Uttarakhand to study risk posed by 13 glacial lakes during monsoon

Sub: Geography

Sec: Climatology

Vulnerability Study of Glacial Lakes in Uttarakhand:

The Uttarakhand State Disaster Management Department (USDMA) is initiating a vulnerability study of 13 glacial lakes, with five identified as being in high-risk zones.
Purpose: The study aims to provide essential data to prevent calamities such as lake outbursts, particularly during the monsoon season.

Identification and Characteristics of High-Risk Glacial Lakes:

Location: The high-risk lakes are located in Darma, Lasaryanghati, and Kutiyangti valleys in the Pithoragarh district, and Vasudhara Tal Lake in Chamoli district.
These lakes range from 0.02 to 0.50 sq. km and are situated above 4,000 meters above sea level.

Bathymetry Study and Risk Assessment

Approach: USDMA teams will conduct a bathymetry study to gather accurate information on lake size, glacier formation, and melting patterns.
Collaboration: The Indo-Tibetan Border Police has been involved in providing a status report on the high-risk lakes.

Risk Mitigation Strategies:

USDMA plans to puncture the high-risk lakes and install pipes to manage potential risks.

Historical Context and Recent Incidents

Uttarakhand has experienced two significant glacial lake outburst floods (GLOFs) in recent years.
The 2013 Kedarnath Valley GLOF resulted in 6,000 deaths, while the 2021 Rishighanga Valley GLOF claimed 72 lives, highlighting the urgency of preventive measures.

Glacial lake outburst floods (GLOFs):

A glacial lake outburst flood (GLOF) is a release of meltwater from a moraine– or ice-dam glacial lake due to dam failure.
GLOFs often result in catastrophic flooding downstream, with major geomorphic and socioeconomic impacts.
GLOFs have three main features:
- They involve sudden (and sometimes cyclic) releases of water.
- They tend to be rapid events, lasting hours to days.
- They result in large downstream river discharges (which often increase by an order of magnitude).

The following direct causes of glacial lake outburst floods were documented:
- Rapid slope movement into the lake
- Heavy rainfall/snowmelt
- Cascading processes (flood from a lake situated upstream)
- Earthquake
- Melting of ice incorporated in dam/forming the dam (including volcanic activity-triggered jökulhlaups)
- Blocking of subsurface outflow tunnels (applies only to lakes without surface outflow or lakes with a combination of surface and subsurface outflow)
- Long-term dam degradation

Source: TH