Climate change threatens long-term water security in Uttarakhand’s kosi basin: IIT Roorkee study

Roorkee: Climate change could significantly undermine long-term water security in Uttarakhand’s Kosi River Basin, with rising temperatures, declining groundwater recharge and increasing drought risks threatening agriculture, drinking water supplies and fragile Himalayan ecosystems, according to a new study by researchers from the Indian Institute of Technology (IIT) Roorkee and the G. B. Pant National Institute of Himalayan Environment (GBPNIHE).

The study, published in the journal Theoretical and Applied Climatology, was conducted by Dr. B. Das and Dr. S. Sen of IIT Roorkee along with Dr. Sandipan Mukherjee of GBPNIHE, Kosi.

Using the Soil and Water Assessment Tool (SWAT) integrated with projections from five leading global climate models, the researchers assessed how climate change could alter the hydrology of the Kosi River Basin through the 21st century.

The findings project a steady rise in temperatures under all future climate scenarios. Peak temperatures, currently averaging around 38.4°C, could increase to about 41.6°C under a moderate-emissions scenario and nearly 43.2°C under a high-emissions scenario by the end of the century.

Both maximum and minimum temperatures are expected to rise significantly, accelerating evaporation and reducing overall water availability.

Despite uncertainties surrounding future rainfall patterns, the study estimates that total water yield in the basin could decline by 4–7 percent by 2100.

Higher temperatures are projected to increase evapotranspiration by nearly 13 percent, while groundwater recharge may fall by more than 20 percent. Surface runoff, however, could rise by around 20 percent, causing rainwater to flow more rapidly across the landscape instead of replenishing groundwater reserves.

“The study highlights a critical shift in the hydrology of Himalayan catchments, where warmer temperatures are expected to intensify evapotranspiration and reduce groundwater replenishment.

As mountain communities depend heavily on springs and local water sources, proactive adaptation measures and science-based water management strategies will be essential to enhance resilience against future climate and drought risks,” said Dr. I. D. Bhatt, Director, GBPNIHE.

The researchers also warned that the basin is likely to experience more frequent and prolonged droughts in the coming decades. Such changes could adversely affect springs, wells, agricultural productivity and local water resources that sustain communities across the Kumaon region.

Highlighting the broader significance of the findings, Prof. Kamal Kishore Pant, Director of IIT Roorkee, said, “Climate change poses one of the most significant challenges to water security in mountain ecosystems.

Studies such as this provide vital scientific insights for developing evidence-based policies and adaptation strategies that can help safeguard water resources, livelihoods and ecological sustainability in the Himalayan region.”

The researchers recommended a range of proactive adaptation measures, including watershed management, spring rejuvenation, soil and water conservation, enhanced groundwater recharge and nature-based solutions to strengthen the resilience of the Kosi River Basin against the growing impacts of climate change.