Global Major River Basins Are Experiencing Frequent and Prolonged Drought Events

A study published in Science of The Total Environment revealed that, precipitation and potential evapotranspiration increased synchronously across 34 major river basins worldwide from 1901 to 2021. However, the dominance of potential evapotranspiration has resulted in a gradual intensification of meteorological drought.

"Meteorological drought is driven by changes in sea surface temperature, especially the El Nino Southern Oscillation or other climate indices,” said Prof. DUAN Weili from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences, corresponding author of the study.

To examine and compare meteorological droughts across 34 major global river basins, researchers employed a three-dimensional clustering algorithm that used the standardized precipitation evapotranspiration index over a 12-month period.

They found that 47% (16/34) of the basins showed a drying trend with prolonged durations of severe droughts, with the most severe drought event occurring in the Amazon basin.

In addition, although drought events occurred frequently, more than half of them were identified as short-term droughts, lasting no more than three months.

This study suggests that river basins in the tropical zone exhibit a pronounced trend towards heightened aridity, indicating a more severe drought situation, while those in the cold zone display a tendency towards increased wetness, suggesting a comparatively alleviated drought scenario.

This research offers valuable perspectives on the attributes and underlying processes of meteorological droughts across various river basins worldwide.