Understanding Groundwater Glossary

aquifer - a geologic formation that is capable of yielding usable amounts of water to a well or spring. 

cone of depression - a drawdown of groundwater in the shape of an inverted cone created by a pumping well.

bedrock - solid rock that forms the earth’s crust (sometimes called ledge; it is intermittently exposed at the earth’s surface but is more commonly covered by soil.

contaminate - to make impure (pollute) by the addition of some substance.

contamination plume - a concentrated mass of pollutant that moves with the groundwater.

drainage basin - the land area that gathers and carries surface runoff and groundwater to a particular stream, river or  lake.

evapotranspiration - loss of water to the atmosphere by direct evaporation from land and water surfaces combined with water transpired by living plants.

groundwater - water, lying below the water table, in the saturated zone.

hydrologic cycle - the distribution and circulation of water above, on, and below the earth’s surface.

infiltration - movement of water into the earth.

pollutant - any solid, liquid, gaseous or radiological element or compound that would render any substance unfit for use.

precipitation - the discharge of water from the atmosphere, in either liquid or solid form.

recharge - replenishment of groundwater by infiltration.

saturated zone - a subsurface zone in which all open spaces in soil or bedrock formation are filled with water; the area lying below the water table surface.

stratified drift - sand, gravel, silt and clay particles that were transported, sorted and deposited in layers of similar grain size by glacial melt waters.

surface water - water that lies on and flows across the land surface as lakes, rivers, streams, and oceans.

till - a largely unsorted mix of boulders, gravel, sand, silt and clay laid on the land directly by glacial ice.

unsaturated zone - a zone extending from the water table up to the land surface and where the openings  between soil particles are only partially filled with water.

water table - the top of the saturated zone; the surface beneath which all open spaces between soil particles are completely filled with water.

watershed - another term for drainage basin.

Understanding Groundwater