Measuring how efficiently water is used in agriculture, particularly in water-scarce countries, is going high-tech with the help of a new tool developed by FAO.

The WaPOR open-access database has gone live, tapping satellite data to help farmers achieve more reliable agricultural yields and allowing for the optimization of irrigation systems.

WaPOR was presented this week during a high-level partners meeting for FAO's Coping with water scarcity in agriculture: a global framework for action in a changing climate. It allows for fine-grained analysis of water utilised through farming systems, generating empirical evidence about how it can be most productively used.

Worldwide water utilization - the majority of which is used by agriculture - has outpaced the rate of population growth for most of the last century and some regions are close to breaching viable limits.

"Water use continues to surge at the same time that climate change - with increasing droughts and extreme weather - is altering and reducing water availability for agriculture," says Maria Helena Semedo, FAO's Deputy Director-General, Climate Change and Natural Resources. "That puts a premium on making every drop count, underscoring the importance of meeting growing food production needs from efficiency gains."

WaPOR sifts through satellite data and uses Google Earth computing power to produce maps that show how much biomass and yield is produced per cubic meter of water consumed. The maps can be rendered at resolutions of as little as 30 to 250 meters, and updated every one to ten days.

FAO's team of information technology and land and water officers has designed WaPOR - through a $10 million project funded by the Government of the Netherlands - to cover Africa and the Near East, with a focus on key countries that are or are projected soon to face physical or infrastructural water scarcity.

The continental level database is online as of today, while country level data will be made available in June for Benin, Burundi, Egypt, Ethiopia, Ghana, Jordan, Kenya, Lebanon, Mali, Morocco, Mozambique, Rwanda, South Sudan, Syria, Tunisia, Uganda, West Bank and Gaza Strip, and Yemen. Even more detailed data will come online in October, starting with pilot areas in Lebanon, Ethiopia and Mali.

WaPOR measures evapotranspiration, a key phase in the natural water cycle consisting of water that directly evaporates into the atmosphere and water that returns to the atmosphere after moving through a plant and emerging as vapor exuded by foliage. Evapotranspiration thus provides a direct measure of the water consumed by a crop during a growing season and, when related to the biomass and harvestable crop yield, allows for calculating the crop water productivity.

More about the WaPOR tool,please visit FAO site