Groundwater

Groundwater is water beneath Earth’s surface stored in soil pores, fractures, and permeable rock. It moves through saturated materials and supplies wells, springs, streams, and ecosystems.

Aquifer: A permeable geological formation that stores and transmits usable quantities of groundwater. Aquifers are the formations through which much groundwater is stored and conveyed.
Porosity: The fraction of a material’s volume occupied by void spaces. Pore space provides storage for groundwater in sediments and rock.
Water well: A drilled or dug opening that accesses groundwater for monitoring or withdrawal. Wells make groundwater available for drinking, irrigation, and industry.
Baseflow: The portion of streamflow sustained between storms, often by groundwater discharge. Groundwater discharge keeps many streams flowing when rain and runoff are scarce.
Groundwater recharge: The process by which water enters a saturated underground formation. Recharge replenishes groundwater as precipitation or surface water infiltrates downward.
Permeability: The capacity of a material to transmit fluids through connected pores or fractures. Connected pathways determine whether stored groundwater can move.
Groundwater pumping: The extraction of water from underground formations, usually through wells. Pumping supplies people but can lower water levels and alter natural flows.
Groundwater depletion: A sustained decline in groundwater storage when withdrawals exceed replenishment. Persistent overuse reduces reserves and can impair wells, streams, and ecosystems.
Hydraulic conductivity: A measure of how readily a porous material transmits water under a hydraulic gradient. It helps determine how quickly groundwater can flow through different materials.
Saturated zone: The subsurface region where all connected pore spaces are filled with water. Groundwater occupies this zone beneath the water table.

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