REPORT OF INVESTIGATIONS No. 42


.n wells located generally along the eastern and southern bounda-
ries and in the interior. Continuous records of water-level fluctua-
tions and rainfall were collected at each well site. The data were an-
alyzed to select short periods during which all of the rainfall was
assumed to reach the water table. One or two-day periods were se-
lected when (1) antecedent conditions compensated for moisture
requirements of the unsaturated material above the water table;
(2) the water table was far enough below the ground to store all
the rainfall and none left as runoff; and (3) the rainfall was of
short duration, high intensity, and widespread. The rise in the wa-
ter table is directly proportional to the depth of rainfall. The spe-
cific yield of the aquifer therefore is inversely proportional to the
ratio of rise in the water table in inches to the depth of rainfall in
inches.

 EASTERN-SOUTHERN RIDGE AREA


 Well 810-144-2 (Nonortesion aquifer)
(010


 5 Average slope=
 5 4.5
 Specific yield 22.2 %


 0 --
 0 5 10 15 20
 RISE IN WATER LEVEL IN INCHES
 INTERIOR OF THE

 Well 813-149-2 (Nonartesion aquifer)



S5
 SAverage slope =-
 Specific yield 12 5% --


 0 5 10 15- 20
 RISE IN WATER LEVEL IN INCHES


 Well 822-138-2(Nonarlesion aquifer)
 10




 z 4.7
 4 1'. Average slope=
 a: o ^ Specific yield 47%
 0 5 10 15 20
 RISE IN WATER LEVEL IN INCHES
GREEN SWAMP AREA


 Well 832-154-2 (Nonortesian

10
2:


z
J 5-

vi
'2


aquifer)


 Average slope 10
Specific yield IB% __ .--
 0'


0 5 10 15 21
 RISE IN WATER LEVEL IN INCHES


 WESTERN AREA

 Well 821-202-3 (Unconfined Floridan aquifer)

 EXPLANATION
 Plots of change in water level ofter selected
5Average lope periods of rainfall recorded at same well.
 Average slope =-
 Specific yield 14.3% _, ----- Line represents the overage change in water level.

 S..._.----. -- Specific yield = average slope X 100
 0 5 10 1 20
 RISE IN WATER LEVEL IN INCHES

 SFigure 30. Graphical determination of specific yield.