66 FLORIDA GEOLOGICAL SURVEY

water table) is free to rise and fall. Artesian aquifers are saturated,
confined or semi-confined, and their water surface is not free to
rise and fall. The water in an artesian aquifer is under pressure
(greater than atmospheric) which causes it to rise above the top
of the aquifer. The level to which water will rise in tightly cased
wells, penetrating an artesian aquifer, is called the piezometric
surface.








 I ,
 ^rrz: ~ ~ ~ --- -_-::_:--z= ::


 i \
tL




M. _
.. .---.-- ---- -- --- -


 i -_ -

 r T ri'~~'^ ~~~ ~ ~ -
 S|Horse Creek at Davenport


 j Pony Creek near Polk City _____

c Qo8|-- --- - --
4 ___- -----
 C 51 -- - -- -- --


 0 OS 005 2 a5 I Z S 10 20 30 40 50 60 T 80 90 95 98 99 995 999 99.91
 PERCENT OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED
Figure 22. Flow-duration curves for Horse Creek at Davenport and Pony
 Creek near Polk City, 1960-62.