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Ladakh's farmers need water at sowing time in April and May, but in winter the water from glaciers drains into streams without much use, according to a 2022 Leh Nutrition Project (LNP) report, Artificial Glaciers: Past, Present and Future. Chewang Norphel's answer was to store that winter water as ice.
Who is Chewang Norphel?
In 1987, a team led by engineer Chewang Norphel of the Rural Development Department in Leh developed the idea of artificial glaciers and experimented with it at Shara and Mudh villages, according to the LNP report. He took the idea to more villages in the 1990s after joining LNP, and came to be known as the ice man of India.
The Government of India named him in its Padma Awards 2015 list, released by the Press Information Bureau on 25 January 2015. With Padma Tashi, he described the method in a Springer book chapter, Snow Water Harvesting in the Cold Desert in Ladakh: An Introduction to Artificial Glacier.
How does an artificial glacier work?
The LNP report describes the cascade design in four moves:
Divert: from November, stream water is led off through channels or pipes at sites below the natural glacier.
Slow: a series of low walls of dry stone masonry checks the flow, so the water spreads out and sits still.
Shade: the sites are preferably shady, so the water freezes and the ice builds up through winter.
Release: because the ice sits lower than the natural glacier, it melts earlier, in April and May, just when fields need water.
The report adds that the structures help recharge groundwater and springs.
Why does the ice melt slowly? Latent heat
Latent heat is the energy a substance absorbs or releases while it changes state, without its temperature changing. For ice, that energy is large: the US National Bureau of Standards measured the heat of fusion of ice as 333.5 joules per gram (Osborne, 1939).
Compare that with warming liquid water, which takes 4,184 joules per kilogram per degree Celsius, according to the USGS. Divide 333.5 by 4.184 and you get about 80: the energy that melts one gram of ice would warm one gram of water by roughly 80 °C.
So a sheet of ice is an energy bank. Sunlight and warm air must pay in all those joules before any ice turns to water. Shade cuts one of the strongest supplies, direct sunlight, so the melt is slower. For the history, read about Joseph Black and the heat that thermometers cannot see; for practice, see reading latent heat from temperature-time graphs.
Worked example: how much energy is stored in one ice reservoir?
A 2019 study by Marcus Nüsser and colleagues estimated that one structure they measured stored between 1,010 and 3,220 cubic metres of water. Take the lower figure:
Mass: one cubic metre of water is about 1,000 kg, so 1,010 cubic metres is about 1.01 × 10⁹ grams.
Energy to melt: 1.01 × 10⁹ g × 333.5 J/g ≈ 3.4 × 10¹¹ joules.
In everyday units: one kilowatt-hour is 3.6 × 10⁶ joules, so that is about 94,000 kWh.
Upper figure: 3,220 cubic metres gives about 1.07 × 10¹² joules, close to 300,000 kWh.
All of that energy must arrive from the Sun, the air and the ground before the reservoir empties, so the ice gives its water back gradually. Try it yourself: a reservoir holding 500 cubic metres of meltwater. (Answer: about 1.7 × 10¹¹ joules, or roughly 46,000 kWh.)
If latent-heat numericals keep going wrong at the units step, the Fermi Problem Library has worked problems with a step-by-step solver that explains the reasoning rather than printing an answer.
Do artificial glaciers really work?
The Nüsser study examined 14 ice reservoirs using satellite data from 1969 to 2017 and repeat field measurements in 2014 and 2015. It estimated that the stored water could irrigate cropped areas between less than 0.1 times in unfavourable cases and almost 3 times in optimal cases and years. Local smallholders described real benefits: less seasonal water scarcity, lower risk of crop failure and the chance to grow cash crops.
The authors judged the structures remarkably suited to Ladakh's physical environment, but questioned their usefulness as a climate-change adaptation, because climatic variability, natural hazards and incomplete integration into the local socioeconomic setting reduce how well they work. The LNP report adds that many structures built in the 1980s and 1990s were washed away in the 2010 and later flash floods.
What can you learn from Norphel's idea?
Norphel used physics every Class 11 student meets, applied to a real calendar. When you study any design, ask three questions:
Where does the energy go, and how fast? Here, shade and stillness control the flow of heat.
When is the resource needed? Here, sowing time in April and May, not the summer melt.
What makes it fail? Here, variable winters and flash floods.
The Fermi Simulation Lab has interactive simulations for the ideas that are easier to see than to read. Then work through the related problem of how long ice takes to form on a pond.
