A data set of annual values of area equipped for irrigation for all 236 countries in the
world during the time period 1900 - 2003 was generated. The basis for this data product
was information available through various online data bases and from other published
materials. The complete time series were then constructed around the reported data
applying six statistical methods. The methods are discussed in terms of reliability and
data uncertainties. The total area equipped for irrigation in the world in 1900 was 53.2
million hectares. Irrigation was mainly practiced in all the arid regions of the globe and in
paddy rice areas of South and East Asia. In some temperate countries in Western Europe
irrigation was practiced widely on pastures and meadows. The time series suggest a
modest rate of increase of irrigated areas in the first half of the 20th century followed by a
more dynamic development in the second half. The turn of the century is characterized by
an overall consolidating trend resulting at a total of 285.8 million hectares in 2003. The
major contributing countries have changed little throughout the century. This data
product is regarded as a preliminary result toward an ongoing effort to develop a detailed
data set and map of areas equipped for irrigation in the world over the 20th century using
sub-national statistics and historical irrigation maps