The practice of supplying land with water from another place using canals is called irrigation.
Irrigation is the deliberate application of water to soil so crops or other plants can grow when rainfall is insufficient, unreliable, or poorly timed. Canals are one of its oldest and most important tools, carrying water from rivers, reservoirs, or lakes to fields through a network of channels.
Early irrigation systems helped support major civilizations in river valleys such as Mesopotamia and ancient Egypt. Modern systems may use open canals, pipes, sprinklers, or drip lines. The basic purpose remains the same: move water from a source to cultivated land and distribute it where plant roots can use it.
Irrigation is not the same as drainage. Irrigation adds water to land, while drainage removes excess water. Poorly managed irrigation can cause waterlogging, soil salinity, and waste through evaporation or leakage. Large canal projects can also reshape regional economies, as seen with the Karakum Canal, which carries Amu-Darya water across Turkmenistan's Karakum Desert.