Irrigated systems have expanded in recent years to bring water control, which, together with rapid increases in water productivity, has greatly boosted agricultural production and incomes. Groundwater abstraction has provided an invaluable source of ready irrigation water but has proved almost impossible to regulate. As a result, agricultural withdrawals of groundwater are intensifying, and some key aquifers around the world are being depleted.
Water quality is deteriorating, with impacts from irrigation on both surface and groundwater, and the salinization of irrigated lands is a growing problem. Groundwater salinization by irrigation return-flows is a serious long-term concern for the sustainability of both water resources and irrigated agriculture.