Colin Chartres the International Water Management Institute‘s director general writes Invest in water for farming, or the world will go hungry.  In SciDev.net he writes:

The world’s population is projected to grow from 6 billion to 8.5 billion by 2030 and unless we change the way we use water and increase water productivity — ie. produce more ‘crop per drop’ — we will not be able to feed them. That is the conclusion of the IWMI’s recent Comprehensive Assessment of Water Management in Agriculture and its book, Water for Food, Water for Life, which drew on the work of 700 scientists.

While I agree that increasing agricultural water productivity is important, I think an underappreciated message of the CA (which is available online) is that globally we need to increase ecological water productivity.

A focus solely on agricultural production is likely to continue to cause declines in other valuable ecosystem services, sometimes to the extent that they outweigh any benefits gained from increases in agricultural production (See Millennium Ecosystem Assessment for many examples).  Agriculture provides benefits, but it also imposes costs.  Agriculture that ignores its ecological context has lead to coastal hypoxia, dryland salinization, and land degradation.  These problems reduce other ecosystems services, such as fisheries, while also decreasing the ecosystem support for agriculture.  These problems are increasing and overall are expected to worsen due to climate and other human caused global environmental change.

The quality, quantity and reliability of water flows connect agricultural and non-agricultural ecosystems. Water is also essential to the production of agricultural and most non-agricultural ecosystem services. Where these connections are strong requires an integrated approach to the management of water across landscapes and regions to ensure the reliable production of multiple ecosystem services.  However, in many cases we currently lack the practical knowledge to effectively manage agricultural and non-agricultural ecosystems for the multiple ecosystem services that depend upon water.  This research area is relatively underdeveloped and it is critical for ensuring human well-being in an increasingly unpredictable and resource intensive world.