A third of the world's river sub-basins, the smallest units into which river basins are divided, will face a severe shortage of clean water by 2050, says a study published in the journal Nature Communications and led by Wageningen University , in the Netherlands, predicting a crisis that will directly impact at least 3 billion people.
The threat comes above all from pollution due to nitrogen, widely used for example in agriculture as a fertilizer, and looms large in particular in the sub-basins of Central Europe, North America, southern China and Africa.
Researchers led by Mengru Wang analyzed data from river basins globally, finding that nitrogen pollution dramatically increases the number of those at risk of scarcity when water quality is also considered: in particular, threatened sub-basins could triple in the near future.
In 2010, more than 980 river subbasins had little water, but more than 2,500 had high levels of pollution, and therefore contained little clean, usable water.
The authors of the study predict that, by 2050, this figure will rise to more than 3,060 sub-basins characterized by water scarcity in terms of both quantity and quality.
The results, therefore, underline the urgent need to address the issue of water quality in future management policies.
The researchers highlight the importance of policy makers incorporating water quality into their assessments, and the fact that many pollution control measures not directly related to rivers, such as those aimed at the agriculture sector, can however also have beneficial effects on the water resource, protecting it from pollution and scarcity.
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