WHAT IS AN AQUIFER?
(Fig 1.Owned by: FloridaSpringsInstitute.org) Florida Natural Springs and Aquifers.
How Do Florida’s Aquifer Systems Form?
It takes a significant amount of rainwater to keep Florida’s fresh water above and below ground at normal levels. This means Florida’s rivers, lakes, ponds, springs, and aquifers systems, must be re-charged with fresh water yearly. With this in mind, the average annual rainfall in central Florida varies from 51 inches in drier years to over 70 inches in wetter years, which is almost 6 feet per year. This amount of rainfall comes year after year and can add up quickly. Where does all this water go you may ask?
Floridan and Biscayne Aquifer Systems
Florida has two major aquifer systems called the Floridan, and the Biscayne. “The Floridan Aquifer is the largest and deepest in the state. It stretches for 82,000 squ are miles beneath Florida and parts of Alabama, Georgia, and South Carolina.” (4) These two aquifer systems absorb about 50% (2) of Florida’s yearly rainfall totals and store all the water in earthen structures called aquifer systems.
How Does Water Move Through The Earth’s Surface?
Florida has a unique natural water movement system to move water above and below ground. This “system” consists of rivers, lakes, ponds, springs, aquifer systems, swamps, bogs, and sun-induced evaporation. Each and every one of the water resources mentioned above is essential to Florida’s natural water movement system. Here we see the “system” is greater than the sum of its parts. Another part of the “system” not mentioned so far is the longitudinal center of the Florida peninsula. It can rise some 200 feet (3) above sea level and produces head pressure to propagate water movement to the each coast of the peninsula.
Turn your attention to a particular part of the “system” described above called “aquifer systems.” Florida’s aquifers are a primary source of fresh water for most residents in Central Florida. Aquifer systems are composed of different types of earth containing shell, sand, and limestone, which is the case in Central Florida (1). These unique systems are made of sponge-like porous rock types consisting of, in this instance, limestone rock, sand, and clay. These materials allow water to move through them and form the boundary of the aquifer. Because of aquifers, Florida has natural surface springs that are like windows to underground aquifer systems or water tables.
Contained aquifer water is usually under pressure. This pressure allows water to rise to the surface in some instances and known as a natural surface spring. Natural springs filled with crystal clear aquifer water can reach thousands of feet (3) deep and miles in length, all underground except a relatively small opening at the earth surface.
As described above, an aquifer is a large underground cavern of porous materials like sand, clay, and limestone rock. Rainfall seeps through the different material in layers of the earth. This naturally filters the water that enters the aquifer through a process called “percolation.”
The land surface shape determines how much rainfall seeps in an aquifer. Lowlands hold the water as a reservoir then gravity can take over to feed water back to the aquifers. As much as 50 percent of Florida’s average rainfall each year will perpetually recharge the aquifers (2).
Beautiful Karst Springs In Central Florida
“Karst” (1) springs are “artesian” springs and discharge tremendous amounts of crystal clear aquifer water daily. The hydraulic pressures created underground force aquifer water to the surface through cracks, crevices, and will bubble up through the sand as well. This type of natural spring is what most people think of in Florida because these are the largest, easiest to find, and are great “Old Florida” tourist destinations.
Florida’s natural springs, river, and lakes provide residents and visitors year round access to boating, diving, snorkeling, fishing, swimming, and relaxation. The natural springs in Florida are ”re-charged” by the average yearly rainfall and absorbed by sponge-like porous earth materials that also filter and clean vast amounts of water.
1. Florida's Aquifers, FloridasWaterdotcom
2. Florida's Water Then and Now, fcit.usf.edu/florida/lessons/water/
3. Springs, Sinkholes, Florida Aquifer, FloridaSpringsdotcom
4. The Floridan Aquifer | WaterVenturedotcom