Acre-foot


The acre-foot is a non-SI unit of volume equal to about commonly used in the western United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water, and river flows.
An acre-foot equals the volume of water needed to fill approximately an eight-lane swimming pool, long, wide and deep.

Definitions

As the name suggests, an acre-foot is defined as the volume of water that would cover one acre of surface area to a depth of one foot.
Since an acre is defined as a chain by a furlong, an acre-foot is.
There have been two definitions of the acre-foot, using either the international foot or a U.S. survey foot. On December 31, 2022, the National Institute of Standards and Technology, the National Geodetic Survey, and the United States Department of Commerce deprecated use of the US survey foot and recommended conversion to either the meter or the international foot.

Application

As a rule of thumb in US water management, one acre-foot is taken to be the planned annual water usage of a suburban family household. In some areas of the desert Southwest, where water conservation is followed and often enforced, a typical family uses only about of water per year. One acre-foot per year is approximately.
The acre-foot per year has been used historically in the US in many water-management agreements, for example the Colorado River Compact, which divides among seven western US states.
Water reservoir capacities in the US are commonly given in thousands of acre-feet, abbreviated TAF or KAF.
In most other countries except the US, the metric system is in common use and water volumes are normally expressed in liter, cubic meter or cubic kilometer. One acre-foot is approximately equivalent to. Large bodies of water may be measured in cubic kilometers ;.
A volumetric change of 10 acre-feet per hour is equivalent to exactly 121 cubic feet per second. Dividing by 120, this reduces to 1 acre-inch per hour is approximately. This can be visualized as such: suppose a 1-acre field is receiving a sustained rainfall of 1 inch per hour. In order prevent the field from flooding or overflowing, the drainage system must be able to handle a discharge of at least 1 cubic foot per second.