ABSTRACT
Irrigation can be fundamentally characterized as a temporal adaptation to seasonal and annual variation in rainfall (Turral et al., 2010). As variation in rainfall in both time frames is very common, irrigation is widely practised, and it is considered important from almost all perspectives. Many reasons support the importance of irrigation. Irrigation of lands accounts for over 70 per cent of fresh water consumed in the world, and is also a major user of energy for farming operations and pumping. Irrigated land constitutes approximately 18 per cent of the world’s total cultivated farmland, but produces more than 40 per cent of its food and fibres. Irrigated agricultural activities support diverse components of the world’s food chain and provide much of the fruit, vegetables and cereals consumed by humans plus the grain fed to animals that are used eventually as human food. It also provides much of the feed to sustain animals used for work in many parts of the world, and these lands provide considerable sources of food and foraging areas for migratory and local birds, as well as for other wildlife.
