acrefeet

An acre-foot is a unit of volume used in the United States and Canada for water-resource management. It represents the volume of water required to cover one acre of land to a depth of one foot. This equals 43,560 cubic feet (approximately 1,233 cubic meters) and is about 1.233 megaliters.

The acre-foot is commonly used to describe reservoir capacities, annual water allocations, irrigation demands, and other planning benchmarks. It provides a practical way to compare amounts of water across different projects and regions because it ties volume to land area and depth.

Because it is not part of the International System of Units, conversions are routinely provided when communicating with international audiences. In hydrology, the term may appear as acre-feet per year or acre-feet per season to express flow or availability over time.

In practice, large reservoirs and irrigation districts measure storage and withdrawals in acre-feet, while researchers may convert values to megaliters or cubic meters for reporting. The unit remains a common reference in U.S. water planning and policy discussions, reflecting historical land-measurement customs and the local context of water supply management.