Water shortages affect a third of the global population but solutions to the problem abound, says a major report published today (21 August).
The Comprehensive Assessment of Water Management in Agriculture was launched at the World Water Week meeting in Stockholm, Sweden.
It urges policymakers to take radical action to make water supplies sustainable.
The report says a quarter of the world's people live where water is naturally scarce and tends to be over-used. This causes groundwater levels to decline and rivers to dry up.
The report calls for awareness that there is no more 'new' water for such scarce regions, particularly in Asia and North Africa.
Another billion people live in areas such as sub-Saharan Africa where water is available but 'economically scarce' — it is inadequately distributed due to mismanagement or a lack of investment. The report says that storing more water remains a key priority for these regions.
Some 700 experts conducted the assessment over five years. Their report reviews the impacts of various water management strategies adopted over the past 50 years and recommends ways of easing water shortages.
It says agriculture uses up to 70 times more water than domestic uses such as drinking, cooking or bathing. But solutions exist that would allow agriculture to feed an extra 2-3 billion people, using only half the amount of water currently expected.
The report highlights the importance of low-cost technologies, such as treadle pumps, that could increase poor farmer's access to water resources. Water could also be used more efficiently through better irrigation, and by efforts to develop higher-yielding crops.
Africa's savannahs — where agriculture depends on variable rainfall — are singled out as having the greatest potential for making better use of limited water supplies.
The report also says urban wastewater could be a productive resource if health risks linked to its use are addressed.
David Molden of the International Water Management Institute, who led the study, said a key trade-off was with the environment. He warned against solutions that would further harm the environment, such as building more dams, diverting more water to agriculture, or clearing more space for rain-fed crops.