Table 4. — A comparison of streamflow from 

 the East and West Branches of Chicken 

 Creek (water year 1966-1970) 



Unit of measurement 



East Branch 



West Branch 



Mean annual flow 







inches 



9.7 



18.7 



c.f.s. 



0.15 



0.47 



c.s.m. 



0.72 



1.23 



acre ft. 



111.8 



280.4 



Maximum annual flow 







acre ft. 





A AO 0^ 



Minimum annual flow 







acre ft. 



66.35 



177.83 



Maximum recorded flow 







c.f.s. 



4.67 



13.39 



Minimum recorded flow 







c.f.s. 



0.001 



0.001 



Figure 18. — Comparison of mean monthly 

 streamflow (1965-1970), East and West 

 Branches. 



watersheds by the prevaiHng southwest winter 

 winds. These winds deposit deep drifts on the 

 lee side of the ridges which form the south- 

 west boundary of the West Branch and at the 

 same time clear the snow from the windward 

 side of the high ridge, which forms the north 

 and east boundary of the East Branch. Sel- 

 dom is the snow depth greater than a few 

 inches on that high ridge during the winter, 

 but depth increases downslope in general re- 

 sponse to the height of the vegetation. The re- 

 distribution of snow increases the effective 

 depth of winter precipitation on the West 

 Branch and reduces the effective depth of 

 winter precipitation on the East Branch. Ttiis 

 hypothesis will be tested during the 

 1971-1972 winter. Forty permanent snow 

 measurement points have been established on 

 the two study watersheds. Snow depths and 

 density will be measured at each point after 

 major storms and again several davs later. 

 These measurements should help quantify the 

 redistribution of snow on the area. 



Calibration 



In all watershed studies, we must deter- 

 mine whether sufficient correlation exists be- 

 tween watersheds so that the expected change 

 in streamflow due to treatment can be detect- 

 ed at a reasonable confidence level. Regres- 

 sion equations for several different periods of 

 streamflow data from the East versus the West 

 Branches are presented in table 6. In these 

 analyses the West Branch was the dependent 

 variable. 



The R2 values are all high, indicating that 

 most of the variation in streamflow between 

 watersheds is accounted for in the regression. 

 The best correlation appears to be with the 5 

 years of annual flows measured by the present 

 gaging stations. When the 6 years of stream- 

 flow data measured at the "V" notch stations 

 are included in the regression, the R2 de- 

 creases. Individually, streamflow from the 

 two periods fit the respective regression lines 

 very nicely, but the two lines diverge. Perusal 

 of the data indicates that the problem is 

 caused by the lack of comparability of the 

 winter flow between the two time periods. 

 Winter flow was estimated during the time 



21 



