HYDROLOGY OF GREEN SWAMP AREA IN
 CENTRAL FLORIDA
 By
 R. W. Pride, F. W. Meyer, and R. N. Cherry


 ABSTRACT

 Green Swamp is an area of about 870 square miles of swampy
flatlands and sandy ridges near the center of the Florida Peninsula.
The elevation of the land surface ranges from about 200 feet above
mean sea level in the eastern part to about 75 feet in the western
part. The Withlacoochee River drains two-thirds of the area. The
Little Withlacoochee River, the headwaters of the Oklawaha River,
the Hillsborough River, the headwaters of the Kissimmee River,
and the headwaters of Peace River drain the remaining area. The
surface is mantled with a varying thickness of sand and clay which
comprises the nonartesian aquifer. Porous marine limestones
comprising the Floridan aquifer underlie and drain the subsurface.
The Floridan aquifer crops out in the western part of the area and
occurs at depths ranging from 50 to more than 200 feet in the
eastern part. The mineral content of both surface and ground
water does not impair the usability of the water for most purposes.
However, surface water is generally highly colored and acidic, and
ground water is hard and generally contains objectionable amounts
of iron.
 Hydrologic data were collected during the period, July 1, 1958,
 to June 30, 1962, for making quantitative and qualitative analyses
 of the hydrologic budget and for determining the significance of
 the hydrology of the Green Swamp area with respect to central
 Florida.
 Extremely high and unusually low annual rainfalls were
 recorded during the period of investigation. The factors of the
 water budget for each of the 3 complete years of record, 1959-1961,
 show that average rainfall on the area ranged from 70.9 to 34.7
 inches; surface runoff ranged from 31.1 to 2.3 inches; ground-water
 outflow ranged from 1.8 to 2.2 inches; and water derived from
 change in storage ranged from insignificant amounts in 1959 and
 1960 to about 4.3 inches in 1961. Evapotranspiration losses, which
 were the residuals in the water-budget equation, ranged from 39.1