Hydrogeology

Ground water is the largest and most readily available source of potable water in Florida. Hydrogeology is the study of ground water with emphasis given to its chemistry, modes of movement, and relation to the geologic environment. Hydrogeology integrates geology, hydrology, chemistry, physics, mathematics, biology, and engineering to understand the occurrence and movement of water in the complex subsurface environment.

Water-bearing sedimentary rocks in Florida can generally be divided into two types: siliciclastics (sands, silts, clays) or carbonates (limestone and dolostone). All of these rocks, no matter how "hard" or solid they appear, contain some voids or pores, which may contain water. Two properties that are common to all these rocks, and which control the movement of their ground water, are porosity and permeability. Porosity and permeability are intimately related. Porosity refers to the pores themselves, while permeability is a measure of a rock's ability to allow fluids to move through its pores. For a rock to be permeable, its pores must be interconnected so that water can move freely.

Aquifers are subsurface zones of rocks that yield water in sufficient quantities to be economically useful for society's activities. Aquifers are classified as either unconfined, semi-confined, or confined, depending on the physical conditions under which the water is contained in an aquifer's rocks. Florida has all three types of aquifers in various combinations throughout the state. The Floridan aquifer system (FAS), which underlies all of Florida, is the main source of potable ground water for much of the state. However, in the extreme western panhandle and in south Florida the FAS is either too deep or contains water of poor quality.