River flow is an important indicator of water resources available to humans and the environment. The amount of available water also depends on other factors, such as direct interventions in the water cycle or land use change. If, for example, water is diverted for irrigation or regulated via reservoirs, or forests are cleared and monocultures grown in their place, this can have an impact on river flow.

A new study, published in the journal Science, demonstrates that river flow changed systematically between 1971 and 2010. The study revealed complex patterns—some regions such as the Mediterranean and north-eastern Brazil had become drier, while elsewhere the volume of water had increased, such as in Scandinavia.

“The actual question, however, concerned the cause of this change,” says lead author Lukas Gudmundsson, senior assistant in the group led by Sonia Seneviratne, professor at the Institute for Atmospheric and Climate Science at ETH Zurich.

To answer this question, the researchers carried out several computer simulations, using global hydrological models fed with observed climate data from the period studied (1971 to 2010). The results of the model calculations closely matched the analysis of observed river flow. “This means that climatic conditions can explain the observed trends in the flow volumes,” Gudmundsson says.

Read the full article about climate change and rivers by Peter Rüegg at Futurity.