acre-foot

An acre-foot volume

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, sewer flow capacity, and river flows.

Definition

It is defined by the volume of one acre of surface area to a depth of one foot. Since the area of one acre is defined as 66 by 660 feet (a chain by a furlong) then the volume of an acre-foot is exactly 43560 cubic feet. Alternatively, this is approximately 325,851.4 U.S. gallons or 271,328.0 imperial gallons or 1,233.5 kL (or m³).

Discussion

As a rule of thumb in U.S. water management, one acre-foot is taken to be the planned water usage of a suburban family household, annually.^[1] In the desert South West, where water conservation is followed and often enforced, a typical family uses only about 0.25 acre-feet of water per year.^[2]

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 m³/s) among seven western U.S. states.

See also

• Cubic metres per second
• Cubic feet per second

References

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