Table 3 



2-D COSMOS Modeling, St. Joseph Harbor, 



Michigan 









Profile 







Average Annual Alongshore Sediment Transport 









0.2 mm 







0.4 mm 







2.0 mm 





North 



South 



Net 



North 



1 



South 



Net 



North 



South 



Net 



8 



-306,278 



375,328 



69,050 



-139,824 



154,371 



14,548 



-50,415 



59,400 



8,985 



9 



-291,765 



366,579 



77,814 



-135,758 



159,492 



23,733 



-44,893 



55,421 



10,528 



10 



-263,469 



339,963 



81,032 



-122,982 



148,291 



25,309 



-40,369 



46,205 



5,836 



11 



-282,591 



353,817 



71,667 



-131,671 



154,095 



22,424 



-42,284 



47,180 



4,896 



12 



-283,712 



355,381 



71,669 



-130,454 



150,601 



20,147 



-44,679 



48,856 



4,176 



14 



-100,086 



170,794 



70,708 



-51,092 



79,898 



28,705 



-16,702 



24,592 



7,890 



17 



-165,290 



243,799 



78,509 



-86,394 



118,091 



31,696 



-28,008 



34,839 



6,831 



20 



-149,609 



255,142 



105,533 



-79,146 



119,323 



40,176 



-25,454 



35,084 



9,629 



22 



-259,066 



336,333 



77,266 



-124,627 



149,683 



25,506 



-45,283 



50,678 



5,395 



23 



-155,016 



231,740 



76,724 



-75,257 



104,680 



29,422 



-24,614 



32,392 



7,777 



Note: Pos 



tive transport 



is south. 

















from the south have little or no effect on the sediments trapped in the shadow 

 of the north jetty). 



Alongshore sediment transport calculations were performed for a djg of 

 2.0 mm in the final series of these runs. The results are summarized in 

 Table 3 and presented in Figure 7. Importantly, these findings indicate that 

 only as little as 50 percent of the coarse sediment eroded from the feeder 

 beach would make its way past Line R23 and south of the study area. The 

 remaining 50 percent of the coarse sand eroded from the feeder beach is prob- 

 ably deposited in the depression located offshore of the MOOT and railway 

 revetments. 



Multiple grain sizes across a profile 



The COSMOS-2D model was upgraded to simulate multiple grain sizes 

 across a beach profile and alongshore sediment transport calculations were 

 redone for Lines R12 and R14. A dgp of 0.2 mm was assumed for the off- 

 shore sediments of both profiles, with a gradual coarsening from 0.2 mm at the 

 swash zone to 2.0 mm at the shoreline. 



Results for the single dgg and multiple djg's are compared in Table 4. At 

 Line R12, the COSMOS-2D model tests with a multiple grain size resulted in 

 a 25-percent reduction of northerly and southerly transport from the 0.2-mm 

 results of the first investigation. This is attributed to the coarsening of the 



18 



Chapter 4 Analyses of Coastal Processes and Geomorphology 



