Mustard fields, Ladakh – India. Photo: Alex Treadway/ICIMOD.

Millions of farmers in South Asia depend on meltwater from the Himalayas. Melting glaciers, rainwater and groundwater allow farmers downstream to irrigate their crops. Using a novel model, an international team of researchers determine for the first time how great the impact of melting glaciers will be on the downstream water supply in the future, and how the pressure on different water sources will increase. The results was published on 19 May in Nature Climate Change.

The Himalayas are a climate change hotspot: areas located at high altitude heat up faster than the rest of the planet. As a result, glacier ice is melting which affects the millions of farmers downstream who are partly dependent on glacial meltwater. In addition to climate change, an increasing demand for water – due to expanding farmland to feed a growing population – plays an important role in determining future water shortages.

“Using a novel model, we were able to calculate very precisely where and when water will be needed in the future, and where it will come from – rainwater, groundwater, or meltwater from the mountains,”

– Arthur Lutz, hydrologist at Utrecht University and lead author of the study.

The model integrates the effects of climate change and increasing water demand. Lutz: “The model incorporates changes in snowfall and glaciers in the high mountains, as well as changes in water use for downstream agricultural crops.” This allowed the scientists to see exactly what the climate and socio-economic effects would be on South Asia’s water supply in the future. They were also able to see how the pressure on different water sources (meltwater, rainwater, groundwater) will change.

What exactly will change? Global warming causes glaciers to start melting earlier in the year, just when crops are being sown. This is favourable, but later in the year, when crops need the most water, there is less meltwater. Climate change also makes rainfall more irregular, so farmers have to pump more groundwater later in the year to compensate for a shortage of rain and meltwater. The effect is exacerbated by expanding farmland needed to feed more people. “Therefore, a lot of extra groundwater has to be pumped up, more than can be replenished,” says Hester Biemans, researcher at Wageningen University and co-author of the new study. “This is not sustainable in the long run.”

“This study uses a unique cryosphere–hydrology–crop model that projects how sources of water supply such as meltwater and groundwater will shift in the future in the Indus, Ganges and Brahmaputra basins. The results of this study will help us to better plan agriculture  and agriculture water management, which is esentially important to avoid water scarcity and the depletion of groundwater resources.”

– Arun Shrestha, Senior Climate Specialist at the International Centre for Integrated Mountain Developement.

The results of this study can be used for targeted climate adaptation and sustainable water management in this geopolitically complex region. This could include increasing water storage capacity in large and small reservoirs, using water more efficiently in agriculture, and switching to different crops or different sowing dates. Such measures can help reduce the pressure on meltwater and groundwater resources. The researchers will continue their calculations to determine the best combination of measures.

For any further information contact:

ICIMOD: Neraz Tuladhar, Media Officer media@icimod.org

Wageningen University & Research, Hester Biemans press@wur.nl

About Wageningen University & Research

The mission of Wageningen University & Research is “To explore the potential of nature to improve the quality of life”. Under the banner Wageningen University & Research, Wageningen University and the specialised research institutes of the Wageningen Research Foundation have joined forces in contributing to finding solutions to important questions in the domain of healthy food and living environment. With its roughly 30 branches, 6,800 employees (6,000 fte) and 12,900 students, Wageningen University & Research is one of the leading organisations in its domain. The unique Wageningen approach lies in its integrated approach to issues and the collaboration between different disciplines.

About Utrecht University

We are Utrecht University. The place where new partnerships and cross-pollinations have been taking place since 1636. Deeply rooted in the city of Utrecht, we operate internationally. Beyond the boundaries of disciplines we research, teach and share knowledge and insights that provide the building blocks for tomorrow.

Sharing science, shaping tomorrow.

About ICIMOD

The International Centre for Integrated Mountain Development (ICIMOD) is an intergovernmental knowledge and learning centre working on behalf of the people of the Hindu Kush Himalaya (HKH). We are based in Kathmandu, Nepal and work in and for our eight regional member countries – Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan. We work to improve the lives and livelihoods of men, women, and children of the HKH and protect mountain environments and cultures. The knowledge we create and share helps the people of the HKH become more resilient, make the most of new opportunities, and prepare for change. Our work strengthens regional cooperation for conservation and sustainable mountain development.

https://www.icimod.org/

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