Chapter 11

aquifer

\
caverns and porous layers of sand, gravel, or rock through which groundwater flows  

cultural eutrophication

\
process of accelerated eutrophication, as animal feedlots, urban streets and parking lots   

dam

a structure built across a river to control its flow   

dead zone

the resulting massive volume of water with a low dissolved oxygen content is called a dead zone 

desalination

the process of removing dissolved salt from ocean water or from brackish water in aquifers or lakes  

drainage basin

land area that delivers water, sediment, and dissolved substances via small streams to a major stream   

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 

eutrophication

a natural nutrient enrichment of a shallow lake, coastal area at the mouth of a river   

floodplain

when freshwater in a stream or river overflows its normal channel and spills into the adjacent area 

freshwater

water that contains very low levels of dissolved salts   

groundwater

freshwater in spaces such as soil, gravel, rock until an impenetrable layer of rock or clay stops it  

irrigation

supplying water to crops by artificial means rather than by relying on natural rainfall 

non point sources

\
are broad and diffuse areas where rainfall or snowmelt washes pollutants off the land into bodies of surface water 

point sources

discharge pollutants into bodies of surface water at specific locations through drain pipes, ditches, or sewer lines.

primary sewage treatment

a physical process that uses screens and a grit tank to remove large floating objects and to allow solids such as sand and rock to settle out 

reliable surface runoff

regarded as a stable source of freshwater from year to year makes up 1/3, the other 2/3 is not available for human use  

secondary sewage treatment

\
a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen-demanding organic wastes 

septic tank

underground tank for treating wastewater from a home, used in rural and suburban areas. Bacteria in the tank decomse organic wastes, and the sludge settles to the bottom of the tank. The effluent flows out of the tank intothe ground through a field of drainpipes  

subsidence

slow or rapid sinking of part of the earths crust that is not slope related 

surface runoff

\
precipitation that does not soak into the ground or return to the atmosphere by evaporation 

surface water

the fresh water from rain and melted snow that is stored in lakes, reservoirs, wetlands, streams, and rivers. 

wastewater

any water that contains sewage, other wastes, or polluting chemicals from homes and industries

water footprint

a rough measure of the total volume of freshwater you use directly or indirectly   

water pollution

\
 any change in water quality that can harm living organisms or make the water unfit for human uses such as drinking, irrigation, and recreation. Can come from a single source for form larger and dispersed (nonpoint) sources 

water table

top of the groundwater zone   

watershed

the land from which surface runoff drains into a particular stream, lake, wetland, or other body of water 

zone of saturation

the spaces in soil and rock close to the earth’s surface hold little moisture, below a certain depth they are filled with freshwater