Water crisis: Ganges basin peak flows drop 17% per decade as rainfall shifts, threatens agri sector
Natural and human factors are driving these changes. Climate change disrupts rainfall and dries soils, while earthquakes and landslides can reshape rivers. Urbanisation, deforestation, and dams further alter river behaviour.
- Jul 7, 2025,
- Updated Jul 7, 2025 10:24 PM IST
Peak water flows in parts of India’s largest river basin are dropping by more than one-sixth each decade, a new study in npj Natural Hazards warns, threatening irrigation, drinking water, and hydropower in the world’s most populous nation. The findings reflect a broader nationwide trend of shrinking river peaks and shifting flood patterns, posing serious challenges to India’s water security.
In the western and central Ganges basin, peak outflows have declined by 17% per decade, driven by falling rainfall and drier soils, the study found.
“Our study provides updated insights into how flood behaviour is changing across India — both in terms of intensity and timing,” said Sai Kiran Kuntla at IIT-Delhi, one of the study’s authors. “Such findings help bridge the gap between scientific knowledge and actionable planning, particularly as climate change alters flood risks.”
Researchers analyzed river discharge data from 173 gauging stations across major Indian basins from 1970 to 2010. About 74% of stations showed significant declines in peak flows, alongside shifts in timing.
Peak flow measures how much water a river carries at its fullest, crucial for assessing floods and water availability.
Natural and human factors are driving these changes. Climate change disrupts rainfall and dries soils, while earthquakes and landslides can reshape rivers. Urbanisation, deforestation, and dams further alter river behaviour.
“In many Indian basins, high-flow events, including moderate floods, are critical for replenishing reservoirs, especially during the monsoon season,” said Sharad Jain, a professor in IIT Roorkee’s civil engineering department.
“These inflows are essential for meeting irrigation, domestic water supply, and hydropower needs.”
“A decline in … peak flows could therefore have implications, as it may reduce the volume of water captured during peak flow periods, especially in basins highly dependent on monsoonal runoff,” added Jain, who participated in the study.
In central India’s Narmada basin, peak flows have fallen alongside dam construction. On the drought-prone Deccan plateau in the south, monsoon peaks have dropped 8% per decade, while pre-monsoon peaks have plunged 31%.
“Peak outflows are a function of rainfall and soil moisture prior to rain,” explained Ashish Sharma, a professor at the University of New South Wales, Australia, who did not participate in the study.
“With temperatures on the rise, soil moisture is decreasing because of higher evaporation, and dry soil absorbs more water.”
Meanwhile, India’s monsoon has grown more erratic, bringing longer dry spells punctuated by short, intense storms.
“Instead of steady, moderate rainfall across the season, we now see longer dry spells broken by short, intense downpours,” said M K Roxy, climate scientist at the Indian Institute of Tropical Meteorology in Pune, who did not participate in the study.
Unchecked urbanisation is worsening the impacts. “With unchecked urbanisation, even a short spell of rain turns into a flood,” Roxy warned.
Earlier rainfall is also shifting peak river flows forward, complicating reservoir management, irrigation planning, and flood alerts.
“Our results signal a hydrologic regime that is becoming more erratic,” said Manabendra Saharia, associate professor at IIT-Delhi and co-author of the study.
“Translating these insights into updated reservoir rules, urban drainage designs, and drought-relief plans is now urgent if we want India’s water infrastructure to stay one step ahead of a changing climate.”
Peak water flows in parts of India’s largest river basin are dropping by more than one-sixth each decade, a new study in npj Natural Hazards warns, threatening irrigation, drinking water, and hydropower in the world’s most populous nation. The findings reflect a broader nationwide trend of shrinking river peaks and shifting flood patterns, posing serious challenges to India’s water security.
In the western and central Ganges basin, peak outflows have declined by 17% per decade, driven by falling rainfall and drier soils, the study found.
“Our study provides updated insights into how flood behaviour is changing across India — both in terms of intensity and timing,” said Sai Kiran Kuntla at IIT-Delhi, one of the study’s authors. “Such findings help bridge the gap between scientific knowledge and actionable planning, particularly as climate change alters flood risks.”
Researchers analyzed river discharge data from 173 gauging stations across major Indian basins from 1970 to 2010. About 74% of stations showed significant declines in peak flows, alongside shifts in timing.
Peak flow measures how much water a river carries at its fullest, crucial for assessing floods and water availability.
Natural and human factors are driving these changes. Climate change disrupts rainfall and dries soils, while earthquakes and landslides can reshape rivers. Urbanisation, deforestation, and dams further alter river behaviour.
“In many Indian basins, high-flow events, including moderate floods, are critical for replenishing reservoirs, especially during the monsoon season,” said Sharad Jain, a professor in IIT Roorkee’s civil engineering department.
“These inflows are essential for meeting irrigation, domestic water supply, and hydropower needs.”
“A decline in … peak flows could therefore have implications, as it may reduce the volume of water captured during peak flow periods, especially in basins highly dependent on monsoonal runoff,” added Jain, who participated in the study.
In central India’s Narmada basin, peak flows have fallen alongside dam construction. On the drought-prone Deccan plateau in the south, monsoon peaks have dropped 8% per decade, while pre-monsoon peaks have plunged 31%.
“Peak outflows are a function of rainfall and soil moisture prior to rain,” explained Ashish Sharma, a professor at the University of New South Wales, Australia, who did not participate in the study.
“With temperatures on the rise, soil moisture is decreasing because of higher evaporation, and dry soil absorbs more water.”
Meanwhile, India’s monsoon has grown more erratic, bringing longer dry spells punctuated by short, intense storms.
“Instead of steady, moderate rainfall across the season, we now see longer dry spells broken by short, intense downpours,” said M K Roxy, climate scientist at the Indian Institute of Tropical Meteorology in Pune, who did not participate in the study.
Unchecked urbanisation is worsening the impacts. “With unchecked urbanisation, even a short spell of rain turns into a flood,” Roxy warned.
Earlier rainfall is also shifting peak river flows forward, complicating reservoir management, irrigation planning, and flood alerts.
“Our results signal a hydrologic regime that is becoming more erratic,” said Manabendra Saharia, associate professor at IIT-Delhi and co-author of the study.
“Translating these insights into updated reservoir rules, urban drainage designs, and drought-relief plans is now urgent if we want India’s water infrastructure to stay one step ahead of a changing climate.”