identical to that chosen for the transport rate distribution on the foreshore 

 for erosional transport. The linear shape of the transport rate on the 

 foreshore was supported by the data analysis for both onshore and offshore 

 transport. 



520. Parameter values used in the breaker decay model are identical to 

 the ones applied for erosional conditions, and these values are considered to 

 be representative averages for various slopes. Also, the same criterion for 

 incipient breaking is applied for both erosional and accretionary transport 

 conditions, although this was primarily derived from cases showing erosion and 

 having a distinct breakpoint bar. 



Berm simulation 



521. Case 101 from the LWT experiments was used to qualitatively 

 evaluate the capability of the model to simulate beach profile accretion. As 

 shown in Figure 84, a berm rapidly formed on the foreshore by onshore trans- 

 port from breaking waves, and material was deposited up to the limit of runup. 

 As sand was transported onshore, the surf zone and offshore eroded, increasing 

 the depth along this portion of the profile. The increase in depth caused the 

 break point to move onshore and, at about the same time, the berm retreated 

 somewhat at the shoreline while its seaward slope became steeper. Continuous 

 onshore movement of the break point made the surf zone become narrower through 

 time, restricting the onshore transport to a smaller area of the profile. The 

 seaward berm slope steepened because of the continuing transport, limited only 

 by the angle of initial yield. The angle of initial yield had to be reduced 

 somewhat on the foreshore to achieve a less steep slope, considered realistic 

 because of the strong turbulent conditions. A large region of erosion 

 appeared immediately seaward of the foreshore, where a deep trough developed, 

 allowing waves to break at the beach face. 



522. The profile approached equilibrium, exhibiting a well-formed berm 

 together with a deep seaward trough. The measured and simulated berm volume 

 and location are in good agreement. However, the seaward slope of the berm 

 grew too steep in the numerical simulation, and the profile shape in the surf 

 zone was not well reproduced. The small bar that developed slightly shoreward 

 of the breakpoint in the wave tank was not obtained with the model. The main 



221 



