Spate irrigation is a type of water management unique to arid regions bordering highlands. It is common in South Asia, the Middle East, North Africa and the Horn of Africa.
Sudden floods, or spates, originate from sporadic rainfall in macrocatchments. After the land is inundated, crops are sown – sometimes immediately, but often the moisture is stored in the soil profile and used later. Spate irrigation systems support farming systems – usually cereals and oilseed, but also cotton, pulses and even vegetables.
There are no accurate data on the area under spate irrigation globally, but estimates place it at 2.0-2.5 million hectares (ha). The largest area under spate irrigation is in Pakistan (1,402,000 ha). There are also substantial areas in Somalia (150,000 ha), the Sudan (146,000 ha), Yemen (115,000 ha), Algeria (110,000 ha), Ethiopia (100,000 ha) and Morocco (79,000 ha). In several countries the area under spate irrigation is more or less stable, but in the Horn of Africa it is expanding rapidly. In all cases, there is a large untapped potential to improve food production and livelihoods in spate-irrigated areas.
Spate irrigation systems are among the most fascinating and complex resource management systems.
Uncertainty is a defining characteristic. The number and sequence of floods vary from one year to another. So do yields, which can be high however.
A second important characteristic is that sedimentation is as important as water management. Rivers in spate lift and deposit huge quantities of sediment. As a result there is constant change in bed levels, in both the river system and the distribution network. The uncertainty, occurrence of high flood peaks and heavy sedimentation mean that conventional irrigation modernization approaches are inappropriate.
There are, however, a number of ways to improve spate irrigation systems:
- Improve local diversion structures, ensuring that improvements do not interfere with established water distribution rules or expose the command area to risk of damaging high floods or heavy sedimentation. A wide range of options exists for civil engineering improvements, the use of gabion works, stone abutments and/or soil bunds using earth-moving equipment.
- Improve water productivity and soil moisture management. There are several ways to achieve this. First is the use of improved field-to-field structures (inlets and overflow structures), allowing more regulated inflows and outflows during the hectic spate period. Another strategy is to ensure that animal traction power is adequate for ploughing and mulching, so as to conserve soil moisture after irrigation. A final strategy is to consider concentrating flows into a relatively compact command area. More-compact command areas also increase the chance of a second and third irrigation, taking crops out of the ‘stress zone’.
- Improve field preparations, seed treatment, use of improved seed, early planting and targeted use of agrochemicals.
- Introduce new crops – vegetables, cucurbits, pulses, oilseed. Introduce post-harvest technologies such as seed cleaning and improved storage.
- Promote local agroforestry, particularly indigenous trees. This serves to stabilize surrounding areas and provides fuel, timber, medicines and bee forage.
- Improve drinking water facilities in spate areas. These are often unprotected open ponds, but they can be improved by a range of technical and institutional improvements.
- Improve land and water tenure, issuing individual titles where they do not exist and codifying or reviewing water rights so as to minimize conflicts and accommodate new realities – such as intense use of groundwater and the need for recharging.
- Work on the bigger picture – improve access roads to spate-irrigated areas, general amenities and market facilities.
Spate-irrigated areas are remote and forgotten. They face considerable challenges:
Absolute lack of support systems
Spate irrigation systems are generally situated in remote areas where there is deep-seated poverty and support systems are weak.
There is often little equipment and few market facilities that could upgrade production systems. In several spate-irrigated areas in Ethiopia, there is no access to the earth-moving equipment that would make a big difference in developing diversion structures and rehabilitating land and channel systems.
Some systems on the edge
Some spate irrigation is marginal in the sense that its sustainability is vulnerable. In Kharan, in Pakistan, a series of dry years undermined the local livelihood base and many families were forced to migrate. With them went the critical mass needed to construct diversion structures and maintain field structures.
Little support to agronomy
There has been little effort to systematically support agronomy in spate irrigation – with little research in general, and weak research on field linkages or international sharing of experience.
Importance of inequity
There is much variation among areas and countries, but some spate irrigation systems in the Tihama area of Yemen and the Kacchi plains in Pakistan are characterized by substantial inequality or generally complex tenure relationships that complicate local cooperation and fair water distribution.
Spate irrigation has been invisible in policy. Knowledge of spate irrigation systems is extremely limited. The most telling example is Pakistan. Although an estimated 9 per cent of the agricultural land or 1,402,000 ha is under spate irrigation, there is no university course, no recent publication and no significant support programme for this form of irrigation – despite the fact that spate-irrigated areas account for most of the national production of oilseed and pulses.
Spate irrigation has suffered from inappropriate approaches in the past. In the 1980s and 1990s, ‘modernization’ was popular, with heavy investment in sophisticated headworks. In many cases, these interventions were inappropriate: they suffered from heavy sedimentation, were not able to handle flood flows, disturbed local water distribution rules, or simply failed. A review of such approaches in Balochistan (Pakistan) indicated that 65 per cent of the modernized systems were no longer functioning.
Intersectoral management is a relatively new, holistic approach that offers a promising framework for better understanding and pro-poor mobilization of potential development synergies. In IFAD’s approach to water, this theme is not central, but is considered a holistic element in strengthening poor rural people's livelihoods and resilience. IFAD investment approaches to water-related interface management take into account the country-specific structures of the rural political economy. In so doing, they support the development of pro-poor, community-based natural resource management (NRM) institutions, which in turn improve farmer-led agriculture, natural resource technologies, and the sharing of knowledge of these achievements.
With regard to spate irrigation, IFAD is a leading international player, having supported system improvements in projects in Eritrea, the Sudan, Tunisia and Yemen. The projects followed an integrated approach that went beyond water resource development, and the methods advocated by IFAD were largely based on its experience in the field.
- Strengthen local organization for water management functions at wadi and sub-basin levels, study water distribution, recharge and sedimentation processes for the entire river section, and begin introducing institutional support mechanisms.
- Support the codification of water rules and settlement of tenure rights, where appropriate, to create the basis for long-term development of the systems.
- Increase in-country capacity to support appropriate spate irrigation development through guidelines and through training curricula (as part of national education programmes), be it in engineering, river management, agronomy, support services for livestock, or drinking-water system development in arid areas.
- Develop and document a variety of approaches as appropriate – improved diversion, soil bunding, gabion diversion, command area management and in-field soil moisture management. In general, take a river management approach to diversion.
- Develop and improve understanding of practical approaches to favour and not obstruct groundwater recharge in spate irrigation, looking at the impact of low-recharge weirs and water-spreading scenarios.
- Stimulate farmer-based research in agronomy, agroforestry and post-harvest technologies and promote further exchange of experiences and seed materiall
- Invest in local spate irrigation systems, using a broad spectrum of techniques oriented towards farmers’ practices. Ensure that existing water distribution rules are observed and risks of sedimentation and undue flood damage are manageable, in this case using risk assessment by farmers, rather than engineers’ concerns about liability.
- Invest to improve command area management and local moisture conservation through improved field structures and livestock restocking.
- Invest in the general economic infrastructure of spate areas: improve road access and the availability of earth-moving equipment and strengthen economic infrastructure such as marketing, agronomic and livestock services and the processing of special crops (oilseed, clusterbean).
IFAD case study
The Sudan: Gash Sustainable Livelihoods Regeneration Project (2004-2013)
This project aims to regenerate the livelihoods of 67,000 poor households in and around the Gash delta through infrastructure rehabilitation and reforms in land and water governance. In so doing, it seeks to realize the full benefit of downstream pastoralist rangelands and to achieve efficient, equitable and sustainable operation of the existing Gash River spate irrigation scheme, as well as its integration into the local economy.
- combine investments in the reform of land and water governance, rehabilitation of upstream river protection, scheme irrigation and drinking water infrastructure, and range management.
- resolve land issues in advance of irrigation reconstruction works.
- strengthen farmer water user associations to assume responsibility for spate-irrigation canal operation and maintenance (O&M), including cost recovery.
- modify the current land and water lottery system to allocate multiseasonal fixed plots, providing security of wetted land tenure within the spate irrigation scheme.
- increase leaseholds to the economic minimum size of 3 feddans per year (a feddan is equivalent to 0.42 hectares), shifting the rotation from three to two years.
- implement land tenancy reform through clear regulations governing tenancy registry books.
- devolve enforcement of land and water governance arrangements to farmers’ organizations and financially viable water user associations.
- support multiple-use systems.
- reconstruct intake weirs on the Gash River and distribution works on secondary canals.
- protect Kassala City and existing irrigation infrastructure through Gash River training and regulation.
- rehabilitate public drinking-water infrastructure.
- reopening for spate irrigation of 76,000 of the targeted 240,000 feddans
- examination of five tenancy books (one per irrigation block) and registration of the bulk of a total of 56,000 tenants
- settlement of claims and disputes by the ‘land courts’ and respect for the settlements
- marginal rise in the productivity of sorghum (8 per cent)
- increase in fodder production on the range (60 per cent)
- restocking of herds and growth of 12 per cent
- increase in milk production of 62 per cent
- 80 per cent coverage of food requirements
These improvements and their gross margins are not enough to cover self-financed O&M. This would require a dramatic shift towards high-value cash and market crops, a choice not easily made by the semi-nomadic, pastoralist Hadendowa, who represent the majority of tenants in and around the spate irrigation scheme.
Topic sheet author: Frank van Steenbergen (MetaMeta)
Peer reviewed by: Abraham Haile Mehari (MetaMeta)
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