Nepal to drain four glacial lakes following deadly floods

KUALA LUMPUR, 2 OCTOBER 2026 —

KATHMANDU, Oct 2 — Nepal has launched a high-stakes, $50-million initiative to drain four glacial lakes situated at extreme altitudes in the Himalayas, a critical step to mitigate catastrophic flood risks following a recent disaster that claimed more than 1,400 lives.

The urgency of the operation is underscored by the ongoing humanitarian crisis in the border region with China, where rescuers are still searching for more than 5,000 missing persons. The victims were swept away when an August glacier collapse triggered massive landslides and a flash flood that tore through the valleys below.

In the aftermath of this tragedy, government officials have moved to implement structural interventions designed to lower the water levels of the most dangerous lakes, aiming to prevent a recurrence of such devastating downstream events.

Subash Tuladhar, an expert with the Nepal Centre for Hydrology and Water Resources Research, which is tasked with overseeing the new project, stated that the primary objective is to reduce the likelihood of the lakes breaching their natural dams. “Our aim is to lower the risk of the lakes breaching their natural dams and reduce the risk of downstream floods,” Tuladhar said.

The engineering approach involves the construction of canals that will drain water into nearby rivers in a regulated manner, rather than allowing the lakes to expand unchecked until they overflow or rupture.

The four lakes targeted for immediate intervention are Thulagi, Lower Barun, Lumding Tsho, and Hongu II, located in the central and eastern regions of Nepal. These bodies of water are perched at heights ranging from 4,050 meters (13,280 feet) to 5,483 meters (18,000 feet) above sea level.

According to a 2020 report by the United Nations Development Programme (UNDP) and the International Centre for Integrated Mountain Development (ICIMOD), these lakes rank among the most potentially dangerous in the country due to their size, the instability of their natural dams, and the population density in the valleys below.

The project is funded by a combination of the Green Climate Fund, the UNDP, and the Nepalese government, totaling $50 million. Tuladhar emphasized that Nepal possesses the necessary skills and experience to execute such a complex engineering task. However, he acknowledged that the work presents significant challenges, including the health risks associated with lengthy periods of high-altitude labor and the inherent dangers of sudden flooding during the construction and operation phases.

Sanjeeb Baral, the executive director of the Centre for Hydrology and Water Resources Research, outlined the timeline and technical scope of the operation. Design work and detailed studies for the four lakes will begin in the current fiscal year, which runs until mid-July 2027. The actual draining of the lakes, which will be conducted through gated structures, is expected to commence only after these detailed studies are completed.

Baral indicated that the entire process could take up to six years to complete, reflecting the complexity of working in such a remote and hazardous environment.

Beyond the physical draining of the lakes, the project encompasses a broader suite of risk reduction measures. This includes the installation of sensors to monitor water levels and dam integrity, the development of a flood forecasting and warning system, and initiatives to build downstream resilience. These efforts are designed to prepare local communities for the risks they face, ensuring that even if a breach occurs, the impact on human life and infrastructure is minimized.

Nepal’s recent disaster has served as a stark warning to the global community regarding the impacts of climate change. Prime Minister Balendra Shah, 36, addressed the United Nations last month in an impassioned speech that highlighted the disproportionate burden borne by low-emission countries.

He blamed climate change for the escalating frequency and severity of natural disasters in the Himalayas, noting that retreating glaciers, unstable mountain slopes, and increasingly unpredictable rivers are forcing Nepal to pay a heavy price for global emissions.

The government’s response to the August disaster reflects a shift from reactive disaster management to proactive risk mitigation. The decision to target these specific lakes is based on scientific assessments that identify them as having the highest potential for catastrophic failure. The involvement of international bodies such as the UNDP and the Green Climate Fund underscores the global recognition of the Himalayas as a critical zone for climate adaptation and disaster risk reduction.

Previous efforts by Nepal to manage glacial lake risks provide a precedent for the current project. In 2000, the country successfully lowered the water level of the central Himalayan glacial lake of Tsho Rolpa by 3 meters (10 feet). A decade later, similar measures were taken for the Imja lake, located in the vicinity of Mount Everest, the world’s tallest peak.

These earlier projects demonstrated the feasibility of such interventions and provided valuable technical experience that is now being applied to the new, larger-scale initiative.

The current project is being implemented against a backdrop of ongoing search and rescue operations in the border region with China. The scale of the missing persons list, with more than 5,000 individuals unaccounted for, highlights the devastating potential of glacial lake outburst floods. The flash flood that followed the August glacier collapse tore through valleys, destroying homes and infrastructure, and leaving a trail of destruction that has yet to be fully assessed.

The fiscal year in which the design and study phase begins runs until mid-July 2027, providing a defined window for the initial stages of the project. The $50-million budget is intended to cover the costs of detailed studies, design, construction of canals and gated structures, installation of monitoring equipment, and community resilience programs.

The involvement of the Green Climate Fund signals international support for Nepal’s efforts to adapt to the changing climate, which is exacerbating the risks posed by glacial lakes.

Tuladhar noted that the health risks for workers are a significant concern, given the high altitudes at which the lakes are located. Prolonged exposure to such conditions can lead to serious health issues, and the danger of sudden flooding adds another layer of risk to the construction process. Despite these challenges, the government is committed to proceeding with the project, viewing it as essential for the safety of downstream communities.

The project’s scope includes not only the physical infrastructure but also the development of a flood forecasting and warning system. This system will rely on data from the installed sensors to provide early warnings to communities in the event of a potential breach. By combining structural measures with non-structural approaches, Nepal aims to create a comprehensive risk management framework that can withstand the increasing pressures of climate change.

The 2020 report by the UNDP and ICIMOD that identified these lakes as high-risk remains a key reference for the current project. The report highlighted the growing threat of GLOFs in the Himalayas, driven by glacial retreat and the accumulation of water in moraine-dammed lakes. The current initiative is a direct response to the findings of that report, translating scientific assessments into concrete action.

Prime Minister Shah’s speech at the United Nations last month drew attention to the global nature of the crisis. By blaming climate change despite Nepal’s negligible emissions, he sought to highlight the inequities of the climate crisis and the need for international support for vulnerable countries. The $50-million project is a tangible example of the kind of support that is needed to help Nepal and other Himalayan nations adapt to the changing climate.

The work of draining the lakes through gated structures is expected to be a long-term endeavor, with Baral estimating a completion timeline of up to six years. This timeline reflects the complexity of the engineering challenges involved and the need for careful planning and execution. The project will require close coordination between the government, international partners, and local communities to ensure its success.

As Nepal moves forward with this ambitious project, it faces the dual challenge of managing the immediate aftermath of the August disaster and preparing for future risks. The search for the more than 5,000 missing persons continues, a grim reminder of the human cost of glacial lake outburst floods.

The government’s decision to invest in structural risk reduction measures is a testament to its determination to protect its people and its environment in the face of a changing climate.

The involvement of the Green Climate Fund in the project underscores the international community’s recognition of the importance of climate adaptation in the Himalayas. By supporting Nepal’s efforts to drain these dangerous lakes, the fund is helping to build resilience in one of the most vulnerable regions of the world.

The project is expected to serve as a model for other countries facing similar challenges, demonstrating the feasibility and importance of proactive risk management in the context of climate change.

The detailed studies that will begin this fiscal year are a crucial first step in the project. These studies will provide the scientific basis for the design and construction of the canals and gated structures. The data collected will also inform the development of the flood forecasting and warning system, ensuring that it is tailored to the specific risks posed by each of the four lakes.

The project’s success will depend on the quality of these studies and the effectiveness of the subsequent implementation.

Nepal’s experience with previous glacial lake management projects, such as Tsho Rolpa and Imja, provides a valuable foundation for the current initiative. The lessons learned from these earlier efforts will be applied to the new project, helping to mitigate risks and improve outcomes. The government’s commitment to this project reflects its recognition of the urgent need to address the growing threat of glacial lake outburst floods in the Himalayas.

The project’s focus on community resilience is a key aspect of its design. By preparing local communities for the risks they face, the government aims to reduce the human impact of any future disasters. This includes education, training, and the development of evacuation plans. The installation of sensors and the development of a warning system will provide communities with the information they need to take protective action in the event of a potential breach.

The $50-million budget for the project is a significant investment for Nepal, reflecting the scale of the challenge it faces. The funding from the Green Climate Fund, the UNDP, and the government ensures that the project has the resources it needs to succeed.

The international support for this initiative is a sign of the growing recognition of the importance of climate adaptation in the Himalayas and the need for global cooperation to address the challenges posed by climate change.

As the project moves into its design and study phase, Nepal is taking a proactive step to reduce the risk of catastrophic floods in the region. The draining of the four glacial lakes is a complex and challenging task, but one that is essential for the safety of downstream communities.

The government’s commitment to this project, supported by international partners, offers hope that Nepal can mitigate the risks posed by climate change and protect its people and its environment.

The ongoing search for the missing persons from the August disaster serves as a constant reminder of the stakes involved. The government’s efforts to drain the lakes are not just an engineering project, but a humanitarian imperative. By reducing the risk of future disasters, Nepal is working to ensure that such tragedies do not happen again. The project is a testament to the country’s resilience and its determination to adapt to the changing climate.

The involvement of experts from the Nepal Centre for Hydrology and Water Resources Research is crucial to the success of the project.