As a general rule, the most successful man in life is the man who has the best information.
Freshwater aquifers are one of the most important natural resources in the world today but were pumping the groundwater out of them so fast nature can't recharge them. Many places we're pumping water out of it's just like your mining it - once the water is pumped out its gone forever, it isn't coming back anymore than the gold in a mined out gold deposit could.
These fast shrinking underground reservoirs are essential to life on this planet. They sustain streams, wetlands, and ecosystems and they resist land subsidence and salt water intrusion into our fresh water supplies.
Many people think of aquifers as underground lakes but that's not the case - the water is held between rock particles. Water infiltrates into the soil through pores and cracks until it reaches what is called the zone of saturation - all of the spaces between the rocks are filled with water, not air. This zone of saturation occurs because water infiltrating the soil reaches an impermeable layer of rocks it can't soak through.
There are two types of aquifers: replenishable (a permeable layer of rock above the water table and an impermeable one beneath it) and non-replenishable (also known as fossil aquifers, no recharge) 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 or refill.
For fossil aquifers - such as the vast U.S. Ogallala aquifer, the deep aquifer under the North China Plain, or the Saudi aquifer - depletion brings pumping to an end.
The Ogallala Aquifer (a south to north trend consisting of thick sands and gravels) is the leading geologic formation in what is known as the High Plains Aquifer System. The Ogallala has a total water storage capacity about equal to that of Lake Huron. The entire system underlies about 450,000 square kilometers (174,000 square miles) of eight states - Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming.
On the High Plains there is very little water surplus - evaporation levels are almost the same as precipitation levels meaning there is little recharge of groundwater from precipitation. What little recharge there is for the Ogallala comes from ground water percolating very slowly eastward from Rocky Mountain snowmelt.
The Ogallala waters more than one-quarter of all irrigated acreage in the U.S., provides water for some of world's largest cattle feedlots and four of five people living above it count on the aquifer for their drinking water.
In April 2012, 37 percent of the contiguous U.S. was experiencing at least moderate drought conditions, a number that shot up over 63 percent by mid-summer. Currently 47 percent of the U.S. is experiencing moderate drought conditions.
The main problem with groundwater in the High Plains is that the water is being withdrawn at a rate greater than the recharge rate. The Ogallala Aquifer's recharge rate is approximately 22 to 25 mm/year with a net overdraft of 54.864 mm/year - when pumping from an aquifer extracts water faster than it can be recharged the aquifer is said to be in overdraft.
If the Ogallala Aquifer does dry up (since large-scale irrigation began in the 1940s, water levels have declined more than 30 meters in parts of Kansas, New Mexico, Oklahoma, and Texas) America would need the equivalent of 20 percent of the flow of the St. Lawrence seaway each and every year just to replace the water needed to irrigate the mid-western corn crop - U.S. corn and cotton farmers are growing high water demand crops in a desert.
Aquifer depletion would significantly impact crop production in the United States because 60 percent of irrigation relies on groundwater and 94 percent of the total groundwater usage from the Ogallala is for irrigation.
"Ogallala water allowed the agricultural transformation of the High Plains in the 1950s. Renewed drought led to major well drilling, especially on the Texas High Plains. With the technology now well established, the water pumped and the acreage irrigated increased dramatically. Center-pivot methods of irrigation were patented in 1952, and spread over much of the High Plains in the 1970s. By the mid-1970s, 12 million acres were irrigated, largely for feed corn, with cotton as a major crop in West Texas. Production of feed grains on the High Plains tripled between 1954 and 1973, and the grains were fed to beef cattle in feedlots all over the Plains.
In 1980 about 170,000 wells were pumping 18 maf/yr (more than the flow of the Colorado River) from the Ogallala Formation to irrigate over 13 million acres, compared with 2 million acres in 1949. The Sand Hills of Nebraska, long a wildlife refuge because crops could not be grown on it, now contained some of the most intensive central-pivot irrigation systems in the United States. 20% of the irrigated land in the United States overlay the Ogallala, 30% of the irrigation ground water in the United States was being pumped from it, and 40% of the grain-fed beef cattle slaughtered in the United States were being fattened in the six states of the High Plains. Large feedlots were set up, and slaughtering and meat-packing centers were built to create a significant economic infrastructure. Kansas is the leading state in the US for wheat production and beef-processing.
The mathematics is inexorable. An aquifer does not contain 100% water, because the water is held between the grains in the sediment. Surface tension dictates that not all the water can be pumped out: an aquifer yields only a specific yield, which for the Ogallala is 10-20% of its volume in water.
Over the entire Ogallala region, 23 maf/yr were being pumped in 1978, but that had dropped to 18 maf/yr in 1980 (still more water than flows down the Colorado River!). Finally, with the water table dropping precipitously, the end was in sight. The water table dropped more than 50 feet over a large area in the southern High Plains, and dropped more than 200 feet in West Texas. Nebraska, Kansas, and Texas were pumping 88% of all the Ogallala water between them. It became clear that this underground water was not a renewable resource, and that once pumped out, that would be the end of irrigated farming." mygeologypage.ucdavis.edu
"They have substituted rain-fed agriculture along the Atlantic coast -- because good farmland is being covered up by urban sprawl -- for an unsustainable irrigation-based agriculture in the Midwest. When the aquifer runs dry, which it absolutely will, what will they do?" Peter Brown, director of the McGill School of Environment
Think of pumping most underground water to the surface as mining water. When it's gone - like when a gold, copper or rare earth mine runs out of ore - it's gone.
This fact should be on all our radar screens. Is it on yours?
If not, maybe it should be.