STATION I 



STATION II 



STATION III 



50 



^^^^1 Veloc I ty m.p.s. 



Direction "/(, of time 



■^r Downstream direction 



RESERVOIR CONDITION 

 Period July 2 to August 25 



Pool status Full pool 



Pool level Full pool 



Inflow 316 cm s (daily average) 



Spill discharge None 

 Total discharge 312 cms. (daily average) 



Figure 14. — Direction (percentage of time, indicated by scale between center and upper margin of each figure) and 

 average vel(x;ity (m.p.s. scale between center and lower margin) of currents recorded at 3-m. depth in Brownlee 

 Reservoir during full pool with no spill, July 2 to August 25, 1964. Direction reads toward point of wedge. 



(station 20). Velocities and directions of .surface 

 currents seemed to depend primarily upon veloc- 

 ities and directions of the wind. 



Effect of wind on currents. — The wind near sta- 

 tion 14, measured at a set time each day, showed 

 a trend. In contrast, the currents were recorded 24 

 hours. In future studies of this type, we recommend 

 that wind direction and velocity be measured con- 

 tinuously along with direction and velocity of sur- 

 face water current at each station so that they can 

 be directly correlated. 



Wind direction and velocity had a considerable 

 influence on surface currents. The wind was pre- 

 dominantly northei-ly or southerly, rarely easterly 

 or westerly (tables 4 and 5). The reservoir flows 

 generally from south to north; thus, the primary 



effect of wind was either to increase or diminish 

 the velocity of the prevailing surface currents. A 

 wind of high velocity and relatively long duration 

 was required to reverse a pre\ailing surface cur- 

 rent of more than 0.0.3 m.p.s. 



Wind apparently had the least effect near the 

 head of the reservoir, where the inflow had com- 

 paratively high velocity during all reservoir stages 

 except at full pool with low inflow. Wind had a 

 decided effect on the lower and middle sections of 

 the reservoir (stations I and II), where velocities 

 rarely exceeded 0.25 f.p.s. (0.08 m.p.s.). Effects 

 were significant at these areas during all reservoir 

 stages except at maximum drawdown. Instanta- 

 neous sampling indicated that wind could affect 

 measurable currents to a depth of 8 m. 



324 



U.S. FISH AND WILDLIFE SERVICE 



