- 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