Spate irrigation occurs in areas as varied as South Asia, the Middle East, West Africa, North Africa, the Horn of Africa, Central Asia and Latin America. Estimates for the area under flood irrigation are not easy to make, as the area under spate irrigation changes from year to year and as spate irrigation has never had the amount of attention from development agencies or tax authorities, that perennial irrigation has had. Spate irrigation is typically found in arid and semi-arid regins, where highlands border plains. It uses seasonal floods for irrigation – but as the floods differ from year to year the area served by it fluctuates widely.
The most comprehensive information on how much spate irrigation there is comes from FAO.
|Country||Year||Area under Spate Irrigation in Hectares|
|Iran||2008||450,000 – 800,000|
|Pakistan||1999||640,000 – 1,280,000|
|Yemen, Rep. of||1999||117,000|
Sources: FAO Aquastat and “Spate Irrigation, Livelihood Improvement and Adaptation to Climate Change Variability.“
The figures for these selected countries indicates an order of magnitude. Some figures are debatable. The area under spate irrigation in Eritrea is also quoted as 90,000 ha. For Pakistan – where spate irrigation is found in all four provinces – an estimate of 3.250,000 has been mentioned by other sources. Further spate irrigation is reported from North Chile and Bolivia, Iran, Afghanistan, Mauretania and Senegal, Ethiopia, Kenya and the Northwest coast of Egypt.