for agriculture it includes irrigation to smooth water supply across the production seasons water management in rainfed agriculture management of floods droughts and drainage conservation of ecosystems and meeting cultural and recreational needs linked to water oecd a for most countries agriculture is largely rainfed but in areas susceptible to variable precipitation irrigation is used to supplement rainfall mainly drawing on freshwater from surface and groundwater sources ie shallow wells and deep aquifers and to a lesser extent recycled wastewater and desalinated water water resource management in agriculture also operates in a highly diverse set of political cultural legal and institutional contexts encompassing a range of areas of public policy agriculture water environment energy fiscal economic social and regional