Florida's water management challenges and aquifer systems

Florida's Water

Developing Water Issues in Florida

The Hydrologic Cycle

The hydrologic cycle is the process by which water moves through the environment. Surface water evaporates or transpires from surface collections and plants to condense in the atmosphere as clouds. Those clouds release precipitation that falls back to the Earth. Some of that water percolates through the surface and charges underground deposits of water. The hydrologic cycle consists of the passage of water through the environment in different states in response to environmental conditions. The hydrologic cycle includes processes such as storage as ice/snow, precipitation, infiltration, ground water storage, ocean storage, evaporation, condensation, evapo-transpiration, surface runoff, springs, and sublimation (Cervone, "Florida Aquifers"; "Hydrologic Cycle"; Perlman).

The hydrologic cycle is fundamental for the overall health of the environment and the quality of the Earth's water supplies. The constant movement of water through different states -- solid, liquid, gas -- and through different parts of the planet repeatedly recharge and refresh the quality of the planet's water supplies. Without the hydrologic cycle, water would quickly become stagnant, polluted and unusable for life. The importance of the hydrologic cycle cannot easily be understated.

Issues in Water Management

Because of the action of the hydrologic cycle, we can conclude that water is a renewable resource. Though there's probably not significantly more or less water on Earth than throughout the geological past, the quality of the water is constantly refreshed through the hydrologic cycle ("Hydrologic Cycle"). Despite the fact that no new sources of water are produced in a given year, the hydrologic cycle purifies that water as it passes through the environment and through different states. For instance, consider the passage of water from the surface and into subsurface groundwater deposits. One mechanism by which this can occur is via a disappearing stream. A disappearing stream occurs when ground or subsurface water erodes soluble rock and permits surface water to percolate into underground channels. This can result in disappearing streams since the surface rock no longer acts as a confining barrier (Shaw).

Rainfall that would have charged surface streams can thus pass into the earth and enter into subsurface aquifers, which are large underground deposits of water contained by confining barriers of insoluble rock. The passage of surface water into these aquifers provides a basic explanation for how these aquifers are recharged by rainfall and surface water (Cervone, "Florida Aquifers"). Many aquifers are formed in limestone deposits because this mineral is water-soluble. The result is subsurface features known as Karst topography, a series of caves and channels that collect and store groundwater. Unfortunately, because limestone -- and some other types of rock -- is relatively easily eroded by water, the tops of these caverns and channels can sometimes be eroded to the point that they collapse. The result is a sinkhole, which forms when a subsurface cavern is exposed by the action of water (Rosenberg; Shaw).

The Situation and Circumstances in Florida consideration of the abovementioned geological features is especially pertinent to a discussion of the water resources of Florida. The geological composition of the Floridan bedrock is composed significantly of limestone. Forty million years ago, the region that is now Florida was at the bottom of an ocean. The subsea plateau that would eventually emerge as the Florida peninsula was a marine shelf that collected the deposited remains of sea creatures, especially coral. Over time, these deposits formed limestone bedrock that covered the entire peninsula. Compaction and cementation processes acted on these deposits in varying ways to form a limestone substrate underneath Florida with variable degrees of permeability and solubility (Cervone, "Florida Geology"; "Carbonate-Rock Aquifers").

In other words, the geological nature of the Floridan aquifer system is highly variable and consists of significant deposits of limestone. This means that permeability and erosion of soluble rock makes surface infiltration of the subsurface aquifers a consideration in managing the integrity of the water supply. In the natural hydrologic cycle, recharging aquifers with surface water is an expected and useful process. However, when we add a human factor to the equation, surface pollutants and runoff from human activities can quickly pollute aquifers that provide fresh water for the entire region. Because the major aquifers underneath Florida stretch for hundreds or thousands of miles, the impact of localized surface pollution can affect the quality of the water over a broad area.

One of the most significant factors to consider in terms of human impact is population growth and population density. The total population for the state in 2006 was more than 18 million, up from 15.9 million just six years earlier. When we compare population growth over the past forty years, we see a surprising leap from only 4.95 million people in 1960 ("Fact Sheet"; Forstall). Much of that population growth, which more than tripled over the last forty years, has occurred in urban areas throughout Florida such as Broward County, Dade County, Palm Beach County, and Pinellas County (Forstall). As the population in the state continues to grow so rapidly and concentrates itself in urban areas, we can see two immediate effects on the integrity of the subsurface water supplies. First, more people means that there will be an increased demand for water resources that are limited, even if they are quite large. Second, more people also means for opportunities for surface pollutants from human activities to percolate into those aquifers and damage the integrity of the hydrologic cycle. Thus, at the same time we witness an increased demand for fresh water in Florida we are also faced with the prospect that what water there is will be too polluted to use.

Glossary

The glossary provided contains key definitions for some of the terms important in the study of water management issues both in Florida and throughout the world. This listing is meant to be a reference for some of the terms most relevant to this study, but that also have wider usage.

Aquifer: underground water bearing rock formations; major Florida aquifers include the Biscayne, sand and gravel, Chokoloskee, and Floridan (Cervone, "Florida Aquifers")

Confined vs. Unconfined: the difference between layers of rock that are permeable and impermeable, and thus more or less able to contain subsurface water ("Floridan Aquifer")

Disappearing Streams: disappearing streams can be products of Karst hydrology; as soluble rock dissolves, surface stream increasingly diverted underground (Shaw)

Karst Topography: groupings of underground caves of rock formations created by the action of underground water on limestone deposits (Rosenberg)

Recharge Zone: places that recharge subsurface aquifers through the input of rainfall (Cervone, "Florida Aquifers")

Sinkhole: form when underground voids collapse after the rock has been removed by dissolution (Shaw)

Wastewater Treatment: process by which wastewater is reconditions for reuse ("Domestic Wastewater")

Water Conservation: methods to reduce consumption of water resources (Best Management 1)