A new study of more than 10,000 rivers worldwide found that 27% have flow trends that don't match the precipitation they receive. Among those, 40% are getting more rain and snow than 70 years ago yet still trending toward lower water levels. Researchers point to increased evaporation and more frequent rainfall extremes as likely drivers, meaning precipitation totals alone can't predict river flow. Understanding what actually controls river flows matters for water supply planning, agriculture, and hydropower. As the climate changes, infrastructure decisions based only on rainfall data will miss real risk. The study is published in Geophysical Research Letters and covers 1951 to 2020.
