People everywhere have a disturbing tendency to view groundwater as an inexhaustible resource and to extract it far more quickly than it can recharge. Furthermore, many do not realize that much of the water they see in a river (especially during the dry season) is actually “baseflow” from groundwater that is connected to the river, rather than surface runoff from tributary streams— and that pumping groundwater even from wells many miles away can still cause the river to shrink or dry up.
Groundwater provides about one- fifth of humanity’s freshwater. It consists of rainfall that percolates from the surface down into aquifers, where it is stored, free from evaporation. Depending on the silt, sand, and rock it has to pass through on its underground journey, groundwater can be days, years, or even millions of years old. Libya’s Great Manmade River taps fossil water that accumulated beneath the Sahara forty thousand years ago— and is unlikely to be replenished anytime soon. This is known as “water mining,” extracting water in the clear knowledge that it will eventually run out completely.
In the United States, for instance, groundwater supplies more than half of all drinking water and more than one- third of all agricultural water needs. The huge Ogallala aquifer, which underlies eight states in the American Midwest and is extensively used to grow food, is being depleted at ten times the rate of natural recharge, and some experts fear it could dry up completely within twenty- five years. In places, the depletion rate was more than one hundred feet until 1980 and was more than forty feet between 1980 and 1997. This highlights a critical issue: once aquifers are pumped dry, they can collapse and then cannot be recharged ever again.24 In India, groundwater tables have been dropping as much as three feet a year in many regions, forcing poor farmers who cannot afford gasoline- powered pumps to abandon irrigated food production. According to Neerjaal, a maker of software for monitoring and conserving groundwater, “Indian surveyors have divided the country into 5,723 geographic blocks. More than 1,000 are considered either overexploited, meaning more water is drawn on average than is replenished by rain, or critical, meaning they are dangerously close to it.” A recent report found that groundwater exploitation was particularly severe in the vital food bowl states of Punjab, Haryana, Gujarat, Maharashtra, and Andhra Pradesh.
Water Management Policies
