By Carolyn Fry

Irrigation will play a key role in producing food to feed the 1.5 billion more people who will live in Asia by 2050. This is the main finding of the report Revitalizing Asia's Irrigation: To sustainably meet tomorrow's food needs, published this month by IWMI and FAO. The authors use numerical modelling to assess the various options Asia has for meeting its future food requirements. They suggest increasing yields from rain-fed agriculture will be important, but note this sector faces increasing risk from climate change. They find there is great potential to boost yields from irrigated agriculture, particularly in South Asia. However, they conclude the sector first needs revitalizing to enable it to function more effectively.

Compiled by lead authors Aditi Mukherji of IWMI and Thierry Facon of FAO, and funded by the Asian Development Bank, the report is the result of discussions between experts from many institutions, including participants of the workshop Trends and Transitions in Asian Irrigation: What are the Prospects for the Future, held at the FAO Regional office for Asia and the Pacific in Bangkok, Thailand, between January 19th and 21st this year. The first publication of the KnowledgeHubs regional network, it assesses past trends and emerging challenges for Asian irrigation, discusses what drives changes within the sector, considers the different methods Asia could employ to feed its swelling population and outlines the best strategies for achieving future food production targets.

Asia's extensive irrigation infrastructure is not currently being used to its full potential because the conditions that prevailed when it was installed no longer exist. Back in the 1960s and 1970s, with Asia predominantly rural, farmers mostly grew cereals such as rice and wheat. They relied on large-scale, centrally managed supply-driven irrigation schemes to provide their water and secure their livelihoods. Today, however, many have diversified to grow more fruit and vegetables in response to changing dietary demands. "These kind of farming methods need more flexible and responsive management that delivers water on demand," says David Molden, Deputy Director General for Research at IWMI and one of the report's authors.

With yesteryear's large irrigation schemes unable to meet such needs, farmers have installed millions of groundwater pumps across Asia to secure their own supplies. They have successfully increased food production while investment in major irrigation schemes has been declining. This is an achievement, given that official efforts to reform the old systems, by passing responsibility for operations to farmers' associations, have been largely unsuccessful. There have been negative side effects, however. With no regulation of independent water-supply operations, levels have dropped so much in some places that they have disrupted natural water flows and the habitats they support. Past large-scale irrigation developments, coupled with mono-cropping and high use of fertilizers, have also taken their toll on the environment.

The authors suggest Asia needs several strategies for improving irrigation if it is to achieve food goals in different places and under the varying economic, political and geographic conditions that exist across the continent. They put forward five strategies for helping irrigation perform to its full potential and deliver our future food needs, while safeguarding the environment. These are: to modernize existing large-scale schemes to meet modern farming needs; emulate farmers' initiatives where they have successfully employed their own irrigation methods; improve on existing reforms by engaging the private sector in irrigation; boost knowledge through training; and invest in other sectors where such funds may indirectly influence irrigation.

Investments in irrigation are closely linked to food and energy prices. The authors note that, with food and energy costs forecast to rise in future, there is renewed interest in investing within the sector. However, they warn that only innovative methods will be able to reverse the degradation that has resulted from years of neglect. "There's scope to double the productivity from irrigated lands in Asia," says Molden. "But to do so we'll need more reliable irrigation systems that provide a good service to farmers, along with better soil health and improved varieties of seeds that are resistant to pests." If Asian irrigation can improve, within the uncertainties of rainfall and runoff presented by climate change, it will play a vital role in preventing Asia's future population from going hungry.