86 REPORT OF INVESTIGATIONS No. 50
RECHARGE
Most natural recharge to the nonartesian aquifer in Orange County comes from rain within or near the county. Some recharge comes from upward leakage of water from the artesian aquifer in areas where the piezometric surface is above the water table and from seepage from streams in areas where the streams are higher than the surrounding water table.
Artificial recharge to the nonartesian aquifer occurs by infiltration of water applied for irrigation, discharge from septic tanks, and by discharge from flowing wells.
Most of Orange County is blanketed with permeable sand which allows rain to infiltrate rapidly. In much of the eastern and southern parts of the county, where the land is flat and the water table is near the surface, the overlying surfaces and is quickly saturated during the rainy season; and the excess collects in swamps and sloughs or runs off in streams and rivers. In much of the western part of the county, the water table is far below the surface except in depressions. The surface sand can absorb rainfall at a rate of as much as 3.5 inches per hour with little or no direct surface runoff (Powell and Lewis, open-file report), and the large volume of sand above the water table holds large quantities of water which percolates slowly to the water table.
DISCHARGE
Discharge from the nonartesian aquifer in Orange County is by evapotranspiration, seepage into surface-water bodies, downward leakage to underlying aquifer, pumpage, and seepage into neighboring counties.
Ground water is removed from the zone of saturation and from the capillary fringe by the roots of plants and is given off to the atmosphere by transpiration. The depth to which plant roots penetrate depends on the type of plant and the soil, and ranges from a few inches to 50 feet or more for certain types of desert plants. In Orange County the maximum depth of tree roots is about 15 feet whereas the water table in most of the county is less than 15 feet below the surface; therefore, discharge of nonartesian ground water to the atmosphere by transpiration is appreciable.
Where the water table is near the land surface, ground water moves upward by capillary action through the small pores in the soil to the surface and evaporates. The rate of evaporation varies