Nepal’s glaciers are the source of the rivers that sustain hundreds of millions of people across Nepal, India, and Bangladesh. They are also melting faster than at any point in recorded history. Understanding Nepal’s glaciers means understanding both an extraordinary natural system and one of the greatest climate challenges of our time.
The Water Tower of Asia
The Himalayas are often called the “Water Tower of Asia” because they store more freshwater as snow and ice than anywhere on Earth outside the polar regions. These glaciers feed ten of Asia’s major river systems — including the Ganges, Brahmaputra, and Indus — which together supply water to roughly 1.9 billion people.
Nepal sits at the heart of this system. Its glaciers and snowfields feed the Koshi, Gandaki, and Karnali — the three great river systems that drain the country.
How Many Glaciers Does Nepal Have?
Nepal has 1,466 glaciers covering approximately 3,902 km² — about 2.6% of Nepal’s total area. Recent inventories using satellite imagery suggest the number may be closer to 2,315 glacial lakes covering 75 km² across Nepal.
| Statistic | Number |
|---|---|
| Glaciers | ~1,466 |
| Glacier area | ~3,902 km² |
| Glacier ice reserves | ~312 km³ |
| Glacial lakes | ~2,315 |
| Glacial lake area | ~75 km² |
Most of Nepal’s glaciers are concentrated in three regions:
- Eastern Nepal (Everest, Kanchenjunga region)
- Central Nepal (Langtang, Manaslu, Annapurna, Dhaulagiri)
- Western Nepal (Karnali basin, Dolpo, Humla)
The Major Glacial Lakes
1. Tsho Rolpa (Rolwaling)
Tsho Rolpa is one of Nepal’s most studied glacial lakes. It sits at 4,580 meters in the Rolwaling Valley (Dolakha district) and has grown dramatically over the past century — from a small pond in the 1950s to a lake over 1.5 km long today.
Because of the risk of a glacial lake outburst flood (GLOF), Tsho Rolpa has been the focus of a major engineering intervention — a canal was built in 2000 to lower the lake level by 3 meters, reducing the danger to downstream communities.
2. Imja Tsho (Everest Region)
Imja Tsho, at 5,010 meters in the Khumbu region, is one of the fastest-growing glacial lakes in Nepal. It has expanded from almost nothing in the 1960s to over 1 km² today. The lake is fed by the Imja Glacier, which has retreated rapidly over the past 60 years.
Concerns about a GLOF have prompted ongoing monitoring. Downstream settlements in the Khumbu, including parts of the Everest Base Camp trekking route, could be affected if the moraine dam fails.
3. Thulagi Lake (Western Nepal)
Thulagi sits at 4,250 meters in the Manang district, in the Marsyangdi River basin — the same river system that feeds the Annapurna Circuit trek. It is considered one of the highest-risk glacial lakes in Nepal.
4. Lower Barun Lake (Eastern Nepal)
Lower Barun, at 4,570 meters in Sankhuwasabha district, has grown significantly in recent decades. Downstream risks affect communities along the Barun and Arun rivers.
The GLOF Problem
A Glacial Lake Outburst Flood (GLOF) occurs when the dam of loose moraine material holding back a glacial lake collapses — either from melting ice, an avalanche into the lake, an earthquake, or simply overflow after heavy rain.
The resulting flood is catastrophic. A wall of water, mud, and debris rushes downstream, destroying everything in its path.
The 1985 Dig Tsho Disaster
The most famous GLOF in Nepal was the Dig Tsho outburst of August 4, 1985 in the Khumbu region. A moraine dam collapsed, releasing 6–10 million cubic meters of water. The flood swept down the Bhote Koshi valley, destroying:
- 14 bridges
- The Namche hydroelectric plant
- Dozens of homes and livestock
- Trekking trails
Miraculously, no one was killed — but the event shocked Nepal into taking glacier risk seriously. It led to the founding of monitoring programs and engineering interventions like the one at Tsho Rolpa.
GLOF Risk Today
Today, Nepali and international researchers monitor dozens of “potentially dangerous” glacial lakes. The most at-risk include:
- Tsho Rolpa (Dolakha)
- Imja Tsho (Solukhumbu)
- Thulagi (Manang)
- Lower Barun (Sankhuwasabha)
- Hongu (Solukhumbu)
Early warning systems have been installed in several high-risk valleys, giving downstream communities time to evacuate.
Glacier Retreat: The Modern Crisis
Nepal’s glaciers are retreating at alarming rates. Studies show:
- Everest region glaciers are retreating 10–59 meters per year, with some accelerating to 74 meters per year
- The Rikha Samba Glacier (Mustang) has been monitored since the 1970s and shows continuous mass loss
- Small glaciers below 5,000 meters are expected to disappear almost entirely within decades
The consequences are significant:
- Water scarcity in the dry season as glacial reserves shrink
- Increased GLOF risk as melting creates more and larger lakes
- Disruption to agriculture downstream as river flow becomes less predictable
Why This Matters Beyond Nepal
Nepal’s glaciers are not just a national concern. The Ganges, Brahmaputra, and Indus rivers that receive their meltwater support:
- 500+ million people directly dependent on glacial-fed rivers for drinking water
- Vast agricultural systems in India and Bangladesh
- Some of the world’s most densely populated regions
What happens to Nepal’s glaciers affects the food and water security of a large portion of Asia.
Frequently Asked Questions
Q: How many glaciers are in Nepal? Nepal has roughly 1,466 glaciers covering about 3,902 km², with around 2,315 glacial lakes.
Q: What is a GLOF? A Glacial Lake Outburst Flood (GLOF) happens when the moraine dam holding a glacial lake collapses, releasing a catastrophic flood downstream.
Q: What was the worst GLOF in Nepal? The 1985 Dig Tsho outburst in the Khumbu region destroyed 14 bridges and a hydroelectric plant. It’s the event that triggered major GLOF monitoring efforts in Nepal.
Q: Are Nepal’s glaciers melting? Yes — rapidly. Many glaciers are retreating 10–59 meters per year, with some accelerating further.
Q: What is the largest glacial lake in Nepal? Tsho Rolpa in the Rolwaling Valley is one of the largest and most studied. Imja Tsho in the Everest region is the fastest-growing.