artificial supply of water to crops beyond natural rainfall
methods: flood, furrow, sprinkler, drip, subsurface
drip irrigation delivers water directly to root zone, minimizes waste
historically enabled river civilizations: Nile, Tigris-Euphrates, Indus, Yellow River
modern systems use pump technology and sensors for precision delivery
links water cycle to agriculture: diverts surface and groundwater
overuse causes salinization, aquifer depletion, ecosystem disruption
efficient irrigation is a pillar of food sovereignty
energy cost of pumping is a major constraint in arid regions