The Green Revolution made is possible for agriculture to increase yields exponentially, saving millions of people from starvation. Part of the Green Revolution of the 60s and 70s was the introduction of widespread irrigation that allowed crops to be grown in areas previously thought too dry.
In the American west, a huge underground aquifer known as the Ogallala Aquifer or the High Plains Aquifer, has provided water to eight states and supported extensive farming activities. Land once considered too dry to farm has become a major producer of grains to the world. The US crops in 2014 were valued at around USD 125 billion.
While the money associated with the sale of agricultural products is an important addition to the US economy, many people in developing countries depend on the generosity of that government in the form of food aid. That aid may be tapering off over the next few years as drought and the drawing down of water sources becomes more acute.
The Ogallala Aquifer is becoming depleted. It is estimated that the reservoir may have filled 15 000 years ago. Some of it is replenished in the rainy season, but states like Kansas, Oklahoma and Texas lack enough rainfall to balance the water withdrawal. The US Department of Agriculture is taking steps to educate and support those in the dry land states to slow the depletion of the resource.
The depletion of ground water is not confined to the USA. Aquifers in S. America and N. Europe and Russia are in good shape. Those in Mexico, North Arabian Peninsula, Iran, Upper Ganges Valley and the N. China Plain are being drawn down faster than they are being replenished.
A find of fossil water in Libya has allowed for extensive agriculture in what was once desert. Using fossil water is much like mining for a valuable ore. It will not be replenished.
With the combination of a rapidly increasing population that is expected to reach 9 billion by 2040, the demands on water supplies will continue to increase whether it is for agriculture, energy production, drinking.
[Fossil water or paleowater is groundwater that has remained sealed in an aquifer for a long period of time. Water can rest underground in “fossil aquifers” for thousands or even millions of years.18 Oct 2010]
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