Between 2000 and 2010, groundwater depletion
caused by irrigation increased 22 percent.
NASA scientists and colleagues used Earth observations and models
to understand where this groundwater depletion is most severe.
The most overexploited aquifers: the North and South Arabian,
Persian, Western Mexico and Upper Ganges,
all show evidence of groundwater depletion from irrigation.
In drier countries like Kuwait, Iran and Saudi Arabia,
crops require extremely large amounts of groundwater-depleting irrigation to grow.
For example, rice grown in Pakistan causes eight times more groundwater depletion per unit
than in India, where surface water resources are more plentiful.
International trade moves these crops between countries,
so in some cases, the countries consuming the most groundwater depletion-linked crops
may have more water supplies, relatively speaking.
However, importers of groundwater depleting-crops
face a potential future food supply risk, as overexploited aquifers
may not be able to continue providing water
at current levels in the long-term.