Aquifers deep under our feet hold life. This is a stark reality for many millions of Earth's inhabitants, because an aquifer is "a water-bearing stratum of permeable rock, sand, or gravel." [Merriam-Webster, 2009] For untold millions, the water "under the ground" may be the only accessible supply available within hundreds of miles. The aquifer's importance rivals that of farmers, power plants, and inoculation against deadly diseases.
If one were to ask most of the people on the street of any major city in the world where they get their drinking water, they would be mystified. People who are not engaged in civil engineering or disaster planning usually have other things on their minds, and the water supply, of course, is "guaranteed," right? It will always be there, and plenty will be available for drinking, for washing the car, and for watering three acres of lawn. But will it be, really?
"There are two types of aquifers: replenishable and nonreplenishable (or fossil) aquifers. Most of the aquifers in India and the shallow aquifer under the North China Plain are replenishable. When these are depleted, the maximum rate of pumping is automatically reduced to the rate of recharge." [Encyclopedia of Earth, 2009] Our focus here is on that word "depleted." It means that our assured supply of this life-giving fluid is neither guaranteed nor secure. There is a finite supply of water to be pumped from under the ground, and only the shallow reservoirs are replenishable. In other words, both rainfall supply and climate change are factors in whether the shallow supplies of water continue to be available. What can we learn about the deep pools?
The fossil aquifers now contain all of the water they will ever hold. Water was deposited there at some time in the distant past, and then either the supply or access to the pools was cut off, meaning that the store of deep water reached its highest reserve. From the time deep reserves are first breached and their stores of water are pumped to the surface, fossil pools decline in size until they eventually give out. This concerns us most if we have no other easily-accessible supply of water when the reservoirs are empty. This means, at the very least, great hardship and expense to maintain life and/or agriculture. At worst, the end of these water supplies means death even for technically proficient human users.
An example of a deep aquifer is found under the central part of the United States. It has been in use since World War II. "The Ogallala Aquifer underlies approximately 225,000 square miles in the Great Plains region, particularly in the High Plains of Texas, New Mexico, Oklahoma, Kansas, Colorado, and Nebraska. The depth of the aquifer from the surface of the land, its reate of natural thickness, vary from region to region. The aquifer has long been a major source of water for agricultural, municipal, and industrial development." ["The Ogallala Aquifer Depletion," 2009]
History and Water
In the 1930s, farming practices, water shortages, and climate combined to drive many people from their farms in the middle of the U.S. Desertification, a term meaning simply the death of most vegetation and the area's capacity to support water-abundant activities, seemed likely to take hold in what has been termed the nation's "breadbasket," and many thousands of citizens of middle-America states had to move. This move was chronicled in the 1940 movie "The Grapes of Wrath." Though fictional, this film showed the hardship that lack of water can quickly cause to human populations, along with the extreme means some in those groups will exercise in order to survive.
There are more recent examples of the troubles to be experienced when aquifers are absent or insufficient to the task of supporting a large population. Study the troubles of cities located in arid states, or cities with huge concentrations of population. Two perfect examples would be Tucson, Arizona, and Los Angeles, California. For the importance of [local] aquifers, note where each city actually acquires its water (hint: it is neither Arizona nor California). One important form of trouble occurs when judicial means are used to determine how much of another region's water will be used by a local region.
Aquifers ideally deliver life to the populations living near or above them. How long they serve this purpose may depend, to a very great extent, on our stewardship of their reserves.
Aquifer. (2009). In Merriam-Webster Online Dictionary, accessed 1325 hours, 3 February 2009. <http://www.merriam-webster.com/dictionary/aquifer;
"Aquifer depletion," from Encyclopedia of Earth, accessed 1330 hours, 3 February 2009. <http://www.eoearth.org/article/Aquifer_depletion;
"The Ogallala Aquifer Depletion," accessed 1337 hours, 3 February 2009. <http://www.iitap.iastate.edu/gcp/issues/society/ogallala/ogallala.html;