The productivity of irrigated land is approximately three times greater than that of rainfed land. Beyond that global fact, there are many more reasons for highlighting the role of water control in agriculture. Investing in irrigation development provides insurance against erratic rainfall and stabilizes agricultural output, boosting crop productivity and allowing farmers to diversify. This translates into increased and less volatile farm incomes.
In turn, a more predictable and stable production system has a positive effect on providers of services to the sector, increasing the non-farm multiplier effect of the investment. In addition, investment in water development increases the value of land. Small-scale water collection, irrigation and drainage works implemented with local labour are economically viable, and once the basic infrastructure has been put in place with public funding, further private investment also becomes viable. Additional indirect effects of investing in water development include improved nutrition throughout the year, a more active market in rural labour; reduced out-migration, and reduced agricultural pressure on marginal land.
Regional perspectives. FAO says the issues and challenges facing water control in agriculture vary among regions according to their socio-economic and agro-climatic conditions. It has reviewed three regions of the world - Africa, the Near East and small island developing states - where agricultural water control has been critical and considered their future prospects.
Africa. Sustainable social and economic development in Africa is necessarily based on development of its agricultural sector, which is major source of livelihoods for 70 percent of its population and 80 percent of its poor. Yet, only seven percent of the arable land area in Africa, and barely four percent in Sub-Saharan Africa, is irrigated. In contrast, irrigated land accounts for 38 percent of arable land in Asia. As a result, sub-Saharan Africa uses less than three percent of its water resources compared to 20 percent in Asia. Given that one third of the population of Sub-Saharan Africa is undernourished, and that its current population of 700 million is expected to reach 1.2 billion in 2030, the opportunities to improve the livelihoods of rural communities through water control are clear.
The New Partnership for Africa's Development (NEPAD) has identified water control as the first pillar to sustain development in the context of the Comprehensive Africa Agriculture Development Programme (CAADP), and has identified investment in water programmes as a priority. The CAADP estimates that as part of a wider set of measures to promote agricultural and rural development, an annual investment of around US$2 billion would be needed to boost irrigated agriculture in Africa.
In its recent report Our common interest, the Commission for Africa underscored the importance of investing in water control and management, a view that is also strongly subscribed to by the African Union. To complement these initiatives, the African Development Bank and the European Union have launched water facility funding mechanisms to increase investment in rural water management.
The Near East. An estimated 65 percent of the Near East's population is food insecure. It is the world's driest region and acute water scarcity and shortage are widespread. The region has the lowest per capita water endowment in the world, with 16 countries below the threshold of 500 cubic meters a year, compared to a global average of more than 7,000. Given the arid and semi-arid climates of the region, irrigation has always been the mainstay of the agricultural sector, and high temperatures combined with low pest infestation have favoured the production of irrigated crops. However, use of the region's limited renewable water resources and non-renewable groundwater resources of the region has reached technical and natural limits, posing new challenges for irrigated agriculture.
Small island developing states. The Small Island Developing States (SIDS) also face serious water management challenges. Many islands have very limited surface water catchments as well as vulnerable aquifer systems, which are prone to over-exploitation and saline intrusion. Population pressure on these limited resources is such that extreme measures are required to conserve what viable groundwater resources remain in place for critical human needs and food production. Improved assessment and monitoring of available resources is critical, along with enhanced institutional capacities to micro-manage strategic aquifer reserves and surface water catchments.
But the nature of the agriculture sector in many SIDS also poses problems. Agriculture is characterised by a dual system with typically large estate commercial plantations, with poorly organized smallholders occupying more marginal areas of inherently lower productivity. Typically, these small island states require investment in rehabilitation of on-farm and small scale irrigation schemes, including adoption of localized irrigation technologies for high value produce.
Strategic issues: Competition for water. In the absence of substantial claims for water from other sectors, and understanding of its environmental impacts, irrigated agriculture has been able to capture large volumes of freshwater. Today, agriculture represents 69 percent of all water withdrawal in the world, and this percentage rises above 90 percent in some arid countries. As such, agriculture has acted as a residual user of freshwater. The situation is changing as population increases and more and more countries face water shortages. By 2030, over 60 percent of the population will live in urban areas, claiming an increasing share of water abstraction.
There is an urgent need, therefore, to reconcile water demands for maintaining ecosystem functions and for producing food. Finding this balance is particularly important in developing countries, where agriculture and the natural environment are often the principle potential "growth engines", and the key to alleviating poverty and reducing hunger.
Of all freshwater use sectors, agriculture in most cases shows the lowest return on water in economic terms. As the stress on water resources increases, competition grows between agriculture fighting to retain its water allocations and cities needing to satisfy the needs of their rapidly growing populations. Water stress and the pressing need to renegotiate inter-sectoral allocations are usually factors that force changes in the way water is managed in agriculture. Declining water quality adds to the stress on supply. In developing countries, water diverted to cities is often released after use without adequate treatment. In arid areas, return flow from agriculture itself and multiple reuses of water lead to a rapid degradation in quality. In many islands and coastal areas, the development of tourism adds to the burden on scarce water resources, but it also bring new market opportunities for diversified and high value production, including fresh vegetables and fruits.
The scope and need exist therefore for rapid increase in agriculture's water productivity. Carefully designed water management strategies, associated with programmes aiming at improving the efficiency and productivity of water use need to be put in place. Pressurized irrigation conveyance systems, associated with localized irrigation technologies and the promotion of high return agricultural produces should be part of such strategy. Systematic collection, treatment and re-use of urban wastewater for agricultural production, associated with the development of enhanced monitoring, health protection and education programs for wastewater reuse in agriculture offer new opportunities for irrigation in conditions of water scarcity.
Evidence shows that the poverty-reducing impacts of irrigation-related interventions are larger when they are implemented in an integrated framework - for example, integrated approaches for managing surface water and groundwater (conjunctive use, developing systems that allow multiple uses of irrigation water, new investments in improving irrigation infrastructure and irrigation management, and provision of inputs, technologies, information, finance and marketing. Investments in irrigation improvement that allow for multiple uses - such as domestic water supply, irrigation, and other farm and non-farm uses of water - may have higher positive impact than separate investments. These multiple uses bring significant benefits and contributions to livelihoods, especially for poor households.
Where opportunities for irrigation with affordable technology exist, a priority option is private sector marketing of technologies. There is a range of irrigation application and resource conserving technologies, and improved production practices that offer promise for improving productivity and returns to farming by the poor. These include, for example, improved system of water delivery and control, micro-irrigation systems, adapted water lifting technologies, and on-farm water conserving technologies like zero tillage, water harvesting, or runoff farming.
The potential benefits of these innovative systems and technologies to the poor can be enhanced through initial targeted subsidy schemes for the poor, targeted training opportunities to enhance the skill and knowledge of water users, encouraging private participation in the supply chain of the needed inputs for the systems, focus on developing low pay-back period technologies; and strengthened public research on systems for further improvement.
See also: Water management: towards 2030, Raising water productivity, Improving irrigation technology and Modernizing irrigation management Published November 2005