The Journey of water
To understand Florida’s springs and their importance as natural resources, we must first understand the water cycle and aquifer that sustains them
Contrary to popular belief, Florida’s springs are not the source of freshwater; they are but one step on water’s long journey through what is known as the Floridan Aquifer, our underground water source. Learn about the water cycle and the flow of water through the aquifer to gain a better understanding of Florida’s springs. Also, learn more about how humans impact the quality and quantity of water in the aquifer and ultimately in the springs.
WATER CYCLES AROUND
The journey of water begins in the sky, where the state’s abundant rainfall recharges the Floridan aquifer, our underground water source. Read below to learn about the water cycle and how it contributes to spring formation.
Rainfall is a function of various atmospheric and physical factors, and the most important of these are gravity and humidity. As the tiny water droplets within a cloud merge together into larger, heavier drops, they eventually overwhelm the relative level of atmospheric humidity that keeps them airborne. Relative humidity is a measurement of the amount of water the air can hold at a given temperature. Scientists have recently determined that once these drops reach a diameter of twenty millimeters, rain will begin to fall. Every day, over 150 billion gallons of rain falls in Florida, more than any other state in the nation except Louisiana.
Evaporation and Condensation
Water’s journey through the water cycle begins with a process called evaporation whereby water stored in surface bodies of water like lakes, rivers and the ocean is converted into water vapor by the heat of the sun. Convection then draws this warmer, wetter air upwards where it comes into contact with cooler, high atmospheric air and eventually condenses back into tiny water droplets. Collectively, these tiny droplets are called clouds.
In addition to evaporation, a significant percentage of the water is released into the atmosphere by trees and plants in a process called transpiration. In order to facilitate photosynthesis, plants absorb water from the soil through their roots, a process that can also clean water by filtering out nutrients and pollution. They then transpire this water back into the atmosphere through their leaves and stems. About 70 percent of all rainfall returns to the atmosphere in the form of evaporation and transpiration.
Rainfall that is not absorbed directly into the soil, through the roots and leaves of plants, or accumulated into existing bodies of water such as lakes or rivers is called surface, or stormwater runoff. In areas where the underlying geologic formation is impervious to water, as in the case of clay, runoff is a natural process, directing water in sheet flow, into lakes, rivers, wetlands, and the ocean. In Florida, where loose sandy soils and porous limestone bedrock are common, rainfall that reaches the surface of the earth usually soaks directly into the ground.
Rainfall seeps underground through a process called percolation, whereby water travels downwards through the tiny spaces between rocks and soil particles, and within the “Swiss cheese” structure of the limestone. The water eventually saturates the underlying limestone in much the same way water fills the tiny holes of a sponge. It is this process of percolation that allows Florida’s abundant rainfall to replenish the immense volumes of water flowing from the springs.
Rain Falls Again
Though the first step of water’s journey to the springs begins in the sky, the water cycle itself is a never-ending process, and no single step is more important than any other. Evaporation, transpiration, condensation, rainfall, run-off, and percolation all play a critical part in ensuring that water is consistently available for both natural processes and human use.