STREAMFIOW 



Gaging Stations 



Temporary 90° "V" notch weirs were oper- 

 ated near the present gage locations from 

 1952 to 1958. In 1965 a 3-foot "H" type 

 flume with concrete block stilling well house 

 was installed at the mouth of each watershed. 

 Streamflow is being recorded continuously on 

 Fisher-Porter analog-to-digital punch tape re- 

 corders at 15-minute intervals from April 

 through October, and 30-minute intervals dur- 

 ing the remainder of the year. The flumes 

 have a rated head capacity of 0.02 to 2.9 feet 

 or a maximum discharge capacity of 30 c.f.s. 

 A heating system was developed for these sta- 

 tions to permit measurement of winter flows 

 (Doty and Johnston 1967). The system con- 

 sists of plywood flume covers, a 12,000 B.t.u. 

 infrared heater mounted beneath the cover, 

 and a small floating heater in the stilling well. 

 The system has proven very effective in elim- 

 inating ice formation at the stations. 



Streamflow 



The annual streamflows from the East and 

 West Branches of Chicken Creek are presented 



o' ' ' ' ' ' — ' ' — ' 'I ' ' z 



1965-1966 1966-1967 1967 1968 1968 1969 1969 1970 2 



< 



WATER YEAR 



Figure 17. — Comparison of annual stream- 

 flow and annual precipitation 

 (1965-1970), East and West Branches. 



in figure 17 and compared to annual precipi- 

 tation. Mean annual flow from the West 

 Branch is slightly more than twice that of the 

 East Branch for the 5-year period, but these 

 watersheds display rather marked fluctuations 

 in annual flow in response to relatively small 

 changes in annual precipitation. The West 

 Branch also produces 36 percent more water 

 per acre than the East Branch (table 4). 



The distribution of streamflows through- 

 out the year (timing) is often more important 

 than the total of these flows, especially when 

 downstream storage facilities are inadequate 

 or lacking. Mean monthly streamflows (table 

 8, Appendix) are compared in figure 18. The 

 flows from both watersheds are very low for 

 about 7 months of the year, usually from July 

 through February. About 88 percent of the 

 total flow from the two watersheds occurs 

 during 3 months, April, May, and June in re- 

 sponse to snowmelt. Neither watershed shows 

 much response to the general increase in rain- 

 fall during the late summer and early fall (fig. 

 3) indicating that these rains serve to recharge 

 the depleted soil mantle and do not immedi- 

 ately affect streamflow. 



Annual streamflow was expressed as a per- 

 cent of annual precipitation (table 5). In gen- 

 eral, the higher the annual precipitation, the 

 greater the percent yielded, and once again 

 the yield from the West Branch is about twice 

 that of the East Branch. The difference in 

 both per acre and percent yields from the two 

 areas may be explained by noting the topo- 

 graphical dissimilarity of the two areas with 

 respect to the distribution and redistribution 

 of precipitation. We believe that the East 

 Branch does not effectively catch and hold 

 the precipitation that falls on it, especially 

 along the high ridge that forms the northwest 

 boundary. First, it is generally accepted that 

 rainfall diminishes near the crest of exposed 

 ridges; this would tend to reduce the amount 

 of rainfall intercepted by the watershed. Sec- 

 ondly, snowfall is redistributed on both 



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