Nepal will study four glacial lakes for draining, a job that could take six years

Nepal will start design work this fiscal year on a plan to drain four glacial lakes, Thulagi, Lower Barun, Lumding Tsho and Hongu II, after an August glacier collapse killed more than 1,400 people and left more than 5,000 missing in the border region with China. The project is costed at 50 million dollars and could take six years.

Subash Tuladhar, an expert at the government research centre that will oversee the work, said the aim is to lower the risk that the lakes breach their natural dams and flood the valleys below. Canals would carry water into nearby rivers in a controlled way. He said workers will face the health cost of long periods at altitude, and the risk of a sudden flood while they are on the dam. Sanjeeb Baral, the centre's executive director, said draining through gated structures will start only after a detailed study, and could take up to six years. The study and design for the central and eastern lakes will begin in the fiscal year that runs to mid-July 2027.

The money is to come from the Green Climate Fund, the UN Development Programme and the government. Tuladhar said Nepal has the skill and the experience to run a project of that size. The package also includes sensors, a flood forecast and warning system, and work to prepare communities downstream. Lowering a lake by about three metres can cut the flood threat sharply, glaciologist Samjwal Ratna Bajracharya told The Straits Times.

The four names are the part of the announcement that can be checked against a map. Thulagi lies below Mount Manaslu in the central Himalaya. Lower Barun, Lumding Tsho and Hongu II sit in the eastern ranges, in the drainage that feeds the Dudh Koshi and neighbouring rivers. Imja Tsho, the lake most often photographed above Dingboche, is not on this list. The government has picked a set rather than the single famous lake. That choice spreads the work across two regions and two river systems, which is why Baral's six-year figure is plausible even before the first gate is built.

August is the reason the fiscal year has been pulled forward. A glacier collapse sent landslides and a flash flood through valleys on the China border. Rescuers are still searching for more than 5,000 people. The death toll, more than 1,400, is already larger than most Himalayan outburst floods on record. A glacial lake outburst is a different mechanism from a collapsing glacier tongue, but the same valleys take the water. Draining a lake does not stabilise a hanging glacier. It reduces the volume that can be released if a moraine dam fails, which is the failure Tuladhar named.

The engineering is ordinary in outline and hard in place. A gated outlet cut through or around a moraine lets operators hold the lake lower than the natural spill point. Three metres, the figure Bajracharya gave, is a small change in height and a large change in pressure on a loose dam of ice and rock. The difficulty is access. These lakes sit above the roads. Materials move by trail, and the working season is short. Tuladhar's warning about altitude and sudden floods is the operational constraint, not a footnote. A crew on a moraine during the monsoon is in the path of the event it is trying to prevent.

Nepal has drained or lowered lakes before, including work at Tsho Rolpa and studies at Imja. The new project differs in scale: four lakes, a named funder set, and a clock that starts in the current fiscal year rather than after another disaster. What it does not yet have is a published order of work. If Thulagi is first, the central valleys get the earlier protection. If the eastern three are first, the Dudh Koshi system does. Baral said the gated work waits on the study. Until that study ranks the four lakes by volume, dam condition and people living below, the 50 million dollars is a ceiling, not a schedule.

The missing are still the larger number. More than 5,000 people have not been accounted for since August, against more than 1,400 confirmed dead. A six-year drain does not change that search. It is the government's answer to the next lake, not to the last flood.