Groundwater

Definitions Available stores of natural water are made up of groundwater, impounded of flowing surface water and seawater. Groundwater is water that exists in the pore spaces and fractures in rock and sediment beneath the Earth's surface. It originates as rainfall or snow, and then moves through the soil into the Groundwater system, where it eventually makes its way back to surface streams, lakes, or oceans. It is naturally replenished from above, as surface water from precipitation, streams, and rivers infiltrates into the ground. Groundwater is a long-term reservoir of the natural water cycle, as opposed to short-term water reservoirs like the atmosphere and fresh surface water. The Groundwater table is the surface of the Groundwater exposed to an atmospheric pressure beneath the surface of the saturated zone. A water table may vary in elevation.

Groundwater is often contained in aquifers: an aquifer is an underground water saturated stratum of formation that can yield usable amounts of water to a well. There are two different types of aquifers based on physical characteristics: if the saturated zone is sandwiched between layers of impermeable material and the Groundwater is unfed pressure, it is called a confined aquifer; if there is no impermeable layer immediately above the saturated zone, it is called an unconfined aquifer. In an unconfined aquifer the top of the saturated zone is the water table as defined above. Usually an aquifer can produce an economically feasible quantity of water to a well or spring. A saturated region that, due to lower hydraulic conductivity, does not yield a sustainable amount of water in an economic fashion is called aquitard.

For more information about groundwater check the following pages: groundwater properties, origin and quantity, sources in Europe, contamination.

For terminology on water please check our Water Glossary

For more books and reading information see our website:
Groundwater books overview