As climate change heats the planet, making rainfall more extreme and accelerating the melting of glaciers, Himalayan nations such as Nepal are facing growing risks from floods, often driven by glacial lake outbursts.

Greater volumes of glacial meltwater are gradually building up in mountain lakes, putting growing pressure on the earth and rock holding them in place. Those can suddenly collapse, spurring huge downstream floods.

While some monitoring equipment and early warning systems are in place to alert downstream communities, a lack of cross-border information sharing among Himalayan nations - among them China, India and Nepal - is handicapping protection efforts, analysts warn.

“Many dangerous glacial lakes are in Tibet. If they burst, it will directly impact Nepal and the damage will be much larger than the Melamchi disaster,” warned Narendra Khanal, a former head of geography at Nepal’s Tribhuvan University.

Dangerous lakes

Northern Nepal borders China for almost 1,400 km (860 miles) and the country’s main rivers - the Koshi, Gandaki and Karnali - flow in from Tibet.

Maps published by the intergovernmental International Centre for Integrated Mountain Development (ICIMOD) and the UN Development Programme (UNDP) show 3,624 glacial lakes along the three river basins in 2020, 2,070 of them in Nepal, 1,509 in China and 45 in India.

Of those, 47 are considered at particular risk of outburst, 25 of them in Tibet, the agencies said.

But little real-time information is shared across international borders on the state of the lakes, even as they grow in size, because formal data sharing mechanisms are largely still not in place, analysts said.

That is raising fears in downstream communities, which are themselves growing in size, that killer floods could arrive with little warning.

“We are not serious regarding the disaster of glacial lake outbursts,” said Deepak K.C., a climate change resilience expert with UNDP in Kathmandu.

The 2016 collapse of a one-hectare glacial lake in Tibet caused US$200 million in damage along the Bhote Koshi river system in Nepal, he said, sweeping away 125 homes and a hydropower plant, though not causing any deaths.

But “other lakes are 200 times larger than that one and can explode at any time. What will be our situation when that happens?” he asked.

Read the full article about flood alerts in Nepal by Thomson Reuters Foundation at Eco-Business.