Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers.
How much do we depend on groundwater?
Groundwater supplies drinking water for 51% of the total U.S. population and 99% of the rural population.
Groundwater helps grow our food. 64% of groundwater is used for irrigation to grow crops.
Groundwater is an important component in many industrial processes.
Groundwater is a source of recharge for lakes, rivers, and wetlands.
Aquifers are typically made up of gravel, sand, sandstone, or fractured rock, like limestone. Water can move through these materials because they have large connected spaces that make them permeable. The speed at which groundwater flows depends on the size of the spaces in the soil or rock and how well the spaces are connected.
Groundwater can be found almost everywhere. The water table may be deep or shallow; and may rise or fall depending on many factors. Heavy rains or melting snow may cause the water table to rise, or heavy pumping of groundwater supplies may cause the water table to fall.
Groundwater supplies are recharged, by rain and snow melt that seeps down into the cracks and crevices beneath the land's surface. In some areas of the world, people face serious water shortages because groundwater is used faster than it is naturally replenished. In other areas groundwater is polluted by human activities.
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