Chapter 15

• Water Cycle • Biogeochemical cycle that collects, purifies, and distributes the earth’s fixed supply of water from the environment to living organisms and then back to the environment

• The precipitation that does not infiltrate the ground or return to the atmosphere by evaporation • including transportation from plants

-The region from which surface water drains into a river, lake, wetland, or other body of water

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

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

-Area where all available pores in soil and rock in the earth’s crust are filled by water

-Uper 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

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

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

-Drying of exposed soil because of activities such as deforestation and overgrazing by livestock

-Low per capita availability of water caused by increasing numbers of people relying on limited runoff

-Movement of salt water into freshwater aquifers in coastal and inland areas as groundwater is withdrawn faster than it is recharged by precipitation

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

-Heating salt water until it evaporates, leaving behind salts in solid form, and it condenses as fresh water

-Pumping salt water at high pressure through a thin membrane with pores that allow water molecules, but not most dissolved salts, to pass through

• A form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds • Dispersing substances into the air that serve as cloud condensation or ice nuclei -I couldn’t find in textbook

• Replacing green lawns with vegetation adapted to a dry climate because of water-short areas • Win-Win approach • Reduces water use by 30-85% and sharply reduces the need for labor, fertilizer, and fuel • Reduces polluted runoff, air pollution, and yard wastes

• 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