Definition: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Input: Some aquifers are overused; people pump out more water than is replaced. As the water is pumped out, the water table slowly falls, requiring wells to be dug deeper, which takes more money and energy. Wells may go completely dry if they are not deep enough to reach into the lowered water table. Other problems may stem from groundwater overuse. Subsidence and saltwater intrusion are two of them. The Ogallala Aquifer supplies about one-third of the irrigation water in the United States. The Ogallala Aquifer is widely used by people for municipal and agricultural needs. (Figure 1.2). The aquifer is found from 30 to 100 meters deep over an area of about 440,000 square kilometers! The water in the aquifer is mostly from the last ice age. About eight times more water is taken from the Ogallala Aquifer each year than is replenished. Much of the water is used for irrigation (Figure 1.3). Click image to the left or use the URL below. URL: Intense drought has reduced groundwater levels in the southern U.S., particularly in Texas and New Mexico. Lowering the water table may cause the ground surface to sink. Subsidence may occur beneath houses and other structures (Figure 1.4). When coastal aquifers are overused, salt water from the ocean may enter the aquifer, contaminating the aquifer and making it less useful for drinking and irrigation. Salt water incursion is a problem in developed coastal regions, such as on Hawaii.
