70 REPORT OF INVESTIGATIONS NO. 50
average flow at this station is the same as that at Econlockhatchee River near Chuluota (station 19), yet the peak flow is less than one-fifth that at station 19 and the minimum flow about 16 times that at station 19. At station 46, the maximum flow is only 20 times as great as the minimum flow while at station 19, the maximum flow exceeds the minimum flow by more than 1,600 times. This great difference in variability is due to the fact that about one-third of the rain that falls on Wekiva River basin and nearby areas seeps downward into the artesian aquifer where it is stored until released slowly through many springs whereas little of the rain that falls on Econlockhatchee seeps into the artesian aquifer but instead remains on or near the surface from where about one-fourth of it runs off very rapidly. Figure 33 gives low-flow frequency curves for Wekiva River.
500 -- .....
365 days Average flow: 275 cfs /273 days
400 183 days
S120 days LOW-FLOW FREQUENCY d 60 days Example: For a 10-year recurrence 30 days interval the I-day minimum flow is
cd.
200-
1.0 1 ~ 1 5 234ys7,0-,0,
K P
15 days/-/" "--.
7 days/- -I dayz
t00 - - 
1.01 1.1 1.2 1.5 2 3 4 5 7 10 20 30 Recurrence interval in years
Figure 33. Low-flow frequencies for Wekiva River near Sanford.