Overview

• Researchers from IIT Gandhinagar and the University of Arizona reconstructed 1,300 years of streamflow and found a sharp, sustained drop since the early 1990s.
• Two unprecedented seven-year droughts — 1991–97 and 2004–10 — rank among the longest in the basin’s history and exceed the severity of earlier mega-droughts.
• The study ties the decline mainly to weaker monsoons linked to Indian Ocean warming and aerosol pollution, with additional stress from heavy groundwater pumping and long-term glacier loss.
• More than 600 million people depend on the basin, and historically low flows in 2015–2017 disrupted drinking water, irrigation, power generation and navigation for tens of millions.
• Most global climate models fail to reproduce the observed drying trend, prompting calls for urgent water-governance reforms, improved monsoon forecasting, sustainable groundwater management and stronger transboundary cooperation.