Nepal plans to drain four glacial lakes after deadly floods

Nepal will kick off a high-stakes effort this fiscal year to drain four glacial lakes perched high in the mountains, as it scrambles to reduce flood risks, officials said, after a recent disaster that killed more than 1,400.

Rescuers are still searching for more than 5,000 people missing in the border region with China after August’s glacier collapse unleashed landslides and a flash flood that tore through valleys.

“Our aim is to lower the risk of the lakes breaching their natural dams and reduce the risk of downstream floods,” said Subash Tuladhar, an expert with a government research centre tasked with overseeing the new project.

Canals will drain water into nearby rivers in a regulated way, he said, adding that workers faced health risks as a result of the lengthy periods of high-altitude work required, in addition to the dangers of sudden flooding.

Design work and detailed studies targeting the central and eastern lakes of Thulagi, Lower Barun, Lumding Tsho and Hongu II, will begin in the fiscal year that runs until mid-July 2027, authorities said.

The lakes, at heights ranging from 4,050m to 5,483m, rank among Nepal’s most potentially dangerous, the UN Development Programme and the International Centre for Integrated Mountain Development (ICIMOD) said in a 2020 report.

Nepal had the skills and experience required for the US$50-million project to be funded by the Green Climate Fund, the UNDP and the government, added Tuladhar, of Nepal’s Centre for Hydrology and Water Resources Research.

Draining project could take six years

The work of draining “through gated structures” will start after a detailed study, and could take up to six years to complete, said Sanjeeb Baral, the Centre’s executive director.

It will encompass installation of sensors, a flood forecasting and warning system, and efforts to build downstream resilience and prepare communities for the risks.

In similar previous efforts, Nepal lowered by 3m the level of the central Himalayan glacial lake of Tsho Rolpa by in 2000 and that of Imja in the vicinity of Mount Everest, the world’s tallest peak, 10 years ago.

Urgency after recent floods

Nepal’s disaster served as a warning to the world, prime minister Balendra Shah, 36, told the UN in an impassioned speech last month that blamed climate change despite his country’s negligible emissions.

Retreating glaciers, unstable mountain slopes and increasingly unpredictable rivers showed Nepal was paying a heavy price, he added.

Nepal, which has reported about 26 Glacial Lake Outburst Flood events in the past four decades, loses more than 300 lives and property worth millions of dollars to extreme climate events annually on average.

The latest floods devastated a dozen hydroelectric plants, roads, bridges, farms and settlements. Cash-strapped Nepal would need nearly US$5 billion for early recovery, officials have said.

Climate scientists say as temperatures rise glaciers in the Himalayas retreat, leaving behind ​unstable glacial lakes held back by little more than loose rock and ​ice, above valleys home to millions.

Lowering the lakes by 3m would significantly reduce the threat, said Samjwal Ratna Bajracharya, a retired ICIMOD expert on glaciers, glacial lakes and outburst floods.

“They are growing fast, are high up in the Himalayas and could cause outbursts any time, due to earthquakes, avalanches, climatic conditions and unplanned human-induced activity,” he told Reuters.

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