and beach widths between profile lines, there are some interesting differences 

 between Figures 10 and 11. For example, profile line 16, which was only 

 seventh highest in bluff recession, was second in volume eroded. 



Profile lines 4 and 16, which lost the greatest volumes, are both located 

 within the influence of a shore protection structure. Davis, Fingleton, and 

 Pritchett (1975) attributed the high amount of bluff recession in 1972 at 

 profile line 4 to a nearby seawall. The dramatic increase in bluff recession 

 and volume loss in 1974 at profile line 16 was attributed to a 579-meter-long 

 seawall completed during the study (Birkemeier , 1980). Because these two 

 profile lines were locally affected, they were separated from the remaining 

 profile lines and are discussed in Section V, 4. 



3. Lake Levels and Storms. 



Birkemeier (1980) found that the average rate of bluff recession from 

 November 1970 to November 1974 correlated well with the occurrence of storms 

 and correlated inversely with the seasonal variation in lake level. The study 

 area was a 1.6-kilometer reach of beach located north of profile line 16. 

 This finding is supported by the present study which includes more frequent 

 measurements over a larger area during approximately the same time period. 

 This same relationship is shown in Figure 12, which graphs the combined total 

 bluff recession by year and month for 15 profile lines, excluding lines 4 and 

 16. Note that peak bluff recession occurs just before and after ice breakup. 

 Minimum recession occurs during the ice cover period and during the summer 

 months. 



22 



20 

 18 

 16 



c 

 o 



■« 12 



a> 

 u 



(Sic 

 I 8 



I I Jan, -Dec. 1974 



W^ Jon. -Dec. 1973 



W^ Jan. -Dec. 1972 



^H Jon. -Dec. 1971 



Moy June July Aug. Sept 



Figure 12. Cumulative bluff recession for 15 profile 

 lines (excluding 4 and 16), by month and year. 



27 



