Ice Stupas have become a popular tool for water management in the Himalayas. But can they work in Chile?
Every winter across the Himalayas for decades, man-made reservoirs have been capturing meltwater from glaciers from streams and keeping it in the form of ice. By slowing or spraying melted water into the air, people cause it to refreeze, often in shapes called stupas, after domed Buddhist shrines that may resemble it. The snow can then thaw the following year, allowing for irrigation that supports longer growing seasons in high mountain areas.
Now, a group of Chilean engineers is trying to transfer this technology to their country’s high mountain glaciers in what they call Project Nilos. In 2021, engineers develop their first prototype in a private park in the Cajon de Maipo region south of Santiago, the nation’s capital. The area was chosen because of the access granted to the Maipo, a glacier-fed river that descends from the Andes and provides fresh water to Santiago and the surrounding area. During the winter of 2021 in the Southern Hemisphere, their prototype collected 550,000 kilograms of ice that melted in just under two months. While smaller than the Himalayan reservoirs, it provides an early proof of concept.
The effort caught the attention of University of Pennsylvania researcher Christina Lyons, who read about the project while doing anthropological research with indigenous Mapuche communities and their relationship to the surrounding glaciers in their ancestral territory, Wallmapu, known administratively as the Araucanía region of southern Chile.
“I was completely intrigued by this idea,” she said in an interview with GlacierHub, noting that the distinct south-to-south transfer of knowledge between the Himalayas and Chile was what first set her apart. “I was really interested in this technology, what it could do and how it was framed.” Lyons began accompanying the engineers, publishing a paper analyzing the unique social and political context of the Nilus project earlier this year.
Satellite imaging dates the construction of Himalayan ice reservoirs to at least the 1960s. Sometimes called “artificial glaciers”—a catchy term but scientifically imprecise, since they don’t accumulate ice long-term or move across the land—these reservoirs reduce glacial meltwater losses by taking advantage of repeated freeze-thaw cycles in arid, cold environments. Unlike lakes, which freeze from top to bottom, ice reservoirs freeze from the bottom up. By engineering a slow trickle of meltwater from the mountains—whether by creating a series of loose ladders, redirecting the water to a shaded location with a large area, or by sending it into tubes that spray it into the surrounding air—glacial reservoirs allow the water to freeze back into ice before it flows further. Over time, layers of ice build up on top of each other, creating a water storage system.
In recent years, individual community leaders and NGOs have garnered much attention outside of Himalayan communities and around the world. This is how these projects caught the eyes of Chileans for the first time. The recent expansion of trans-Himalayan ice reservoir projects is a powerful example of community-led, locally designed water management solutions.
“Their priority was really about empowering communities to solve their own problems, and creating an education system to train people in the area to[do this],” Lyons said.
Markus Neisser, a professor at the University of Heidelberg, has studied the history, development, and efficacy of the practice in Himalayan communities. “These types of reservoir ice have a very long history in places like (region of) Ladakh, India,” he said in an interview with GlacierHub.
Nuesser notes that the particular type of ice reservoir on which the Chilean engineers are designing their project, the Ice stupa, is a relatively new iteration of an old practice. Ice towers work by spraying tiny water droplets to create and store snow. Designed and popularized by engineer Ladakhi Sonam Wangchuk around 2015, a surge of interest and funding followed. “They had something like a competition between different villages – which village builds the highest village,” Neisser recalls.
However, a significant barrier to ensuring the success of an ice stupa depends on an adequate maintenance workforce. In Ladakh, many of the early projects have been expanded by NGOs that have received international funding. Neisser notes that once projects were launched and funding dried up, communities often struggled to keep the ice towers operating. This was partly due to the dwindling agricultural labor force across this region, which had long been characterized by mass outward migration.
“These structures (need) a lot of maintenance,” said Neisser. “When they run out of money, I’ve seen many cases where they let[them]down. … When the hype is over, the structure has some problems.” When he visited Ladakh last winter, Nesser said, he saw several impressive buildings in poor condition.
The need for a suitable workforce is also a major challenge in Chile, where very few people live in the mountainous regions around which the melted glacial water can be captured. Without eyes to look for burst pipes, slow flow rates, or other issues, the project could be compromised. However, Nilus engineers are testing remote sensing and artificial intelligence technologies to control how and where ice forms on top of the structure.
The Chilean context adds another unique barrier: the privatized water rights structure that determines how water is used downstream. Water privatization was first signed into law by the dictatorship of Augusto Pinochet in 1980, creating a formal market for buying, selling and leasing water rights within the country. Last year, Chileans rejected a new constitution that would have largely abolished the provision.
The law draws a fine line between privatizing glaciers and privatizing their waterways. “You can’t privatize the water from a glacier in the sense that you can’t just put a hose in there and say, ‘It’s all mine,’” Lyons explained. “But with the water melting, as it does every season, and in abundance now because of climate change, it belongs to someone. This has a complication: Where will the water go? And for whom? “
Nesser agrees. “It’s a completely different set of problems,” he said, noting that the expansion of the Chilean mining sector adds another layer of problems, given that mining operations typically require large amounts of water, and may raise interest in the water supply of the new icy stupa. Nesser, however, remains cautiously optimistic. “This can work if they keep people informed about ownership in this,” he said.
For Lyons, the water rights case in Chile highlights the limitations of what a startup can do to address regional water scarcity. It noted the persistence of water stress exacerbated by internal migration from the northern and central parts of Chile to the southern provinces. But they are also still stuck in a model economically themselves. In such a privatized system, how much flexibility do you have for the project to actually become (a climate solution)? “
Nuesser also notes that even if the project manages to hold on to glacier meltwater well into the agricultural season, it won’t mitigate glacier loss as a whole.
“They (ice tanks) are very successful concepts to fill this critical water scarcity gap. But in another way, there is no additional water entering the system,” he said. It helps meet the water demand for this year, and possibly for next year. But it won’t help in the long run, when the primary water sources run low.”
Lyons agreed. “It’s still very speculative, but for me, what I see is that in this moment of heightened awareness about climate change and global warming, it would be helpful if the ice towers did something to better conserve and distribute the meltwater.”
Efforts in Chile to scale up the pilot project near Santiago will show whether this much-lauded example of South-South technology transfer has proven effective.
GlacierHub is a climate communications initiative led by Ben Orloff, an anthropologist at the Columbia School of Climate. Many GlacierHub writers are students or alumni of the Climate School.