Groundwater and Water Supply

Changes in snowmelt may also affect groundwater. Groundwa-ter is water located underneath the ground, either in porous soil or in spaces in rock. An underground area that can yield usable water is called an aquifer. Groundwater from aquifers is an important source of water for both agriculture and industry.

Researchers believe that snowfall from winter storms is the major source for replenishing groundwater in the southwestern United States. This is because groundwater recharge tends to happen during floods such as those that occur with winter melt. Thus, "As the snowline retreats to cover smaller and smaller areas, and as the snowpack itself declines because of more rain and less snow and more intermittent melting . . . it seems really likely that recharge will decline in many parts of the Southwest," according to U.S. Geological Survey researcher Michael Dettinger.16

Groundwater is an especially important source for human and agricultural use in Africa. With climate change altering rainfall, the flow of rivers, and the level of lakes, groundwater is expected to be both more heavily relied upon and a less reliable source of drinking water on the African continent. Despite its importance in Africa and elsewhere, however, "The impact of climate variability and change on groundwater resources remains . . . one of the most persistent knowledge gaps identified by the Intergovernmental Panel on Climate Change____" according to geographer Richard Taylor.17

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