Table 5 



Annual Variability In Potential Alongshore Transport (1992 Profiles) 



Year 



Avg. 

 Direction 

 (deg from N) 



Wave 



Energy 



(m2/s) 



R12 (1992) 



R14(1992) 



To the 

 South (m^ 



To the 

 North (m^ 



Net (m^ 



To the 

 South (m^ 



To the 

 North (m^ 



Net (m^ 



1964 



279 



34,000 



375,350 



-379,867 



-4,517 



231,993 



-196,583 



35,410 



1965 



289 



40,000 



625,108 



-433,064 



192,044 



442,246 



-227,578 



214,668 



1971 



287 



44,000 



654,857 



-481,967 



172,890 



482,302 



-298,929 



183,373 



1974 



283 



25,000 



376,879 



-329,032 



47,847 



247,197 



-162,939 



84,258 



1977 



293 



46,000 



741,016 



-382,582 



358,434 



493,753 



-226,542 



267,211 



1983 



308 



21,000 



364,927 



-164,594 



200,333 



236,383 



- 84,622 



151,761 



1986 



290 



17,000 



235,452 



-135,719 



99,733 



129,425 



-48,728 



80,697 



Note: 1 . Ice conditions were not considered for annual time series data. 



2. Offshore d^g = 0.2 mm and beach djQ = 2.0 mm. 



3. Wave energy (m^/s) is Hg^Tp {wave height squared x peak period) - provides indication of relative wave energy. 



direction was 279 deg from north, which is close to the shore-perpendicular 

 profile azimuth selected for the profiles at SL Joseph. (Consequently, the esti- 

 mated net transport for 1964 was very close to zero. Of the 7 years selected 

 from the WIS data at M59, 1977 recorded the maximum wave energy 

 (46,000 m^/s) and the highest net southerly transport rate component of 

 382,600 m^/year. 



Although the net transport rates for R12 and R14 are fairly similar, the 

 southerly and northerly components at R14 are much lower than the results for 

 R12, perhaps due to the deeper profile offshore of the revetment at R14. 



Historic variability in potential alongshore sediment transport 

 related to profile change 



Sediment transport calculations were completed at three historical profile 

 lines, Nos. 2, 3, and 4, to determine the influence of long-term profile change 

 (Figure 10). The profiles were generated from the 3-D surfaces created from 

 the historic bathymetry. SelecUon of the four profile locations was based on 

 the following assumptions about the nearshore conditions and profile evolution 

 prior to the comparison of the data: 



a. Line 1. Updrift cohesive profile (no influence from fiUet/harbor jet- 

 ties - representative of natural conditions or background erosion rate). 



b. Line 2. Updrift fiUet profile (influenced by harbor jetties). 



Line 3. Downdrift cohesive profile (reduced sediment supply - influ- 

 enced by the harbor jetties). 



Chapter 4 Analyses of Coastal Processes and Geomorphology 



25 



