The desert-like climate 3,500m up in Ladakh, India, is extreme: the winters are long and bitterly cold, and in summer, water is scarce. Farmers rely on glacial meltwater during the April and May planting season. But, with the retreat of the glaciers due to climate change, there’s less of that when they need it.
Teacher and mechanical engineer Sonam Wangchuk has come up with an ingenious solution. He’s found a way of piping water from winter snow-melt streams that no one can make use of, letting it freeze in the cold air and storing it as an ‘ice stupa’ – named after the mound-like Buddhist monuments of Ladakh and Tibet – until it melts in spring.
How can water flow high in the mountains, but freeze at lower levels?
It’s to do with surface area. A flat ice field at altitude melts faster in the sun than a vertical cone of ice in the valley. Wangchuk builds the stupa by spraying the water from a spike at the end of the pipe – it freezes in the cold air as it falls.
In 2015, the first stupa brought 1.5 million litres of water to 5,000 saplings planted near Phyang, 14km from Leh.