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Landslip likely triggered Flash Flood: experts
What is the News?
According to glaciologists and experts, the cause of flash floods in Uttarakhand Chamoli district was most probably a landslip(Landslide) and not a glacial lake burst.
Why are experts calling it a Landslide and not a glacial lake burst?
- The glacial lake outburst flood(GLOF) occurs when a natural lake, formed from a glacial ice melt and the glacial lake is breached. However, available satellite images do not show the presence of a glacial lake before the flooding event.
- Moreover, the Central Water Commission(CWC) monitors and prepares monthly reports on the state of glacial lakes and waterbodies measuring 10 hectares and above via satellite. Nothing out of the ordinary was observed by CWC.
Then, what might have caused the flooding?
- There was a hanging glacier and on top of the glacier was a huge rock mass.
- The rock mass became loosened due to freezing, thawing, and temperature variation. It came crashing down, creating pressure on the hanging part of the glacier. The fresh snowfall had also been added to the weight over the hanging glacier.
- This hanging glacier broke off due to gravitational pull, slid down with the entire rock mass. It slowed down near the base of the valley, where the Raunthi Gadhera stream flows.
- As the huge mass slowed a bit, then stopped, it blocked the water of the stream and the water quantum kept increasing. This damming up of the stream increased to such an extent that it breached the whole accumulated mass of water.
- Hence, this whole mass of water, boulders, and rock mass came crashing down with force towards the Rishi Ganga dam site. It caused massive damage to the under-construction Tapovan hydel project and caused floods.
Source: The Hindu
More Related post
Fragility of Himalayan Mountain Ecosystem
Gs3: Conservation, Environmental Pollution, and Degradation, Environmental Impact Assessment.
Synopsis: The recent Glacial outburst in Uttarakhand’s Chamoli district is a consequence of human’s impact on climate and lack of awareness towards local ecology.
- Recently a glacier collapsed in Uttarakhand’s Nanda Devi. According to some satellite images, the glacier collapsed as a result of a landslide. It resulted in flash floods in the Rishiganga and Dhauliganga rivers.
- It claimed many lives of persons working in two hydropower projects.
- Although the ITBP through immediate action rescued nearly 15 people still many people are found missing.
How Climate change is impacting the Mountain ecosystem and how it is impacting Human livelihood?
- Anthropogenic activities are continuously affecting the earth’s climate. The change in the Mountain ecosystem is an indicator of that effect.
- Mountain ecosystems are highly vulnerable to climate change owing to their altitude, slope, and orientation to the sun.
- Due to increased global warming, mountains glaciers are melting at unprecedented rates. It is reducing the area for the survival of flora and fauna.
- For example, satellite observations reveal that across India, China, Nepal, and Bhutan the melting of glaciers has doubled since the start of the 21st century.
- The melting of glaciers threatens water sustainability for hundreds of millions of people in counties, including India. These impacts become severe due to the increase in pressure on water resources for irrigation and food production, industrialization, and urbanization.
What are the reasons for climatic disaster in Uttarakhand?
The frequent disasters in Uttarakhand are not only caused by nature but also due to an indiscriminate increase in hydropower projects.
- Uttarakhand mountain ecosystem faces various threats such as seismicity, dam-induced micro seismicity, landslides. For example, the entire State of Uttarakhand falls under Zone-IV and V of the earthquake risk map of India.
- Besides being an earthquake-prone zone, it is also prone to Flood disasters. Bursting of glacial lakes can cause flash floods with catastrophic consequences. For instance, moderate earthquakes in the Tehri dam caused the 2013 floods in Kedarnath.
- Despite all these threats, the Uttarakhand government has indiscriminately pursued a greater number of hydropower projects. For example, the ongoing Tapovan power project.
- Also, India has heavily invested in dam development and the growth of hydropower in the Himalayas’ region to cut carbon emissions.
- For example, if the national plan to construct dams in 28 river valleys in the hills is completed, the Indian Himalayas will have one dam for every 32 km. (The highest density in the world).
- Apart from this, the life of dams is often exaggerated without taking a proper account of the siltation level in the dams. For example, in the Bhakra dam in Himachal Pradesh, the siltation was higher by 140% than calculated.
These hydropower projects are incompatible with the local environment and ecology. They have increased the risk of disaster manifolds impacting the life and livelihood of millions of people.
What is the way forward?
- The government should realize that the fragility of the Himalayan mountain’s ecosystems. Governments need to re-prioritize their projects based on the potential of the mountains, local and traditional knowledge as well as the aspirations of the place.
- Hydro projects should be confined to the areas with the least impact in the Himalayas. Also, the government needs to build more low-impact run-of-the-river power projects rather than building destructive large dams and reservoirs.
- Projects that are incompatible with the local environment and ecology should not be promoted just by giving due consideration to development or economic growth.
What are the “NDMA guidelines for GLOFs related disasters”
What is the News?
NDMA has issued guidelines to reduce disasters related to Glacial Lake Outburst Floods (GLOFs). Recently GLOF is suspected to have caused the flash floods in Uttarakhand’s Chamoli.
What are Glacial Lake Outburst Floods(GLOFs)?
- It refers to the flooding that occurs when the water dammed by a glacier or a moraine is released suddenly.
- According to National Disaster Management Authority (NDMA), Climate change is facilitating the glacial retreat in most parts of the Hindu Kush Himalayas. It is resulting in the formation of numerous new glacial lakes. Due to that, this area has become prone to GLOFs.
NDMA Guidelines for Reducing GLOFs:
The NDMA, headed by PM, had issued detailed guidelines on how to reduce and deal with disasters caused by GLOFs:
- Identify and Mapping Dangerous Lakes: Potentially dangerous lakes can be identified. This identification will be based on field observations, past events, geomorphologic and geotechnical characteristics, etc.
- Use of Technology: It has recommended the use of Synthetic-Aperture Radar imagery. It will automatically detect changes in water bodies, including new lake formations, during the monsoon months.
- Structural Measures: It recommends reducing the volume 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.
- Example: In 2014, a landslide occurred along Phuktal (tributary to Zanskar river) in Kargil district of Ladakh. It led to a potential flood situation. The NDMA created an Expert Task Force which along with the Army used explosives to channel water from the river. It used controlled blasting and manual excavation of debris for this purpose.
- Constructions and development in High prone areas should be prohibited. It is a very efficient means to reduce risks at no cost.
- Land Use Planning: Land use planning regulations need to be developed. In downstream areas, Infra. development should be monitored prior to, during, and after the construction.
- Trained Local Manpower: Apart from specialized forces such as NDRF, ITBP, and the Army, there is a need for trained local manpower. These teams will assist in planning and setting up emergency shelters, distributing relief packages, identifying missing people, and addressing the needs for food, healthcare, water supply, etc.
- Early Warning System: A robust early warning system in vulnerable zones should be put in place.
- Emergency medical response team: Quick Reaction Medical Teams, mobile field hospitals, Accident Relief Medical Vans, and heli-ambulances should be set up in areas inaccessible by roads.
- Psychological Counselling: The guidelines also call for psychological counseling of victims.
Source: Indian Express
Glacial Lake Outburst Flood (GLOF) in Uttarakhand -Explained
Recently a glacial burst has occurred in Nanda Devi glacier in Uttarakhand’s Chamoli district. 19 bodies have been recovered so far and over 150 persons went missing in the glacial outburst. Many geologists issued warnings that these types of climate-related disasters are going to increase. They all pointed out global warming as a major contributing factor to these disasters.
What happened in Uttarakhand?
A part of the Nanda Devi glacier broke off and flooded the Rishiganga river in Chamoli district of Uttarakhand. It led to massive flood in the region that damaged many villages in its path. The flood also wiped out two hydroelectric power projects on its way;
- The Rishiganga hydroelectric power project (13.2 MW)
- The Tapovan hydroelectric power project on the Dhauliganga river (a tributary of the Alakananda).
The scientists call the glacial burst an “extremely rare event”. Whether it was a glacial lake burst or an avalanche, is still unknown.
Wadia Institute of Himalayan Geology, Dehradun has sent two teams of scientists to the area. The team will study the possible cause and find out the exact reason behind the glacial burst.
What is a glacier? and what is glacier retreat?Glaciers are large masses of ice that flow slowly downhill like water flowing down as a river. A glacier grows (advance) whenever snow accumulates faster than it melts. Glacier retreats (shrinks) whenever the melting exceeds accumulation. Most of the world’s glaciers have been retreating since about 1850.
What is Glacial burst?
Retreating glaciers, usually result in the formation of lakes at their tips. These lakes are called proglacial lakes. These proglacial lakes are often bound by sediments, boulders, and moraines.
If the boundaries of these lakes are breached, then flooding will take place downstream of that glacial lake. This is called a Glacial Lake Outburst Flood or GLOF.
The occurrence of GLOF will release a significant amount of water retained in a glacial lake. A large amount of water rush down to nearby streams and rivers (like the recent glacial burst that flooded the Rishiganga river). This further gathers momentum by picking up sediments, rocks, and other materials on the way.
In conclusion, GLOF will result in large scale flooding downstream.
These GLOFs have three major characteristics. They are,
- There will be a sudden release of water and sometimes this might be cyclic in nature.
- GLOFs are generally rapid events. They can range from a few hours to days.
- GLOFs result in large downstream discharges in the river. (This often depend on the amount of glacial lake size, level of the breach in the boundary of the glacial lake, etc).
What are the possible reasons behind the Glacial burst?
Due to multiple reasons, there occurs breach of boundaries of the glacial lake. Like,
- A build-up of water pressure or structural weakness of the boundary due to an increase in the flow of water.
- An earthquake (Tectonic) or cryoseism (non-tectonic seismic event of the glacial cryosphere) can cause GLOF. During this, the boundary of the glacial lake will collapse suddenly and release the water of the glacial lake.
- An avalanche of rock or heavy snow: During this, the water in the glacial lake might be displaced by the avalanche.
- Volcanic eruptions under the ice can lead to GLOF. These volcanic eruptions might displace the boundary or increase the pressure on the glacial lake or both.
- Heavy rainfall/melting of snow: This can lead to massive displacement of water in a glacial lake.
- Long-term dam degradation can also cause GLOF.
- Other reasons include the collapse of an adjacent glacial lake, etc.
Some significant glacial burst that occurred in the past:
The Glacial Lake Outburst Flood occurs all over the world except Australia (Glaciers are not found in Australia). Peru and Nepal in the past faced deadly or highly destructive glacial floods.
Dig Tsho glacial lake was present in Eastern Nepal (in a valley next to Mount Everest). In 1985 a GLOF occurred in Dig Tsho and brought out the dangerous potential of glacial lakes nationally and internationally. The Dig Tsho GLOF resulted in an estimated loss of US$ 1.5 million but fortunately only 4-5 casualties.
So far 14 GLOF events have been recorded in Nepal. In another ten events, the outburst occurred in Tibet (China) but it affected Nepal.
A flood caused by a GLOF in 1941 in Peru led to the death of an estimated 1,800. This event has been described as a historic inspiration for getting into research regarding GLOF.
In India, in 1929, a GLOF occurred from the Chong Khumdan Glacier in the Karakoram. It resulted into flood in the Indus River.
Vulnerability of Hindu Kush-Himalayan Region to Glacial Lake Outburst Flood(GLOF):
The Hindu Kush Himalayan (HKH) region is known as Asia’s water tower. It has the maximum snow cover after the poles. The Hindu Kush Himalayan region sustains more than two billion people directly and indirectly.
First, there are numerous glaciers in the HKH region. For example, there are 8,800 glacial lakes in the Himalayas and these are spread across countries. Among these, more than 200 of these have been classified as dangerous. These glacial lakes can trigger the Glacial outburst.
Second, the soil is getting loose in the HKH region. The large human settlements and human activities have resulted in deforestation and large-scale agricultural activities in the region. This intensifies the GLOF, as there is no natural barrier to control the flood.
Third, the factor of global warming and climate change. These are one of the most important reasons for the Glacial Lake Outburst Flood. Global warming and climate change lead to glacial retreat and glacier fragmentation (big glaciers splitting into smaller ones).
According to the Hindu Kush Himalaya Assessment report, even after fulfilling the commitments made under the Paris Agreement, one-third of the HKH region’s glaciers would melt and will potentially destabilize the river regime in Asia.
Fourth, the heat-island effect in the HKH region. The Himalayas are getting warm faster than other mountain ranges. This is due to the increase in the use of reinforced concrete (RCC) in building construction instead of eco -friendly traditional wood and stone masonry. This adds to regional warming and increases the number of glacial lakes or the water level of glacial lakes.
Fifth, tectonic activity in the region. The Indian plate is continuously moving towards north about 2 cm every year. So the Himalayas is rising about 5 mm a year. This makes the Himalayan region geologically active and structurally unstable. Landslides and earthquakes will continue to happen in the region. This can trigger a Glacial outburst.
For example, the entire State of Uttarakhand is categorized as Zone IV (High-Risk Zone) and V ( Very High-Risk zone) of the earthquake risk map of India.
First, a long-term solution will be feasible if all the countries start working towards reducing global warming.
Second, India needs to form clear policy guidelines to restrict further human activities like building roads, constructing hotels on banks, etc. Any further human activity without proper guidelines will harm the already fragile landscape.
Third, India needs to undertake a cumulative assessment and strategic planning. Geological Survey of India can use satellite images and technology like GIS (geographic information systems) and provide a clear analysis of the HKH region.
Fourth, Capacity building of the local community will ensure disaster mitigation in the near future.
Fifth, The government has to be proactive and set up an early warning system in the Himalayas. Like the one set up in coastal areas after the 2004 tsunami.
In conclusion, India is one of the most vulnerable countries to climate change and global warming. Even though international cooperation is required to restrict the global temperature to 1.5°C, India can move ahead and implement the suggestions. With this India can be a role model to the other countries in mitigating the disasters.
Importance of Ladakh’s Pangong Tso Lake
Pangong Tso Lake is an endorheic lake (landlocked) located in eastern Ladakh. It lies partly in India’s Ladakh region and partly in Tibet. The lake is formed from Tethys geosyncline.
- The lake literally translates into a “conclave lake”. Pangong means conclave in Ladakhi and Tso means a lake in the Tibetan language.
- The Karakoram Mountain range which crosses Tajikistan, Afghanistan, Pakistan, China and India ends at the north bank of Pangong Tso.
- The lake’s water is crystal clear, brackish making it undrinkable. The lake freezes during the winter allowing some vehicular movement on it as well.
- Who controls Pangong Tso?
Nearly two-thirds of the lake is controlled by China with just about 45 km under Indian control. The Line of Actual Control(LAC) running north-south cuts the western part of the lake, aligned east-west.
- Importance of the lake:
- The legendary 19th century Dogra general Zorawar Singh is said to have trained his soldiers and horses on the frozen Pangong lake before invading Tibet.
- The north of the lake, lies Army’s Dhan Singh Thapa post, named after Major Dhan Singh Thapa
- LAC(Line of Actual Control) mostly passes on the land, but Pangong Tso is a unique case where it passes through the water as well
- The importance of the lake is due to the fact that it lies in the path of the Chushul approach of China. (China uses Chushul valley for performing offensive activities into Indian-held territory).
- Over the years, the Chinese have built motorable roads along their banks of the Pangong Tso
- In 1999, when the Army unit moved to Kargil for Operation Vijay, China took the opportunity to build 5 km of the road inside Indian territory along the lake’s bank. This is used by China for tactical advantage.
- Endorheic (Landlocked) Lake: It is a collection of water within an endorheic basin or sink, with no evident outlet. The Endorheic lakes are generally saline (unable to get rid of solutes left during evaporation).
Hazardous ideas for Himalayas
Context: China’s major hydropower project as a part of its 14th Five-Year Plan (2021-25), on the Yarlung Zangbo River, in Mêdog County in Tibet.
More on news:
- The hydropower generation station is expected to provide 300 billion kWh of electricity annually. The Chinese authorities say the project will help the country realise its goal of reaching a carbon emission peak before 2030 and carbon neutrality before 2060.
- Indian counterparts were quick to restate their plans to dam the Himalayas on this side of the border. India is reportedly considering a 10-GW hydropower project in an eastern State.
What are the various misadventures that can happen due to the building of hydropower dams?
- Unavailability of dams: Both countries ignore how unviable such ‘super’ dams projects are, given that they are being planned in an area that is geologically unstable.
- Competing dams: Over the past 20 years, both China and India have been competing with each other to build hydroelectric dams in this ecologically fragile and seismically vulnerable area.
- There are two hydropower projects in the works in Arunachal Pradesh on the tributaries of the Brahmaputra: the 600 MW Kameng project on the Bichom and Tenga Rivers and the 2,000 MW Subansiri Lower Hydroelectricity Project.
- China has already completed 11 out of 55 projects that are planned for the Tibetan region.
- Overestimating economic potential: In executing these hydroelectric projects, the two countries have overestimated their economic potential and grossly underestimated the earthquake vulnerability of the region.
- Earthquakes in the region: High seismic zones coincide with areas of high population concentration in the Himalayan region where landslides and glacial lake outburst floods are common.
- About 15% of the great earthquakes of the 20th century occurred in the Himalayan region. The northeast Himalayan bend has experienced several large earthquakes of magnitude 7 and above in the last 100 years, more than the share from other parts of the Himalayas.
- The 2015 Gorkha earthquake of magnitude 7.8 in central Nepal resulted in huge losses in the hydropower sector. Nepal lost about 20% of its hydropower capacity consequent to the earthquake.
- Landslides: The main mechanisms that contributed to the vulnerability of hydropower projects were found to be landslides, which depend on the intensity of seismic ground shaking and slope gradients.
- Heavy siltation from giant landslides expected in the project sites will severely reduce the water-holding capacity and life expectancy of such dams.
- Even without earthquakes, the steep slopes made of soft rocks are bound to slide due to deforestation and road-building.
What can be done?
- Nature reserve: In recent years, the Himalayas have seen the highest rate of deforestation and land use changes. The upper Himalayas should be converted into a nature reserve by an international agreement.
- Himalayan river commission: The possibility of a Himalayan River Commission involving all the headwater and downstream countries needs to be explored.
- India and China, the major players in the region, would be well advised to disengage from military adventurism and seek ways of transforming this ‘roof of the world’ into a natural reserve for the sake of humanity. Carbon neutrality should not be at the expense of the environment.