Irrigation expansion could feed 800 million more people

Percentages represent fraction of the global cultivated area in each category. Shading indicates croplands affected by blue water scarcity (BWS) that can be sustainably irrigated with deficit irrigation. These areas are then reclassified as suitable for sustainable irrigation [i.e., with no blue water scarcity (NO BWS)], considering different deficit irrigation scenarios. Lack of irrigation in these areas is interpreted as agricultural EWS.
Credit: University of California – Berkeley

Water scarcity, a socio-environmental threat to anthropogenic activities and ecosystems alike, affects large regions of the globe. However, it is often the most vulnerable and disadvantaged populations that suffer the severest consequences, highlighting the role of economic and institutional factors in water scarcity. In this way, researchers generally consider not only the physical constraints but socio-economic determinants as well.

Agriculture, which accounts for 90 percent of global water use, is the largest driver of water scarcity worldwide. In a recent study published in Science Advances, environmental science, policy, and management professor Paolo D’Odorico and PhD candidate Lorenzo Rosa investigate water scarcity over global agricultural lands, assessing various geographical factors and presenting the data in high resolution maps.

D’Odorico and Rosa draw distinctions between the physical and societal constraints to water access in the analysis. “While some scarcity is associated with insufficient freshwater availability in the physical environment, economic water scarcity has been defined as renewable water resources being physically available, but with a lack of economic and institutional capacity that limits the ability of a society to use that water,” says Rosa.

Using data intensive computer models, the researchers quantify the water currently provided to crops. They determine the optimal amount of water needed to grow these crops under normal conditions with ample water. Then using hydrological models, the authors compare water demand with availability, to measure scarcity and determine the regions of the world where additional water could be made available through expanded irrigation.

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