On August 18, 2024, an unusual flooding event swept through Thame village in the Everest region of Nepal. This incident was later identified by the Government of Nepal as a Glacial Lake Outburst Flood (GLOF). The Thame River, swollen with mud, gravel, and boulders, destroyed 20 houses, an elementary school, and a clinic in ward 5 of Khumbu Pasang Lhamu Rural Municipality. The flood displaced 135 people, leaving the riverside settlement carpeted with debris. The village of Thame, a prominent settlement in the Namche region of Solukhumbu district, now stands as a stark reminder of the looming threat posed by GLOFs.
In another alarming event, an avalanche in Mustang's Kobang area was observed and assessed by the federal government, which concluded that the incident was likely a GLOF. The continuous rain and rising temperatures in the region contributed to this catastrophic event. Such incidents highlight the urgent need for risk assessments and proactive measures to mitigate the dangers posed by glacial lakes, many of which are on the verge of bursting due to climate change.
GLOF Context in Nepal
Nepal is one of the most climate-vulnerable and disaster-prone countries globally. Its diverse geo-climatic system makes it highly susceptible to natural hazards, including earthquakes, floods, landslides, heatwaves, cold waves, and droughts. With global warming in Nepal projected to be higher than the global average, the country is already experiencing the effects of climate change. The frequency of extreme precipitation events is increasing, glaciers are retreating rapidly, snowfall days are decreasing, and permafrost is melting. These multi-hazard events cause significant damage, equating to an average of 2% of Nepal's GDP each year—a figure that can rise to 5% during extreme monsoon flooding or catastrophic events like the 2015 earthquake.
GLOF has become a critical topic of discussion among development professionals, academia, researchers, and government stakeholders in Nepal. GLOF occurs when meltwater from glaciers accumulates behind an ice or moraine barrier, which can then overtop or fail due to hydrostatic pressure, often triggered by an avalanche or landslide into the lake. The sudden release of large volumes of water results in devastating floods that can breach river channels, endangering nearby population centers and infrastructure, such as bridges. Due to the often-inaccessible terrain, most risk mapping is done using satellite imagery to monitor glacial lakes and their changes over time. In total, 49 glacial lakes in Nepal have been identified as larger than 0.02 square kilometers, and risk assessments have narrowed this number down based on factors like the lake's size, expansion, water levels, dam condition, and surrounding physical conditions.
GLOF is a significant source of flash and seasonal flooding in Nepal, primarily driven by the serious impacts of climate change, such as the melting of Himalayan ice. These floods are more extensive and destructive than other types of flooding, necessitating a more robust and coordinated response.
It was landslide dam outburst flood: ICIMOD expert
GLOF Disaster Management and Challenges
According to Nepal's Disaster Risk Reduction (DRR) Act of 2017, GLOF disaster management is a shared responsibility between federal, provincial, and local governments. However, there is a lack of clear delineation of roles and responsibilities for risk reduction, preparedness, relief, and response. While development partners are assisting the Government of Nepal (GoN) in responding to small and medium-scale emergencies like floods and landslides, these initiatives are not sufficiently scaled up to influence national policies for effective disaster preparedness and response.
There is also limited science-based research and tools for disaster risk management, particularly concerning GLOFs. Progress in strengthening preparedness and response capacities at the local level has been slow, and coordination between federal, provincial, and local governments is lacking. The choice of emergency preparedness and response actions remains inconsistent, further complicating efforts to mitigate GLOF risks.
Impact of GLOFs
The impact of GLOFs on Nepal's socio-economic landscape is profound. With no operational GLOF early warning systems in place, the country is ill-prepared to handle such disasters. Although there is a general hydro-meteorological early warning system, its reliability and accuracy need significant improvement. Furthermore, the lack of research, study, and assessment in the sector limits the effectiveness of current preparedness and response mechanisms.
GLOF anticipatory action is an emerging approach that aims to take early action ahead of predicted multiple hazards to reduce the impacts of shocks on vulnerable communities and their livelihoods. This innovative approach requires pre-agreed plans, reliable forecasts, early warning information, and pre-agreed financing that can be released swiftly when agreed triggers and thresholds are reached. However, implementing GLOF anticipatory action in Nepal requires a robust understanding of the socio-economic vulnerability profiles of communities and the development of science-based technologies and tools.
Despite these challenges, the urgency of addressing GLOF risks is clear. Each year, more than 600 people die, and millions of dollars in livelihoods and properties are lost due to various natural disasters, including GLOFs. The recent incidents in Thame and Mustang underscore the need for immediate action.
Climate Change and GLOF Risks
The risk of GLOFs is intricately linked to climate change. The dimension of the monsoon in Nepal has changed, with rainfall now extending into mountainous areas previously considered arid. Regions like Manang, Mustang, and Solu Khumbu, once known as Nepal's deserts due to low rainfall, are now facing increased flood risks. The combination of melting snow, weak rock formations, and lack of vegetation has made these areas particularly vulnerable to erosion and flooding.
Increased snowfall in the upper regions, which once acted as a cement to stabilize mud and stones, is no longer sufficient to prevent soil erosion. As snow melts, it carries debris with it, causing damage far beyond that of typical floods. This change in flood dynamics is evident in recent events in Taplejung, Sankhuwasabha, Bhemathang (Melamchi), and Kagkhola, where mountainous areas are now at risk of flooding. In Mustang, for example, the Kaligandaki River's level has increased by 9 inches annually, bringing the river dangerously close to settlements.
Given the growing risks, it is crucial to take measures to remove stones and sand from rivers and reduce the risk of flooding based on the local context. However, there is a significant gap in research and data on temperature changes in the mountainous regions. Without scientific evidence, it is challenging to predict and mitigate the risks associated with sediment accumulation above the ice line, commonly referred to as a "sediment bomb."
What Next: Addressing GLOF Risks
The threat posed by GLOFs requires immediate and sustained action. Reducing the risk of glacial lakes involves tracking these bodies of water with advanced technology, continuous monitoring, and implementing adaptation and nature-based solutions. Collaboration between academia, universities, researchers, federal and local governments, and rural communities is essential to developing effective preparedness and response strategies.
The Government of Nepal must take the lead in addressing GLOF risks, prioritizing this issue as a critical aspect of disaster management. This includes conducting comprehensive studies of glacial lakes, risk assessments, and the implementation of risk reduction measures. While the cost of reducing the risk of a single glacial lake can range from $2 million to $5 million, depending on its size and location, the investment is necessary to prevent future disasters.
Moreover, global collaboration is vital. Engaging with international academia, universities, donors, and government stakeholders will provide the resources and expertise needed to tackle the GLOF threat. Community engagement is also crucial, as local populations are often the first responders to disasters. Their involvement in research, planning, and decision-making processes will enhance the effectiveness of GLOF preparedness and response efforts.
Conclusion
GLOFs represent a growing threat to Nepal, driven by the accelerating impacts of climate change. The recent incidents in Thame and Mustang serve as stark reminders of the urgency with which this issue must be addressed. The Government of Nepal, in collaboration with researchers, donors, and local communities, must prioritize GLOF disaster management. By taking immediate and coordinated action, Nepal can mitigate the risks posed by GLOFs and protect its vulnerable communities from future disasters.
