APPENDIX C 



Evaluations of the accuracy of the 

 photo interpreters' conclusions as to 

 depth and shallow area have been re- 

 ferred to in the text. Table 1 gives 

 detailed data from which the percentages 

 were drawn, covering the estimation of 

 shallow area by four different methods . 

 Note that somewhat consistent variation 

 is evident in the conclusions arrived at 

 by the three interpreters. Any given 

 interpreter may have a tendency to under- 

 estimate or overestimate; in preliminary 

 field training this might well be noticed 

 and thus be taken into account in actual 

 survey work. Also, because of their par- 

 ticiolar characteristics, certain lakes 

 were overestimated or underestimated by 

 all interpreters. 



The methods are as follows: 



Method A: 15 -foot depth contour 

 plotted on basis of vis - 

 ual estimates; shallow 

 area acreage obtained 

 ■ - from dot count. 



Method B: 15 -foot depth contour 



plotted on basis of par- 

 allax measurements of 

 bank slopes; shallow 

 area acreage obtained 

 from dot count. 



Method C: Average distance from 

 shore to 15 -foot depth 

 contour calculated from 

 parallax measurements; 

 proportion of shallow 

 area computed by ellipse 

 formula; acreage cal- 

 culated on basis of total 

 lake acreage obtained 

 from dot count. 



Method D: Shallow area computed 

 as in method C; result 

 adjusted by correction 

 factor of 1 . i6 . 



Table 1. --Estimates of shallow area of lakes made by three photo 

 interpreters, using four methods, as compared with shallow 

 area measured in the field (North Slope , Uinta Mountains) 



Lake no. : 



and total : 

 1 



acreage : 



Measured 



shallow 

 a 



area 





Shallow area estimated by: 





; Method A : Method B 



: Method C : Method D 











Acres - - - 













INTERPRETER 1 









9 ^ 1 



1 "7 c: 

 i . /D 



1. 17 



1.38* 



1 ^A* 

 X . oo 



1 R 1 * 



X . 



o . O / 



1 .75 



1.78* 



2. 14* 



t . OD 



1 * 

 Z . 10 



o 



0. 





2.83 



1 (\ 1 



1 . 1 



. 10 



/ . /o 



6 . ZU 



A 



4 , 



D . D-i 



. 10 



4.09* 



4.80* 



o . D / 





5. 



7.44 



A f\A 

 .U4 



5.12* 



4.83* 



4.80* 



5.57* 



6. 



8.78 



o .UU 



3.10 



5.18* 



5.15* 



5.97* 



7. 



9.83 



O OA 



o.Ud 



6.54* 



5.52 



5.57 



6.46* 



8. 



17.61 



8.98 



11.04* 



8.51* 



9.26* 



10.74* 



9. 



20.30 



18.67 



16.88* 



13.19 



11.71 



13.58 



10. 



22.31 



6.68 



11.00 



5.84* 



5.69* 



6.60* 



11. 



29.05 



20.74 



15.19 



17.94* 



11.59 



13.44 



12. 



32.36 



17.74 



13.67* 



16.70* 



13.01 



15.09* 



13. 



32.44 



15.63 



10.53 



16.43* 



15.12* 



17.54* 



14. 



40.30 



26.81 



29.40* 



26.44* 



18.30 



21.23* 



15. 



40.80 



18.89 



20.28* 



25.56 



19.50* 



22.62* 



16. 



41.12 



16.29 



24.20 



17.11* 



11.23 



13.03* 



17. 



63.91 



16.18 



37.91 



21.96 



18.34* 



21.27 









INTERPRETER 2 











1 .75 



2.41 



1.46* 



1 . /U 



1 Q7 * 







0.0/ 



1 . 75 



2.16* 



1.81* 



1 7Q + 



n 1 * 



Z . Ui 



3 . 



A t 1 



4 . Di 



2.83 



4.26 



3.10* 



Q on * 



o. / 1 



A 



4 . 



0.04 



5. 16 



4.72* 



5.28* 



J . UO 



, oO 



5. 



7.44 



6.04 



6.62* 



4.82* 



4.62* 



5.36* 



6. 



8.78 



6.00 



6.52* 



7.90 



8.56 



9.93 



7. 



9.83 



.Uo 



9.21* 



6.29* 



6.46* 



7.49* 



8. 



17.61 



8.98 



12.67 



8.81* 



10.14* 



11.76 



9. 



20.30 



18.67 



19.76* 



14.57* 



15.27* 



17.71* 



10. 



22.31 



6.68 



17.93 



6.42* 



6.02* 



6.98* 



11. 



29.05 



20.74 



23.25* 



22.96* 



21.32* 



24.73* 



12. 



32.36 



17.74 



29.13 



16.20* 



11.20 



12.99 



13. 



32. U 



15.63 



25.71 



13.99* 



12.36* 



14.34* 



14. 



40.30 



26.81 



40.30 



29.30* 



20.39* 



23.65* 



15. 



40.80 



18.89 



39.41 



19.31* 



15.95* 



18.50* 



16. 



41.12 



16.29 



34.04 



17.33* 



14.10* 



16.36* 



17. 



63.91 



16.18 



46.68 



22.11 



18.53* 



21.49 









INTERPRETER 3 







1 





1 . / o 



3 



1.40* 



1 22 



1 . 42* 



O 

 ^ • 



0.0/ 



1 . /o 





2.21 



07* 

 Z . U / 



AO 

 Z . rt*-' 



o 



o. 



4 . ol 



2.83 





2.70* 



Z . UZ 



Z , 



4, 



0.04 



C 1 A 



5. Id 





4.91* 



6 . /D 



4 . JO 



C 



1 A A 



1 . 44 



6 .04 





6.69* 



A 07 * 



D.I/ 



6. 



8.78 



6.00 





6.29* 



5.64* 



6.54* 



7. 



9.83 



8.06 





6.60* 



6.81* 



7.90* 



8. 



17.61 



8.98 





10.56* 



9.76* 



11.32 



9. 



20.30 



18.67 





16.28* 



13.44 



15.59* 



10. 



22.31 



6.68 





5.35* 



6.31* 



7.32* 



11. 



29.05 



20.74 





20.39* 



16.18* 



18.77* 



12. 



32.36 



17.74 





16.93* 



11.65 



13.51* 



13. 



32.44 



15.63 





19.02* 



19.07* 



22.12 



14. 



40.30 



26.81 





27.60* 



12.78 



14.82 



15. 



40.80 



18.89 





25.87 



16.48* 



19.12* 



16. 



41.12 



16.29 





20.77 



16.78* 



19.46* 



17. 



63.91 



16.18 





28.62 



22.50 



26. 10 



Total number of 

 estimates (*) falling 

 within ±25 percent 

 of measured shal- 

 low area 



16/34 



41/51 



35/51 



38/51 



■''Obtained from photos by dot -grid method. 



^ Based on soundings taken in field and dot count. 



^Method A was used by two interpreters only. 



21 



AFPS, Ogden, U»ah 



