GLACIAL
LAKE OUTBURSTS – ENVIRONMENT
News: At least seven dead as glacial lake
bursts in Sikkim
What's
in the news?
●
At least seven people have died and scores
more were injured or missing after flash floods inundated Sikkim.
Key
takeaways:
●
The floods are believed to have been
triggered after a lake, forming from the gradual melting of a Himalayan
glacier, suddenly overflowed and inundated the Teesta river basin.
Glacial
Lake Outburst:
● Glacial
lakes result from shrinking glaciers.
Once the water is released from them, it could cause flooding in the downstream
areas. This is known as Glacial Lake Outburst Floods or GLOF.
●
The GLOFs have been taking place since the
ice age, the risk has increased multi fold due
to climate change.
Three
main features:
Causes:
1.
Structural weakness:
●
A buildup of water pressure or structural
weakness of boundary due to an increase in the flow of water.
2.
Earthquake:
●
An earthquake (Tectonic) or cryoseism
(non-tectonic seismic event of the glacial cryosphere) can also cause GLOF.
●
During this, the boundary of the glacial
lake will collapse suddenly and release the water in the glacial lake.
3. Volcanic eruptions:
●
Volcanic eruptions under the ice can also
cause GLOF. These volcanic eruptions might displace the boundary or increase
the pressure on glacial lakes or both.
4.
Heavy rainfall/melting of snow:
●
This can lead to massive displacement of
water in a glacial lake.
5.
Impact of Climate Change:
●
Climate change has driven erratic weather
patterns like increased snowfall and rainfall, warmer winters have led to the
melting of a lot of snow.
Impacts:
●
GLOFs can prove to be catastrophic as they
mostly arrive with little warning and result in large-scale destruction of
property, infrastructure and agricultural land. They can also lead to the death
of hundreds of people.
Mitigation
measures:
NDMA
guidelines:
1.
Identify and Mapping Dangerous Lakes:
●
Potentially dangerous lakes are often
identified.
●
This identification are going to be
supported by field observations, past events, geomorphologic and geotechnical
characteristics, etc.
2.
Use of Technology:
●
It is recommended to utilize the Synthetic-Aperture Radar imagery.
●
It will automatically detect changes in
water bodies, including new lake formations, during the monsoon months.
3.
Structural Measures:
●
It recommends reducing the number of water
with various methods to manage lakes structurally.
●
Methods are pumping or siphoning out water
and making a tunnel through the moraine barrier or under an ice dam.
●
Constructions
and development in High prone areas should be prohibited.
It's a very efficient means to reduce risks at no cost.
4.
Land Use Planning:
●
Land use planning regulations need to be
developed.
●
In downstream areas, Infrastructure
development should be monitored before, during, and after the construction.
5.
Empowered Local Manpower:
●
Apart from specialized forces like NDRF,
ITBP and the military, there is a requirement for trained local manpower.
●
They can assist in planning and fixing
emergency shelters, distributing relief packages, identifying missing people
and addressing the requirement for food, healthcare, water, sanitation, etc.
6.
Early Warning System:
●
A robust early warning system in
vulnerable zones should be put in place.
7.
Emergency response team:
●
Quick Reaction Medical Teams, mobile field
hospitals, Accident Relief Medical Vans and Heli-ambulances should be found in
areas inaccessible by roads.
WAY
FORWARD:
1.
Identification of potentially hazardous lakes:
●
By using field observations, historical
event records, the geotechnical and geomorphologic characteristics of the lake
or dam, and the surroundings, it is possible to identify potentially dangerous
lakes and determine additional physical problems.
2.
Improvement of early warning systems:
●
Even on a global scale, there are very few
GLOF early warning systems that have been implemented and are in operation.
●
Three instances of the use of sensor and monitoring based
technical systems for GLOF early warning in the Himalayan region have been
documented (two in Nepal and one in China).
3.
Uniform codes for construction activity:
●
Establishing a comprehensive framework for
excavation, construction and infrastructure development in vulnerable areas.
●
In areas where GLOFs are likely to occur,
land use planning procedures must be accepted.
4.
Training local people:
●
Since residents are often the first to
respond to a disaster before trained rescue personnel, it is important to train
them in search and rescue procedures.