A study has found that foreign-owned agricultural projects on leased land in central and eastern Africa are more likely to end up in conflict with other users when their water sources are rivers, lakes and acquifers.
More than half of the water needed for leased land investments in the region use such sources, known as blue water, instead of precipitation stored in soils (green water), according to a paper published in the Proceedings of the National Academy of Sciences at Lund University.
“Even if the most efficient irrigation systems were implemented, 18 percent of land acquisitions, totaling 91,000 [hectares], would still require more than 50 percent of [their] water from blue water sources,” according to the paper. These “hotspots”, as the paper calls leases on farmland with these requirements, are most at risk of contributing to regional constraints, environmental and social conflict, particularly when freshwater access is already affected by overconsumption.
Using crowdsourced land-deal Land Matrix data on 121 investments producing food, fuel and forestry crops in central and eastern Africa, researchers also found that water-intensive agricultural and forestry crops like sugarcane, jatropha, rubber cotton and eucalyptus were most commonly planted by foreign investors. Of these investments, only nine relied on blue water for 75 percent of their water use, but 33 relied on it for 50-to-75 percent of irrigation and 46 used it for between 25 and 50 percent of irrigation. Thirty-three deals examined used less than 25 percent blue water, the researchers calculated using a water-use to maximum-yield index.
The paper said crop choice, based on price, demand and calorie content, should also take into account local blue and green water demand.
“Our research can perhaps lead to foreign investors showing greater consideration for how much water is necessary, in relation to how much water is actually available,” said Emma Li Johansson, one of the paper’s authors. “Hopefully, the results can serve as the basis for documents that regulate the water consumption of large-scale farming companies.”