Irrigation expansion could feed 800 million more people

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

Agriculture, which accounts for 90 percent of global water use, is the biggest driver of water scarcity worldwide. In a recent study published in Scientific advances, Paolo D’Odorico, professor of environmental science, policy and management, and doctoral candidate Lorenzo Rosa investigate water scarcity in the world’s agricultural lands, assess various geographic factors, and present the data on high-resolution maps.

D’Odorico and Rosa make distinctions between physical and social restrictions on access to water in the analysis. “While some scarcity is associated with insufficient availability of fresh water in the physical environment, economic water scarcity has been defined as the physical availability of renewable water resources, but with a lack of economic and institutional capacity that limits the capacity 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 plenty of 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 obtained through expanded irrigation.

The results suggest that there is enough water available locally to expand irrigation to more than 140 million hectares of agricultural land. However, for socio-economic reasons, irrigation infrastructure is not currently available for much of this farmland. The authors point out that such expansion of irrigation could have significant implications in a changing climate. “A sustainable expansion of irrigation on economically low water lands could be an important adaptation strategy to climate change, contributing to a more reliable and resistant crop production,” says D’Odorico.

The authors also find that two-thirds of the land suitable for irrigation expansion is in sub-Saharan Africa, eastern Europe, and central Asia. In these regions, the expansion of sustainable irrigation could boost food production and feed an additional 800 million people.

The study was carried out in collaboration with a team of scientists from the Politecnico di Milano and the University of Amsterdam.