Irrigation is the watering of land by artificial methods. It provides water for plant growth in areas that have long periods of little or no rainfall. The water used for irrigation is taken from lakes, rivers, streams, and wells. Irrigation is used chiefly in three types of climates. In desert regions, such as Egypt and the Southwestern United States, farming would be impossible without irrigation. In regions with seasonal rainfall, such as California and Italy, irrigation makes farming possible even during dry months.
Fact file
In the mid-1980's, about 550 million acres (220 million hectares) of land were under irrigation throughout the world. Rice is one of the world's most important food crops. Lowland rice is grown in flat fields that are flooded by irrigation.
