Living in the Environment chapter 13

Aquifer

Porous, water-saturated layers of sand, gravel, or bedrock that can yield an economically significant amount of water.

Dam

A structure built across a river to control the river's flow or to create a reservoir.

Desalination

Purification of salt water or brackish (slightly salty) water by removal of dissolved salts.

Drainage basin/Watershed

Land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river).

Drought

Condition in which an area does not get enough water because of lower-than-normal precipitation or higher-than-normal temperatures that increase evaporation.

Floodplain

Flat valley floor next to a stream channel. For legal purposes, the term often applies to any low area that has the potential for flooding, including certain coastal areas.

Ground water

Water that sinks into the soil and is stored in slowly flowing and slowly renewed underground reservoirs called aquifers; underground water in the zone of saturation, below the water table.

Natural recharge

Natural replenishment of an aquifer by precipitation, which percolates downward through soil and rock.

Recharge area

Any area of land allowing water to percolate down through it and into an aquifer.

Reliable runoff

Surface runoff of water that generally can be counted on as a stable source of water from year to year.

Resevoir

Artificial lake created when a stream is dammed.

Subsidence

Slow or rapid sinking of part of the earth's crust that is not slope-related.

Surface runoff

Water flowing off the land into bodies of surface water.

Surface water

Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation or transpiration.

Virtual water

Water that is not directly consumed but is used to produce food and other products.

Water footprint

A rough measure of the volume of water that we use directly and indirectly to keep a person or group alive and to support their lifestyles.

Water table

Upper surface of the zone of saturation, in which all available pores in the soil and rock in the earth's crust are filled with water.

Zone of aeration

Zone in soil that is not saturated with water and that lies above the water table.

Zone of saturation

Zone where all available pores in soil and rock in the earth's crust are filled by water.