2) predicted 

 seaward-directed transport during the entire run. Wave and sand parameters 

 for Case 911 are such that the intersection of quantities involved in the cri- 

 terion determining transport direction is very close to the line separating 

 bar and berm profiles. This may explain the somewhat mixed response of the 

 profile. 



Water level, wave height, and wave period 



466. To qualitatively evaluate model performance for varying water 

 level, wave height, and wave period, a number of hypothetical cases were 

 simulated. In all cases, the initial beach profile consisted of a dune with a 

 steep face having a plane slope (1:5) joined to a more gentle plane slope 

 (1:15) at the still -water shoreline. The cycle of the variation for wave 

 period, wave height, and/or water level was set at 200 time -steps (At = 5 

 min) , and the simulation was carried out for 1,000 time -steps. 



467. The effect of a varying wave period was investigated first, where 

 the deepwater wave height was chosen as 2.0 m and the water level was fixed. 

 The wave period was varied sinusoidally between 6 and 10 sec with the pre- 

 viously-mentioned time cycle. Figure 71 shows the simulated beach profile at 

 selected time-steps and the wave height distribution at the last time-step. 

 The shape of the bar is somewhat more gentle than for a fixed wave period (see 

 Watts 1954) and changes in the profile decrease with time, approaching a near- 

 equilibrium state, even though the wave period continues to change. The 

 direction of bar movement was seaward during the entire simulation period. 



468. Beach profile change produced by a sinusoidally varying water 

 level showed features similar to those in the Case 911 simulation. The 

 simulated example had a water-level amplitude of 1 m, a wave height of 2 m, 

 and a wave period of 6 sec. Figure 72 shows the calculated beach profile at 

 selected time -steps and the wave height distribution across -shore at the last 

 time -step. As the water level increased, the bar was stationary or even moved 

 some what shoreward, whereas during the decline in water level the bar moved 

 rapidly seaward. Once the bar formed, a rise in water level allowed waves to 



195 



