River subbasins more depleted than official figures show

Published online 9 April 2024

Waste from sewage systems and increased agricultural production are causing  severe water scarcity in almost a quarter of subbasins around the world

Mohammed El-Said

Maryna Strokal

A new study revealed that while the number of severely depleted river subbasins stood at 984 out of the 10,226 subbasins around the world in 2010, the number more than doubles to 2,517 when taking into account the quality of water, not just the quantity. The study, published in Nature Communications, also predicts the number to triple in 2050 to 3,061 when using the clean-water scarcity assessment that considers high nitrogen pollution levels in the water instead of the classical water scarcity assessment, putting an additional 3 billion people at risk. The study is particularly important in the Middle East and North Africa, where 83 % of the population has very high-water stress, according to a report by the World Resources Institute.“Our results stress the urgent need to address water quality in future water management policies for the Sustainable Development Goals,” the authors wrote. The main causes of nitrogen pollution in water are the expansion of agricultural production, as well as human waste generated by sewage systems,” said the study’s lead researcher, Mengru Wang, who is an assistant professor of ecosystems at Wageningen University in the Netherlands.Wang added that the dominant source of nitrogen in rivers varies, but the main source of nitrogen is human waste resulting from rapid urbanization, and the connection of sewage systems to rivers. This gets worse if wastewater treatment is poor in developing countries.    Dietrich Bartelt, a member of the Board of Experts of the Global Institute for Water, Environment and Health in Switzerland, told Nature Middle East that the approaches currently used in the Middle East and North Africa to deal with the problem of water shortage are based on a very narrow perspective. He argued that countries in the region must adopt better water practices in agriculture and integrated water resources management. They must also strengthen water infrastructure through adopting more natural solutions and green infrastructure, such as restoring wetlands, mangroves and forests that improve water quality and enhance our resilience in the face of drought, in addition to saving money spent on water treatment.