STATION I MILE 1 



STATION 



STATION II MILE 24 



^^^^ Veloci ty m.p.s. 



Direction % of time 

 ■^^ Downstream direction 



RESERVOIR CONDITION 



Period May 29, 1964 



Pool status Filling 



Pool level Minus 11.3m. 



Inflow 643 cm. s. 



Spill discharge 



Total discharge 273 cm. s. 



Figure 11. — Continued 



mediately before spilling (fig. 12). Spilling be- 

 gan again on June 9 and by June 12 had reached 

 about 708 c.m.s. and through June 13-26 averaged 

 1,013 c.m.s. This spilling caused currents at sta- 

 tion I to be oriented downstream; currents were 

 downstream 93 percent of the time. The percentage 

 of zero readings (66 percent) was high at mid- 

 reservoir (station II). Currents at the upper end 

 of the reservoir were oriented downstream 49 per- 

 cent of the time ; water velocities here ranged from 

 0.07 to 0.18 m.p.s. Vertical and counter currents 

 undoubtedly accounted for the lack of downstream 

 orientation at the upstream end of the reservoir. 

 Thus, for the period of high inflow and iiigh spill 

 at full pool, currents in the lower reservoir were 

 well oriented in a downstream direction, but the 

 discharge had little influence on currents at mid- 

 reservoir. Velocities increased in the upper reser- 



voir, but downstream orientation of the currents 

 was not visibly stronger. 



Full pool witJiouf spin. — The reservoir re- 

 mained at full pool without spill from July 2 to 

 August 25, 1964. The mean daily inflow was 316.2 

 m.p.s.; the average outflow was 312.3 m.p.s. The 

 reservoir was thermally stratified, and the ther- 

 mocline was well defined. Downsti-eam movement 

 of surface water was negligible^ — weak upstream 

 and downstream currents were nearly equal. Cur- 

 rent readings of zero were common at midreservoir 

 (fig. 14). 



Instantaneous Current Measurements 



Instantaneous measurements of current direc- 

 tion and velocity at the limnological stations under 

 the five reservoir conditions are presented. We rea- 

 soned that some knowledge of subsurface currents 

 could be gained from these measurements and that 



LIMNOLOGY OF BROWNLEE RESERVOIR 



321 



