Flooding in High Mountain Asia has been a continual issue for downstream communities and a growing hydropower sector. In a recent Nature Geoscience paper, scientists emphasized the threat of glacial melting and hazards in High Mountain Asia, not only to regional hydropower systems but also to food systems that billions of people rely upon.
Between 2000 and 2019, glaciers in the High Mountain Asia region lost approximately 21 billion tons of mass per year, and even the most liberal estimates of glacier mass loss predict that the glaciers will shrink by about 40% compared to 2019 volume by 2100. For context, if the amount of ice lost by the region’s glaciers each year were to cover Paris, only the spire of the Eiffel Tower would be visible. This massive volume of ice being released every year has consequences for local and downstream residents. Though the region has the potential to provide hydropower to over 350 million homes, these projects could be jeopardized by the impacts of glacial melting.
Most of the region’s planned hydropower projects — encompassing approximately 240 gigawatts or nearly half of the potential energy production — are either near or in areas that have previously had glacial lake outburst floods. These events are extremely dangerous, with the potential to damage hydropower projects and cause reservoir overflows or dam breaks that release deluges of water downstream. In 2013, the Kednarth disaster, which included the Chorabari Lake outburst, damaged at least 10 hydropower projects and killed over 6,000 people. Although the region holds great potential for hydropower energy production, the threat to the projects is both severe and imminent.
The Nature Geoscience paper — led by Dongfeng Li of the National University of Singapore — outlines different types of mountain landscape instabilities and their effects. The threats included melting and thawing of ice, slope instability, glacial lake outburst floods, landslides that cause lakes to overflow, and erosion. Each of these hazards can damage hydropower projects through rapid flows of debris or water, or by destabilizing the land through the thawing of permafrost or erosion.
Each type of hazard comes with its own specific risks to hydropower projects and downstream systems. Thawing ice causes instability in the slopes because the once solid, frozen ground is now more fluid, and thus more susceptible to erosion and slumping that could cause numerous hazards, such as landslides and rock-ice avalanches. When debris flows or melting ice or water enter glacial lakes, they can cause outburst floods. Likewise, erosion or the destabilization of permafrost can also lead to landslides that cause outburst floods. Lastly, erosion poses its own risk of debris flows or destabilization that could trigger landslides.
These hazards will only increase as climate change worsens and causes further glacial melt and permafrost thaw. Nonetheless, firm, precise predictions remain difficult because of challenges to research in remote High Mountain Asia. Due to the rugged terrain and variable distribution of snow- and ice-covered areas in the region, predicting the future responses of individual water systems to climate change is quite difficult.
A different paper in the journal Frontiers in Water details the work of NASA’s High Mountain Asia Team (HiMAT) tasked with studying the changing hydrology in the region; the authors asserted that “we lack a basic understanding of the key physical drivers on [High Mountain Asia] river flow.” This lack of understanding prompted their team to study the more specific impacts of precipitation, runoff, and snowmelt.
The models that are used to predict these factors are susceptible to large uncertainties. This uncertainty makes it difficult to plan to prevent major damage to infrastructure, including hydropower projects. While scientists understand the larger trends caused by climate change, such as increased precipitation and higher temperatures, it is still difficult to predict local patterns and create accurate models. For example, snow albedo (reflectivity) can be highly misrepresented when modeling snowmelt because there is often an assumption that there are no impurities or particles on top of the snow. According to the HiMAT article, this can lead to up to a 50% overestimation of the snow albedo. This error is significant, as the snow melt rate is five times faster at a reflectivity of 50% versus 90%.
Additionally, the precipitation patterns of the region are hard to predict because weather stations are few and far between. The variable terrain contributes to the sparse station coverage, which reduces the robustness of long-term precipitation data. Many of these stations have records too short to be very useful in assessing long-term trends. Thus, further research will be required in order to make accurate predictions about when hazards may occur in order to protect hydropower projects and downstream communities.
Not only are glacial melt and landscape hazards a concern for hydropower projects and downstream communities, but they also have a large impact on crops and the overall food system. Christine Bischel, a geographer at the University of Fribourg in Switzerland, stated that some of the agricultural issues arise in this region due to uncertain glacial flows. The main issues are irrigation and water availability, she said.
Increased temperatures cause spring to start earlier, creating worse or improved climates for certain crops. The amount and timing of water availability is crucial for crops, so shifting seasons will change irrigation patterns as well. Bischel further explained that predicting how much of the glacier will melt is challenging from year to year, which presents issues for downstream agricultural communities. Farmers must be able to adapt to the glacial water releases, and if the shifts become too great they may have to shift which crops they cultivate. This is “not their choice,” Bischel told GlacierHub. She added that sometimes people may even migrate north as far as Russia to find better places to grow their crops. She stated that the “biggest problem” is that the glaciers will “eventually disappear,” which may force even more farmers to migrate in the future.
Water demand for both energy and food is expected to increase as temperatures, evaporation from dams, and irrigation for crops increase. The higher demand for water combined with higher variability in precipitation will create challenges for water allocation in the future. One aspect of this challenge is that we currently have neither robust systems for predicting future crop production nor hydropower productivity based on changing water availability and precipitation.
Further research is needed to help protect agricultural and emerging hydropower infrastructure from the increasing risks of glacial melting and hazards such as glacial lake outburst floods. The biggest obstacle to monitoring these hazards and being prepared for climate risks is the lack of usable data due to sparse station coverage, which makes it difficult to create good models for future impacts. Covering more of the terrain to take more accurate measurements and create long-term data and modeling for these areas is challenging but necessary to ensure that both farmers and regional residents are protected from hazards that can destroy infrastructure and livelihoods.