The actual monthly variation in the rate of lake level change was periodic 



during the study; therefore, the true effect of the average rate of lake level 



change during each study period is difficult to identify using photos spaced 

 at regular intervals each year. 



The value of the regression exercise is to identify the importance of short- 

 term storm effects (as indicated by W) on the bluff recession rate. 



To test Seibel's (1972) linear relationship between average lake level and 

 long-term bluff recession rates, the average changes for all reaches over the 

 four periods (Table 10; ice days included) were combined with data from other 

 sources (Table 11). The results (Fig. 36) further support a strong lake level 

 dependence. 



(ffl 



6.5 

 6.0 

 5.5 

 5.0 

 - 4.5 

 ^ 4.0 



a> 



^3.5 



c 

 o 



•^ 3.0 



a> 



Q: 2.5 



m2.0 



1.5 



1.0 



0.5 



579 



-r- 



• This Study 

 o Seibel (1972) 

 + Tenner ( 1975) 

 A Michigan Department of 

 Notional Resources ( 1974 ) 



175.8 



176.0 



176.2 176.4 176.6 



Avg. Loke Level ( m ) 



176.8 



177.0 



Figure 36. Effect of lake level on the bluff recession 

 rate (data are from Tables 10 and 11). 



57 



