82 REPORT OF INVESTIGATIONS No. 50
of type 2 flooding, the county often suffers soil moisture deficiencies at high-ground locations while lakes remain flooded in other areas.
The bed slopes of the streams that drain Orange County are so slight that velocities are not sufficient to cause appreciable erosion of the vegetation-filled channels. Consequently, the channels have not cut to depths that are below the water table when it is at even moderately low levels. Because of this most of the streams either cease flowing or recede to extremely low flow after only about 90 days of drought. To date, problems associated with low flow have been minimal in the country; but as the population and industrial complex expand, the need to dispose of wastes by way of streams may become more pressing. Because streamflow is small or nonexistent a large part of the time, streams cannot be used to transport wastes without becoming excessively polluted unless their base flows are improved or augmented. The base flow of a stream can be increased by deepening its channel to intercept the water table during droughts and cutting lateral ditches from the channel to increase the length of channel exposed to seepage. This would, of course, lower the water table adjacent to the channel and lateral ditches, but it would also improve the conveyance of the channel and the increased channel capacity would tend to reduce the height of flood crests. The flow of the streams could be augmented with water pumped from the artesian aquifer.
GROUND WATER
Ground water is the subsurface water in the zone of saturation
-the zone in which all the openings of the soil or rock are completely filled with water. The source of all natural fresh ground water is precipitation which in Florida is almost entirely rain.
Ground water in Orange County occurs under nonartesian and artesian conditions. Nonartesian conditions occur when the upper surface of the zone of saturation (the water table) is not confined and, accordingly, is free to rise and fall directly in response to variation in rainfall and discharge. Artesian conditions occur where the water is confined and rises in wells above the point at which it is first penetrated.
NONARTESIAN AQUIFER
The nonartesian aquifer extends over most of the county and is composed mainly of quartz sand with varying amount of clay,