Table 6 



Historic Variation In Potential Sediment Transport (Profiles from Batliymetry) 



Profile 



Line 2 (1,350 m North of Jetties) 



Line 3 (2,200 m South of Jetties) 



Line 4 (8,200 m South of Jetties) 



To the 

 South (m') 



To the 

 North (m') 



Net 



To the 

 South (m^ 



To the 

 North (m^ 



Net (m^ 



To the 

 Soutti (m^ 



To the 

 North (m^ 



Net 

 (m^) 



1945 



198,433 



-140,006 



58,427 



259,371 



-207,176 



52,195 



252,442 



-197,966 



54,476 



1965 



227,909 



-170,208 



57,701 



215,441 



-158,792 



56,649 



234,210 



-176,583 



57,627 



1991 







- 



200,708 



-145,711 



54,997 



240,022 



-186,383 



53,639 



1995 



240,158 



-184,706 



55,191 



198,293 



-141,720 



56,573 



173,002 



-116,738 



56,264 



Note: 1. Transport calculations from average annual wave conditions (WIS Station M59). 

 2. Ice conditions were considered. 



1995 bathymetry and the annual average wave climate from 1956 to 1987 at 

 Station M59. 



Due to lower rates of northerly transport, the south fillet beach is smaller 

 than the north fillet beach. The potential rate of annual channel infilling 

 during southerly wave attack is estimated to be 8,500 m^/year (see Fig- 

 ure 14b). The combined annual rate of channel infilling is estimated at 

 23,500 m^/year. Annual variations in wave energy could result in much higher 

 channel infilling in any given year. 



The rate of natural bypassing will be significantly less than the estimated 

 potential infilling rate. 



Results of Cross-Shore Modeling with Multiple 

 Grain Sizes 



With the new capabilifies of the C0SM0S-2D model to include multiple 

 grain sizes for a single profile, the cross-shore model tests for Profiles R9 and 

 R14 were repeated with 0.2-mm sand offshore and 2.0-mm sand in the near- 

 shore and beach. Also, an additional low water level condition was considered 

 for the 24 January 1992 storm to examine the influence of low water levels on 

 cohesive profile exposure and bar movement. It should be noted that the mul- 

 tiple grain size version of COSMOS does not include the ability to simulate 

 the mixing of grain sizes across the profile (i.e., the various grain size zones 

 remain fixed in position). 



For Profile R9, located at the feeder beach, the erosion and deposition 

 trends predicted with the multiple grain sizes were similar to the results for a 

 single grain size as presented in Parson, Morang, and Nairn (1996) (see Fig- 

 ures 15 to 17). Erosion of the sand cover results in exposure of the underlying 

 fill in some areas. The width of the exposed till was not influenced by water 

 level; however, the location of the till exposure was influenced by the different 



Chapter 4 Analyses of Coastal Processes and Geomorphology 



31 



