|Guidelines on spate irrigation (FAO)|
Spate irrigation is an ancient practice by which floodwater is diverted from its river bed and channelled to basins where it is used to irrigate crops and feed drinking-water ponds, serve forest and grazing land and recharge local aquifers. It has evolved over the centuries and provided rural populations in arid and semi-arid regions with an ingenious way to cope with the aridity of their climate. It is thought that spate irrigation started in present-day Yemen, where it has been practised for around five thousand years.
Today, spate irrigation covers more than 3 million hectares across the world. Although its extent is relatively minor compared to other types of irrigation, it represents a unique option for the management of scarce water resources in support of agricultural production and rural livelihoods in many arid regions.
Spate irrigation has been largely neglected in the technical literature. There are no available guidelines that discuss the specificities of spate irrigation. Yet it is different from conventional irrigation in many ways and therefore needs special skills and approaches of which practitioners are not always aware. In particular, standard design approaches cannot appropriately take into account the level of uncertainty related to floods, the hydraulic challenge of guiding flood flows, the heavy sediment loads, the exceptional nature of the water rights, or the management and maintenance models that are specific to spate irrigation.
The main objective of this FAO publication is therefore to assist planners and practitioners in designing and managing spate irrigation projects. It covers hydrology, engineering, agronomy, local organizations and rules, wadi basin management and the economics. It is designed to be both a practical guidance document and a source of information and examples based extensively on experience from around the world in areas where spate irrigation is practised.
2. The social setting
3. Hydrology and sediment transport
4. Water diversion and control structures
5. Soil and field water management
6. Agricultural practices and extension services
7. Water rights and water distribution rules
8. Management arrangements
9. Economics of spate irrigation
10. Spate irrigation in the context of river basin resource management
11. Recommendations for interventions in spate irrigation