Droughts across India's rivers occurring in sync amid climate change: Study

Climate change could be driving a co-occurrence of droughts across multiple river basins in India, causing severe water shortage and affecting food and water security, a study from the Indian Institute of Technology Gandhinagar has found.

Researchers Vimal Mishra and Dipesh Singh Chuphal said droughts and a widespread drying of rivers are becoming more common, together driving an increase in sync between droughts across several rivers.

The findings, published in the journal American Geophysical Union (AGU) Advances, have "profound implications associated with water scarcity" for the country, the team said.

The authors modelled water flow at 45 gauge stations on major rivers across India, including Ganga and Brahmaputra, from 1200 to 2012. Historical data and observations on water flow were used for the analysis.

"Drought synchronicity has increased across the Indian rivers in the present period (1850-2012) than in the (pre-industrial era) (1200-1849)," the authors wrote.

They added that "the most substantial increase in drought synchronicity occurred from the early 20th century", with about two-thirds of the gauge stations (30 of 45) registering their worst drought in the 20th and 21st centuries.

The findings provide critical insights into long-term trends in droughts across Indian rivers and "underscore the growing risk of large-scale water scarcity", the team said.

Identifying major droughts during the study period of 1200-2012 using reconstructed data, the authors found "exceptional" events in 1987, 1721, 2002, 1358, 1566, 1972, and 1694 -- most driven by a failure in monsoons and "reduced flow in several rivers in India".

For instance, the 1721-1723 drought affected three-fourths of the country and was recorded the last millennium's most severe drought during a monsoon. Ganga and the east-flowing Subarnarekha were among the most affected rivers, the team said.

Severe monsoon deficits seen in 1987 and 2002 across the Indian region -- except for parts of the Ganga and Brahmaputra basins -- resulted in droughts in over 90 per cent of the stations, the study found.

The findings are in line with those from previous studies that link climate change with droughts becoming more common and severe across the world, the authors said.

"Synchronous streamflow droughts across multiple river basins can lead to large-scale water scarcity and disruptions in food and water security," they wrote.