FLORIDA GEOLOGICAL SURVEY


            THE HYDROLOGIC ENVIRONMENT

                   GENERAL STATEMENT

   Water in the natural state continually moves due to many forces acting upon it. Gravity acts on water in streams and underground to keep it moving downward toward the level of the ocean. The sun and wind evaporate water from open water bodies and plants'transpire water to the atmosphere. Gravity again moves the water earthward when the atmospheric moisture meets conditions favorable for rain. This never ending'movement of water is known as the hydrologgic cycle.
   The water resources of any area depend upon this hydrologic cycle. When the rate of water movement out of an area exceeds the rate of water movement into the area, water shortages Will develop. Water shortages may also develop if the quality of water is significantly altered within its natural environment to make it unfit for its intended use. Variations in the rate of movement in any phase of the hydrologic cycle, such as rainfall, may also affect an area by resulting in floods and droughts. Proper development of the water resources of an area requires a thorough knowledge of water movement and the factors controlling it. This knowledge will enable the best prediction of where to obtain water and what provisions are required to control water movement.
   In general, the system through which water moves in the Econfina Creek basin is similar to most river basins in Florida. Like most other basins, (1) rainfall is the source of all the water even though some falls outside the basin and moves into the basin underground;
 (2) the surface materials are highly porous, unconsolidated sands;
 (3) the basin is underlain by the artesian Floridan aquifer; and
 (4) water leaves the basin by streamflow, evaporation, transpiration, underground flow to the ocean and other basins, and by consumptive use.

             PHYSICAL MAKEUP OF THE BASIN

    Four physiographic divisions within the basin affect the surface drainage and the-water storage. These are the sand hills, sinks and lakes, the flat-woods forest, and the coastal beach sand dunes and wave-cut bluffs, shown in figure 2. The physiographic divisions have developed on a series of stair-step marine terraces which were carved into the surface sands during the ice age by the successive levels of