Nepal has announced plans to drain four glacial lakes located high in the Himalayas to reduce the risk of catastrophic floods following a deadly disaster in August that claimed over 1,400 lives. Authorities revealed that this initiative will begin in the current fiscal year, which runs through mid-July 2027, aiming to forestall breaches in the lakes’ natural dams and mitigate downstream flooding hazards.
The lakes targeted for the project—Thulagi, Lower Barun, Lumding Tsho, and Hongu III—are situated at elevations ranging from 4,050 meters to 5,483 meters and identified as some of the most dangerous in Nepal. These findings were highlighted in a 2020 report by the United Nations Development Programme (UNDP) and the International Centre for Integrated Mountain Development (ICIMOD). The recent flash flood was triggered by a glacier collapse near the Nepal-China border, which unleashed landslides and inundated several valleys. More than 5,000 people remain missing in the aftermath.
Subash Tuladhar, a hydrology expert with Nepal’s Centre for Hydrology and Water Resources Research, said the project involves creating canals to slowly and safely drain excess water into nearby rivers. While the work will reduce flood risks, he emphasized that it poses significant health and safety challenges due to the prolonged high-altitude conditions and the potential for sudden flooding. Initial efforts will focus on detailed design and studies of the lakes before construction begins.
The estimated cost of the project is approximately US$50 million, with funding expected from the Green Climate Fund, the UNDP, and the Nepalese government. Sanjeeb Baral, executive director of the research center, noted that the project may take up to six years to complete and will include the installation of gated drainage structures, sensors, and a flood forecasting and warning system. Additionally, it will involve enhancing downstream community resilience and preparedness.
Nepal has previous experience with similar interventions, including lowering the water level of the Tsho Rolpa glacial lake by three meters in 2000 and reducing the water level of Imja Lake near Mount Everest by 3.4 meters in 2016. Experts say that lowering the lakes by around three meters can significantly diminish the likelihood of outburst floods.
The urgency of the project stems from the increasing frequency and severity of glacial lake outburst floods (GLOFs) fueled by climate change. According to Nepalese officials, the steep retreat of glaciers and destabilization of mountain slopes are leaving behind fragile natural dams that trap vast amounts of water. Nepal has recorded approximately 26 GLOF events over the past 40 years, resulting in more than 300 deaths annually on average, along with widespread damage to infrastructure and agriculture.
The most recent flood destroyed numerous hydroelectric plants, roads, bridges, farms, and settlements, exacerbating the country’s economic challenges. Officials estimate that Nepal will require nearly US$5 billion for early recovery efforts. In a September address to the United Nations, Prime Minister Balendra Shah emphasized that although Nepal’s greenhouse gas emissions are minimal, the country is disproportionately bearing the consequences of global climate change, underscoring the need for urgent action to protect vulnerable mountain communities.