Table 2. Predicted and observed profile retreat. 



Study area 



Survey periods 

 1969-1971 1969-1975 1969-1976 

 X = 0.12 m X = 0.39 m x = 0.20 m 

 X = 870 m X = 1,020 m X = 923 m 







Average height. 



Z (m) 





Northern section 

 (stations 1 to 



Southern section 

 (stations 16 to 



Whole area 

 (stations 1 to 



15) 

 29) 

 29) 





10.84 12.15 

 12.90 14.28 

 11.86 13.21 





12.50 

 14.80 

 13.60 







Predicted retreat, 



Xz/Z ( 



m) 



Northern secton 

 Southern section 

 Whole area 





9.63 27.93 

 9.49 27.86 

 9.34 27.25 





13.92 

 13.78 

 13.57 







Observed retreat 



X (m) 





Northern section 

 Southern section 

 Whole area 





4.6 20.0 

 3.6 16.8 

 4.3 18.8 





12.6 

 14.8 

 13.6 







Overprediction 



(pet) 





Northern section 

 Southern section 

 Whole area 





109 40 

 164 66 

 117 45 





10 



7 

 



30|- 

 I 



E 20 - 



Slollont IS-E9 



SIOII(,r« J -29 



Slolloni I -IS 



1976 



Figure 20. Calculated versus measured retreat. The predicted ultimate retreat, in 

 response to post-1969 changes In mean lake level, exceeded the observed 

 retreat by more than 100 percent in 1971 and about 50 percent in 1975, 

 presumably because the active . prof ile had not had time to completely read- 

 just to the higher water ' levels. Almost perfect agreement had developed by 

 the time of the last survey, 3 years after the lake levels peaked. 



38 



