As a testimony of the diversity in development in the world, spate irrigation on the decline in rich areas such as Saudi Arabia, but is on the increase in low income countries such as Ethiopia and Eritrea. Generally spate irrigation is associated with low returns per labour, great variability in income between good and bad years and a high degree of social organisation to maintain the systems. Where more rewarding sources of income come up, where a period of long droughts force people to abandon their area or where the local organisation is undermined spate irrigation systems may disappear.
Another important change in several areas, that are traditionally spate irrigated is the introduction of groundwater irrigation. In many spate irrigated areas groundwater resources are relatively rich due to long periods of recharge. With the availability of relatively inexpensive pumpsets groundwater has become an important source of irrigation, for instance in spate areas in Dera Ghazi Khan (Pakistan), Tunesia or Yemen. This has resulted in a neglect of the spate infrastructure and a change towards perennial cropping.
The number of public programs to support spate irrigation have been relatively limited. One reason has been the difficulty to justify investments in civil engineering works on systems, dominated with low value farming. The second reason has been that it has been hard to identify successful interventions in spate systems, because spate systems are often hydraulically and socially generally very complex.
An alternate approach to support spate systems has been the subsidization of mechanical traction. This approach has been followed with a relative high degree of success in Pakistan and Tunesia. Bulldozer programs have put a very useful resource at the hand of local spate farmers – who have remained in charge of the design and implementation. The cost effectiveness of bulldozer has been relatively high, moreover.