Ground-penetrating radar

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.

Overview

Groundwater is one of the most important sources of water on earth. It is the water that fills the pores and fractures in the ground beneath our feet. It originates from rain and from melting snow and ice and is the source of water for aqueducts, springs and wells. The upper surface of the groundwater is the water table.

Aquifers

An aquifer is a body of rock and/or sediment that holds groundwater. There are two types of aquifers: unconfined and confined. Unconfined aquifers are those into which water seeps from the ground surface directly above the aquifer. Confined aquifers are those in which an impermeable dirt/rock layer exists that prevents water from seeping into the aquifer from the ground surface located directly above. Instead, water seeps into confined aquifers from farther away where the impermeable layer doesn't exist.

Groundwater Movement

Groundwater moves from areas of high pressure to areas of low pressure and it tends to move slowly. The speed at which groundwater flows is determined by the permeability and porosity of the rock and soil materials it is moving through.

Groundwater and the Water Cycle

Groundwater plays a vital role in the water cycle. It is the source of water for evaporation and transpiration. It also contributes to rivers and lakes.

Groundwater Quality

The quality of groundwater is influenced by the quality of the recharged water, atmospheric inputs, the type and quantity of the surrounding soils and rocks, and the age of the groundwater. Groundwater can be contaminated by human activities or can naturally contain disease organisms or high levels of minerals and gases.

Groundwater Depletion

Groundwater depletion, a term often defined as long-term water-level declines caused by sustained groundwater pumping, is a key issue associated with groundwater use. Many areas of the United States are experiencing groundwater depletion.

See Also

• Water cycle
• Aquifer
• Water table
• Water pollution