extrapolation of data beyond the highest calibration flow is a less desirable 

 option since our main interest is to derive minimum flow recommendations. 

 Remember, the stage-discharge rating curve generally flattens out at extremely 

 high (above bankfull) and extremely low flows. At these flows, the predicted 

 stages from the measured rating curve are inaccurate and will lead to 

 inaccurate hydraulic predictions. 



Use the following guidelines when selecting flows of interest (Bovee and 

 M: lhous, ] 978) : 



1. Two point stage-discharge rating curve 



Hydraulic predictions should not be made for flows which are less than 

 0.77 times the minimum measured flow, nor for flows higher than 1.3 times 

 the maximum measured flow. 



2 - Three point (or greater) stage-discharge rating curve 



Hydraulic predictions should not be made for flows which are less than 

 0.4 times the minimum measured flow, nor for flows higher than 2.5 times 

 the maximum measured flow. 



WETP Data Output 



The output for the input example in Appendix B is given in Appendix C 

 Carefully examine this output. 



When reviewing your outputs, consider the following: 

 1 . Errors 



Carefully check the profile and stage-discharge data on the printouts for 

 errors. The keypunch operators occasionally make errors, even though 

 they carefully proof the data files. The vast maloritv of errors, 

 however, are the result of format and recording errors on the coding 

 sheets. If corrections are needed, mark all changes on the coding sheets 

 in red ink or pencil and return to Fred Nelson so the file can be 

 corrected and your data rerun. 



2. Error messages 



The vast majority of error messages that occasionally appear on the 



printouts are a result of undetected format errors on the coding sheets 



These are easily corrected and the file rerun before the printout is sent 

 to the cooperator. 



An error message will appear when predictions are requested for flows of 

 Interest having stages higher than the highest elevations in the 



6-2 



