116 REPORT OF INVESTIGATIONS No. 50
dominated by well to excessively well-drained soils; Group II, areas dominated by moderately well-drained soils; Group III, areas dominated by somewhat poorly drained soils; and Group IV, areas dominated by poorly to very poorly drained soils.
Because water that drains downward from the surficial soil must go either into the underlying artesian aquifer or seep into nearby streams, soil types, when used in conjunction with stream-flow patterns, give a good indication of the relative effectiveness for recharge of the different areas. Figure 54 shows
(1) the extent of the possible recharge area for Orange County,
(2) the relative rate of stream flow by basins, (3) the relative effectiveness of various parts of the recharge areas based on soil types, and (4) areas from which there is no surface outflow. The figure shows that most of the recharge to the Floridan aquifer takes place in the highlands of western Orange County and adjacent areas of Lake and Polk counties. Much of this highlands area is closed basin sinkhole topography covered by thick permeable sand that rapidly absorbs rainfall. The water in the sand can then seep through the semi-permeable beds overlying the limestone and recharge the aquifer. The sand hills act as temporary storage areas that prevent surface runoff and reduce evapotranspiration. The areas from which there is no surface runoff are outlined in Figure 54. In much of the remaining area that is dominated by excessively well-drained soils, the surface runoff is probably very small.
Evapotranspiration is probably actually less in the rolling highlands than in the Econlockhatchee basin area because of the greater average depth to the water table and the relative absence of swamps which have very high evapotranspiration rates. No attempts have been made to evaluate this factor; and in the above discussion it was assumed that evapotranspiration is uniform throughout the county.
The prime recharge areas of the Floridan aquifer in Orange County are not sharply defined and all gradations exist between very effective and very ineffective areas. Figure 54 is intended to show the general area that is most effective in recharging the Floridan aquifer. Some recharge occurs wherever the water table is above the piezometric surface.
DISCHARGE AREAS
Discharge of ground water from the Floridan aquifer in Orange County is by (1) outflow into northern Lake County, into Seminole