The world's aquifers are being used faster than they can be replenished and, in some cases, at rates that have more than doubled since the 1960s. It is mostly agricultural irrigation that is driving the increase, because it accounts for 70 to 80 percent of global groundwater usage.
An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Some examples of major aquifers follow:
The Great Artesian Basin situated in Australia is arguably the largest groundwater aquifer in the world. It plays a large part in water supplies for Queensland and remote parts of South Australia.
