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Glacial Lake Outburst Floods

GS Paper I – Geographical features and their location- changes in critical  geographical features (including water bodies and ice caps)

GS Paper 3 – Environmental Pollution and Degradation, Disaster and Disaster Management

Why in the news?

A list of 189 “high-risk” glacial lakes has been finalized by the National Disaster Management Authority (NDMA) in order to implement mitigation measures that will mitigate the risk that these lakes provide.

Overview :

To identify glaciers’ vulnerability to Glacial Lake Outburst Floods (GLOF), the National Disaster Management Authority (NDMA) has started sending expeditions to glaciers 4500 meters and higher.

The NDMA has identified 189 high-risk glacier lakes in the Indian Himalayas that need mitigation measures out of the over 7,500 glacial lakes total.

Glacial Lake Outburst Flood (GLOF) :

A glacial lake outburst floods (GLOF) is a kind of catastrophic flood that happens when a glacier lake’s dam breaks and a significant amount of water is released.

A sudden release of water that has been dammed by a glacier or a moraine is known as a GLOF.

As glaciers melt, the water in these glacial lakes builds up behind natural ‘glacial/moraine dams’ formed from ice, sand, pebbles, and ice residue.

The abrupt collapse of the moraine dam on top of the glacial lake, which contains a considerable amount of water, is caused by its weak structure, in contrast to earthen dams.

This kind of flood is usually brought on by the glaciers melting quickly, the accumulation of water in the lake as a result of intense precipitation, or the inflow of meltwater.

About the National Glacial Lake Outburst Floods Risk Mitigation Programme (NGRMP) :

  • The Government of India started this project to address the threats that GLOFs represent.
  • Fifteen of the sixteen teams that set out on the excursion returned with their findings. There are seven more expeditions under progress.
    Six expeditions were carried out in Sikkim, six in Ladakh, one in Himachal Pradesh, and two in Jammu and Kashmir out of the total of fifteen expeditions.
  • Teams on expeditions measure water quality and flow rates, collect relevant hydrological and geological samples and data, identify risk zones, notify populations downstream, and evaluate the structural stability and possible breach locations of glacier lakes.

 Objective of NGRMP :

The implementation of automated monitoring and early warning systems, hazard assessment, and lake-lowering techniques are necessary to reduce the risks associated with glacial lake outburst floods (GLOFs).

  • Lake-lowering techniques are ways to lessen the amount of water in a glacial lake to lessen the possibility of a glacial lake eruption.

The goal of NDMA is to ground-truth 189 glacial lakes that have been identified as “high-risk.”

  • The process of comparing data obtained from indirect methods, such as remote sensing, with direct observations conducted on the spot is known as “ground-truthing.”

Methodology for Preventing GLOF:

Three simultaneous actions are scheduled.

  • Installation of early warning systems, automated weather stations, and water level monitoring stations
  • Bathymetry and digital elevation modelling.
  • Determining the best ways to lessen the danger associated with that lake, including lake lowering.

Why are GLOFs under the spotlight?

  1. Rise in GLOF events in the Himalayas: According to the findings of the International Centre for Integrated Mountain Development (ICIMOD), The Hindu Kush Himalayas are changing quickly and irreversibly as a result of climate change, which raises the possibility of landslides and floods.
  2. Climate Change: Extremely changed FDI (frequency, duration, and intensity) of precipitation as well as excessive heat are threats that India faces as a result of climate change. It might cause more flash floods to occur.
  3. Previous GLOF Incidents:
    Incident in Nepal: Recently, Thyanbo glacial lake’s outburst flood caused flash floods to affect Thame, a village in Nepal’s Khumbu region.

Sikkim Flash Flood: In October 2023, a devastating flash flood took place in South Lhonak Lake, Sikkim.

The Chamoli district in Uttarakhand experienced flash floods in February 2021, which are thought to have been brought on by GLOFs.

Developments made by NGRMP:

  • The Tawang and Dibang Valley districts of Arunachal Pradesh are undergoing an assessment of high-risk glacial lakes conducted by the Arunachal Pradesh State Disaster Management Authority (APSDMA).
  • All of the nation’s glacial lakes are to be mapped as part of the broader National Glacial Lake Outburst Flood (GLOF) Mission of the NDMA.
  • Arunachal Pradesh’s High-Risk Glacial Lakes:
    Total Lakes at Risk: In Arunachal Pradesh, 27 high-risk glacial lakes have been found spread over five districts.
    Tawang (6 lakes), Kurung Kumey (1), Shi Yomi (1), Dibang Valley (16), and Anjaw (3) are the locations of the lakes.
    Three high-risk lakes in each of the districts of Tawang and Dibang Valley will be the focus of the current expedition teams’ attention.
  • Study Objectives: The group will look into the lakes in danger of GLOF’s accessibility, location, size, elevation, and land use in the surrounding area.
    This would facilitate the installation of an Automatic Weather Station and an Automatic Early Warning System by the Indian Meteorological Department and the Centre for Development of Advanced Computing (C-DAC).

Importance of the Research:

Strategic Location: China borders the districts of Tawang and Dibang Valley. The strategic location of it makes it a target for close observation.

Himalayan Ecosystem in Danger: India may experience landslides on the Chinese side of the border as a result of China’s interference with the region’s rivers and geology.

Danger of Floods: In 2018, China reported a landslide barrier at the Yarlung Zangbo River, prompting the governments of Arunachal Pradesh and Assam to issue flood warnings.

Heavy Infrastructure: There has been ongoing concern about the potential negative effects of China’s massive dam being built on the Yarlung Tsangpo River in Medog, close to the international border, extending from Arunachal to Assam.

PYQs:

  1. Consider the following statements about Glacial Lake Outburst Floods:
  2. It is a type of flood that occurs when a glacial lake experiences a sudden and rapid release of water.
  3. Building a barrier or dam across a glacial lake will eliminate the risk of GLOFs.

3.GLOFs are limited to high-altitude regions and do not pose a threat to lowland areas.

 How many of the above statements is/are correct?

  1. Only One b) Only Two c) All Three d) None

Q2. Consider the following pairs (2019)

Glacier River

  1. Bandarpunch: Yamuna
  2. Bara Shigri: Chenab
  3. Milam: Mandakini
  4. Siachen: Nubra
  5. Zemu: Manas

Which of the pairs given above are correctly matched?

  • 1, 2 and 4 (b) 1, 3 and 4 (c) 2 and 5 (d) 3 and 5

Q3. Siachen Glacier is situated to the (2020)

(a) East of Aksai Chin

(b) East of Leh

(c) North of Gilgit

(d) North of Nubra Valley

Mains Q. With reference to National Disaster Management Authority (NDMA) guidelines, discuss the measures to be adopted to mitigate the impact of the recent incidents of cloudburst in many places of Uttarakhand. (2016)

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