Asia must reform its water use to feed 1.5 billion extra people by 2050, says a new report.

一项新调查显示，亚洲必须赶在2050年以前进行用水改革以供给新增加的15亿人口。

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Asian farmers need to modernise their irrigation methods

The authors warn that without big changes to irrigation many nations will have to import food.

The report says that 94% of suitable land in South Asia is already being used for growing food.

According to their computer model the continent could obtain three quarters of the additional food it needs with better irrigation systems.

The report will be presented on Tuesday to the World Water Week conference in Stockholm.

The study was carried out by the International Water Management Institute and the United Nations Food and Agriculture Organization (FAO).

The researchers warn that some developing nations will have to import more than a quarter of the rice, what and maize²（玉米） they will need by 2050 and that this prospect³ will be politically risky⁴.

They outline three options for meeting the food needs of Asia's population.

The first is to import large quantities of cereals（谷类食品） from other regions, the second to improve and expand "rain-fed" agriculture and the third is to focus on irrigated⁵ farmlands.

Politically risky

The report warns that the first option is too politically risky and the second is impossible as suitable land is already in use in many areas.

Lead author Aditi Mukherji of the International Water Management Institute said: "Today, the option of expanding irrigated land area in Asia to feed a growing population is becoming increasingly problematic due to land or water constraints⁶（系统规定参数）."

The scenarios⁷ presented in the report do not factor in climate change which is likely to make rainfall more erratic（不稳定的，奇怪的）.

The report recommends modernising the region's large scale irrigation systems which rely on surface water but have fallen into disrepair（破损，失修） through lack of investment.

Another suggestion is for governments to help individual farmers use cheap pumps to extract ground water for irrigation.