High mountain Asia hydropower systems threatened by climate change

The Himalayas and neighbouring mountain ranges (or High Mountain Asia), the planet's largest ice systems outside the polar regions, have the world's largest undeveloped hydroelectric potential and are seeing numerous dams and reservoirs under construction or planning.

However, climate change is destabilizing landscapes and threatening numerous hydroelectric projects according to a new study led by researchers at the National University of Singapore (NUS).

In recent years, significant and far-reaching impacts on hydropower projects (HPPs) have been reported due to climate-related mountain hazards in the Himalayas.

In February 2021, an avalanche hit a valley of Himalayan glaciers in the Chamoli district of Uttarakhand, India, and as a result, accelerating debris flows along with the water turned into devastating floods, wiping out two hydroelectric projects, including one under construction.

Dr. Dongfeng Li, the lead author of the study and a researcher at the Department of Geography in the NUS College of Arts and Social Sciences, said: "Our study was stimulated by these recent HPP faults in the Himalayas. We think that such mountain hazards could be related to climate change and therefore initiated a project to systematically investigate the impacts of climate-driven hazards on hydropower dams and reservoirs across High Mountain Asia.”

Conducted in collaboration with international scientists from the UK, Nepal, Australia, the Netherlands, Canada, Switzerland, China and Kazakhstan, the study offered recommendations on climate-resilient hydropower systems in high mountain areas. It was published in Nature Geoscience on June 23, 2022.

The study, which collected and examined data on glaciers, permafrost, typical mountain hazards, and related hydroelectric kills in the region from the 1960s to the present, found that global warming-induced melting and thawing of ice systems are severely altering volume and time. of water supplied from the high mountains of Asia, negatively affecting the downstream food and energy systems that billions of people rely on.

The construction of more reservoirs designed to regulate the flow and produce hydroelectric power is a fundamental part of the strategies to adapt to these changes. However, the study revealed that these projects are vulnerable to a complex set of interactive processes that destabilise landscapes throughout the region.

These processes, which vary in severity and rate of change, include glacial retreat and calving, permafrost thawing and associated landslides, rock and ice avalanches, debris flows, and glacial lake outburst flooding and landslide-dammed lakes. of Earth. The result is the mobilization of large amounts of sediment that can fill reservoirs, cause dam failures and degrade electrical turbines.

To minimize the adverse impacts of climate-driven mountain landscape instability on dams and reservoirs, the team identified the following future actions. First, maps of the distribution of paraglacial zones (or zones recently exposed after glacial retreat), sediment yield, and hazard susceptibility should be produced that better delineate current and future unstable landscapes and regions. prone to erosion, particularly for HPP hotspots. Policy development regarding maintenance of existing HPPs and planning for new HPPs should be guided by such hazard and risk maps.

Second, sediment issues must be seen as a critical consideration for hydropower development. The study's second author, Professor Xixi Lu, from the NUS FASS Department of Geography, explained: "When planning future reservoirs, storage capacity design should consider potential storage losses associated with increased sediment loads. due to climate change and provide additional storage to deal with climate-related hazards.”

Third, monitoring, forecasting and early warning systems need to be further developed and implemented. "We suggest improving the monitoring of glaciers, permafrost, unstable slopes, glacial lakes, erosion, and sediment production using a variety of approaches, such as remote sensing and ground-based observations," emphasized Dr. Tobias Bolch, one of the co-author and researcher at the University of St Andrews in the UK.

Third, surveillance, forecasting and early warning systems must be further developed and intensified. We can improve the monitoring of glaciers, permafrost, unstable slopes, glacial lakes, erosion, and sediments by using approaches such as remote sensing and ground-based observations.

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