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07 May

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Satellite Observations Show Rapid Expansion Of Glacial Lakes In Indian Himalayas

Introduction

The Indian Himalayan Region (IHR) is witnessing a rapid expansion of glacial lakes due to accelerated glacier retreat driven by climate change. According to satellite-based observations released by ISRO, hundreds of glacial lakes across the Himalayas have expanded significantly between 1984 and 2023.The Himalayas, often called the “Third Pole”, contain vast reserves of snow and glaciers and act as a major freshwater source for rivers such as the:

  • Indus
  • Ganga
  • Brahmaputra

However, increasing glacial melting is creating new risks in the form of:

  • Expanding glacial lakes
  • Glacial Lake Outburst Floods (GLOFs)
  • Flash floods
  • Downstream ecological and infrastructure damage

Why Himalayas Are Called the “Third Pole”

The Himalayas are referred to as the Third Pole because:

  • They contain one of the largest freshwater reserves outside the Arctic and Antarctic regions.
  • Extensive glaciers and snowfields regulate South Asia’s hydrology.

The Himalayan cryosphere plays a critical role in:

  • River flow regulation
  • Agriculture
  • Drinking water supply
  • Hydropower generation
  • Ecosystem stability

Key Findings of the ISRO Study

ParameterFindings
Study Period1984–2023
Glacial lakes identified (>10 ha)2,431
Lakes significantly expanded676
Lakes located within India130
Major basin distributionIndus, Ganga, Brahmaputra

Basin-Wise Distribution of Expanding Lakes

River BasinNumber of Lakes
Indus Basin65
Ganga Basin7
Brahmaputra Basin58

The highest concentration of expanding lakes was observed in the Indus and Brahmaputra basins.


Magnitude of Expansion

Expansion Pattern

Expansion LevelNumber of Lakes
Expanded more than twice601
Expanded 1.5–2 times10
Expanded around 1.5 times65

The data indicates rapid glacier retreat and accelerated meltwater accumulation.


Elevation-Wise Distribution

Elevation RangeNumber of Lakes
4,000–5,000 metres314
Above 5,000 metres296

Most expanding lakes are located at very high altitudes where field monitoring is difficult.


Types of Glacial Lakes

8Glacial lakes are classified based on their formation process.

TypeCharacteristics
Moraine-Dammed LakesWater blocked by loose moraine debris
Ice-Dammed LakesWater blocked by ice barriers
Erosion LakesFormed in depressions created by glacial erosion
Other Glacial LakesMiscellaneous formation mechanisms

Dominant Category

Among the 676 expanding lakes:

TypeNumber
Moraine-Dammed307
Erosion Lakes265
Other Lakes96
Ice-Dammed8

Moraine-dammed lakes are particularly dangerous because their natural dams are weak and unstable.


Case Study: Ghepang Ghat Glacial Lake

Location

  • Himachal Pradesh
  • Indus River Basin
  • Elevation: 4,068 metres

Key Findings

ParameterData
Area in 198936.49 hectares
Area in 2022101.30 hectares
Increase178%
Annual Expansion Rate1.96 hectares/year

The Ghepang Ghat lake exemplifies rapid Himalayan glacial transformation.


What is GLOF?

Glacial Lake Outburst Flood

A GLOF occurs when a glacial lake suddenly releases large quantities of water due to failure of its natural dam.

Causes of GLOFs

  • Moraine dam collapse
  • Ice avalanches
  • Rockslides
  • Earthquakes
  • Extreme rainfall events
  • Rapid glacier melt

Risks Associated With Expanding Glacial Lakes

Human and Infrastructure Risks

Potential impacts include:

  • Flash floods
  • Destruction of roads and bridges
  • Hydropower damage
  • Loss of lives and livelihoods

Ecological Risks

  • River channel instability
  • Sedimentation
  • Wetland destruction
  • Biodiversity loss

Climate Change and Glacier Retreat

The study reinforces evidence that:

  • Global warming is accelerating glacier melting.
  • Himalayan glaciers are retreating rapidly.

Major contributing factors include:

  • Rising temperatures
  • Reduced snowfall
  • Extreme weather events
  • Heatwaves

Role of Satellite Remote Sensing

Importance

Satellite remote sensing is critical because Himalayan terrain is:

  • Rugged
  • Inaccessible
  • Hazard-prone

Advantages

  • Wide-area coverage
  • Repeated observations
  • Long-term monitoring capability
  • Change detection over decades

The study used satellite archives spanning nearly four decades.


Importance of Long-Term Monitoring

Long-term monitoring helps in:

  • Understanding glacier retreat
  • Mapping vulnerable lakes
  • GLOF risk assessment
  • Climate adaptation planning

It also assists governments in:

  • Disaster preparedness
  • Early warning system development
  • Infrastructure planning

Need for Disaster Risk Reduction

The growing number of expanding lakes highlights the need for:

  • Early warning systems
  • Automated weather stations
  • Community preparedness
  • High-altitude monitoring networks

India has increasingly focused on glacial lake risk management after major Himalayan disasters.


Relevance for India

Water Security

Glacial melt directly influences:

  • River discharge
  • Irrigation systems
  • Drinking water availability

Strategic Importance

The Himalayan region is ecologically and geopolitically sensitive because it includes:

  • Border regions
  • Hydropower corridors
  • Fragile mountain ecosystems

STATIC PART

ISRO

FeatureDetails
Full FormIndian Space Research Organisation
Established1969
HeadquartersBengaluru
FunctionSpace research, satellite applications and remote sensing

Indian Himalayan Region (IHR)

FeatureDetails
ImportanceSource region of major Himalayan rivers
Ecological RoleMajor cryosphere and freshwater reserve

GLOF

FeatureDetails
Full FormGlacial Lake Outburst Flood
NatureSudden release of glacial lake water

Sentinel Satellite Data

FeatureDetails
FunctionEarth observation and environmental monitoring

Updated – 22 April 2024 | ISRONews Source: ISRO

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