Science of Water : Concepts and Applications

416 The Science of Water: Concepts and Applications
W
Wastewater The spent or used water from individual homes, a community, a farm, or an industry
that contains dissolved or suspended matter.
Water budget An accounting of the infl ow to, outfl ow from, and storage changes of water in a
hydrologic unit.
Water column An imaginary column extending through a water body from its fl oor to its
surface.
Water demand Water requirements for a particular purpose, such as irrigation, power, municipal
supply, plant transpiration, or storage.
Water table The top water surface of an unconfi ned aquifer at atmospheric pressure.
Waterborne disease Water is a potential vehicle of disease transmission, and waterborne disease
is possibly one of the most preventable types of communicable illness. The application
of basic sanitary principles and technology have virtually eliminated serious outbreaks
of waterborne diseases in developed countries. The most prevalent waterborne diseases
include typhoid fever, dysentery, cholera, infectious hepatitis, and gastroenteritis.
Water softening A chemical treatment method that uses either chemicals to precipitate or a zeolite
to remove those metal ions (typically Ca 2+ , Mg 2+ , Fe 3+ ) responsible for hard water.
Watershed The land area that drains into a river, river system, or other body of water.
Wellhead protection The protection of the surface and subsurface areas surrounding a water well
or well fi eld supplying a public water system from contamination by human activity.
Y
Yield The mass of material or constituent transported by a river in a specifi ed period of time
divided by the drainage area of the river basin.