Acre foot
From Wikinfo
An acre foot is a unit of volume commonly used in the United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, and river flows.
Definition
It is defined by the volume of water necessary to cover one acre of surface area to a depth of one foot. It is equal to exactly 43,560 cubic feet, or to nearly 325,851 U.S. gallons, or exactly 1233.48183754752 cubic meters.
Discussion
As a rule of thumb in U.S. water management, one acre foot is taken to be roughly the amount of water used annually by a family of four. The acre foot (or more specifically the time rate unit of acre foot per year) has been used historically in the U.S. in many water-management agreements, for example the Colorado River Compact, which divides 15 million acre feet per year (586 m�/s) among seven western U.S. states.
References
- Adapted from the Wikipedia article, "Acre_foot" http://en.wikipedia.org/wiki/Acre_foot, used under the GNU Free Documentation License
