A ‘Himalayan tsunami' has just devastated Nepal. It should be a wake-up call

Independent

16-07-2025

Up until a disastrous day earlier this month, more than 150 trucks crossed daily over a border bridge between Nepal and China. Known by locals as the Miteri Pul (Friendship Bridge), the Rasuwagadhi crossing served as the main trade route between the two countries, with over $50m of goods passing over it last year alone.
But on the 8 July, floodwaters tore through northern Nepal's Rasuwa district, sweeping away parts of this critical border highway. According to the National Disaster Risk Reduction & Management Authority, seven people lost their lives, and 20 were missing, including six Chinese nationals.
The Chinese nationals were working on a 200 megawatt hydro project in the Tirsuli River, which was also damaged by the floods. Initial estimates suggest Nepal has sustained losses of over $100m in the incident as a whole.
Mina Poudel, a hotel owner near the Nepal–China checkpoint, says she was jolted awake at 2am by violent tremors.
"Thinking it was an earthquake, we suddenly got up and ran out of the house," she told The Independent by phone. "Everyone was shouting. Then from a safe distance, we saw water rising in the Bhotekoshi. That's when we knew it was a flood."
By 4am, she said, the torrent had swept away a Chinese workers' camp and a cargo vehicle. Her hotel, once serving more than 70 customers daily, now stands empty. "The border is closed. The businesspeople are gone. So are the tourists."
Scientists have determined that the cause was an outburst from a glacial lake. According to Jakob Steiner, a postdoctoral fellow at the University of Graz (Austria), and Amrit Thapa, a PhD student at the University of Alaska Fairbanks, the glacial lake had formed in March, approximately 35km upstream from the border inside Chinese territory.
Their research shows that ponds of liquid water sitting on top of the glacier began growing from March, then suddenly started expanding rapidly in June. All the ponds coalesced into a single, massive lake measuring 638 square km by 7 July, before bursting out into the valley below, draining a third of the lake's area in just 24 hours.
Glacial lake outburst floods (GLOFs) have become increasingly common in Nepal, driven by rapid warming in the Himalayas. Nepal's Department of Hydrology and Meteorology reports that temperatures in the Himalayan region have increased by 0.42C per decade between 2008 and 2018 – nearly double the global average.
glaciers between 1977 and 2010, according to researchers, contributing to a substantial decline in freshwater reserves in the Himalayas. In the Himalayan region, the number of glacial lakes and their area are rapidly increasing.
A study by ICIMOD found that the number of glacial lakes in Nepal increased by 154 per cent between 1977 and 2017, while their total area expanded by about 46 per cent. Nepal currently shares more than 1,500km of mountainous border with China, and many of its rivers, including the Bhotekoshi, originate in Tibet.
A 2020 survey by ICIMOD and the UN Development Programme identified 3,624 glacial lakes across the region's three river basins. Of these, 47 were found to be at high risk of bursting, with 25 located in Tibet. One of the most dangerous is Thulagi Lake in Manang District, which holds an estimated 36 million cubic metres of water. If it were to burst, the resulting flood could impact over 160,000 people downstream and cause damage estimated at $415m.
Basanta Raj Adhikari, assistant professor of engineering geology and disaster risk reduction at the Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University, said that the Rasuwagadhi flood was neither the first nor the last. He warned that Nepal will face more major GLOFs in the future, resulting in significant losses.
'The increasing global temperature has a direct effect on the Himalayas, where the formation of glacial lakes [has been] increasing in recent years,' he said. 'These glacial lakes might turn into GLOFs in changing conditions, as we are witnessing.'
Over the past five years, Nepal has faced repeated incidents of severe floods originating from the Himalayan region, causing significant damage and disruption.
In May 2025, a glacial lake outburst occurred near the Limi Valley in Humla district, in western Nepal near the China border. According to Shiva Baskota, senior geologist at the Department of Mines and Geology, three glacial ponds located at an altitude of 4,400 metres melted. The water flowed out rapidly, triggering a flood.
As a result, more than 20 families were displaced from their homes.
On 16 August 2024, a similar flood hit the popular tourist village of Thame, which was caused by another glacial lake burst. Two lakes overflowed, and the water rushed nearly 10 kilometres downhill, striking the village that has been home to legendary Sherpa climbers like Tenzing Norgay. The flood destroyed 23 homes and damaged 40 more, according to Khumbu Pasang Lhamu Rural Municipality.
In 2021, a glacial lake collapsed near the Tibetan border in Sindhupalchok district. This event claimed 24 lives and caused damage worth about $905m, including the destruction of 570 homes, according to Nepal's National Disaster Risk Reduction and Management Authority.
In 2016, Gongbatongshacuo Lake in Tibet burst, sending a massive flood down the Bhote Koshi River in northern Sindhupalchok. The flood swept away 20 houses, a boarding school, and part of a customs office. It also damaged many buildings, a hydropower plant, and roads, including a major highway connecting Nepal and China.
Ranjan Kumar Dahal, an engineering geologist at Tribhuvan University in Nepal, said that the latest devastating event should raise 'serious concerns' and serve as a reminder that 'Himalayan tsunamis' are becoming more frequent and intense, and they are not going to stop anytime soon.
Pema Gyamtsho, director general of ICIMOD, said that it was an absolute certainty that global temperature rises are driving increases in the frequency, ferocity, and complexity of mountain hazards. 'In June alone, three lake outbursts have torn through our region, on top of horrific floods in India and Pakistan; tragically confirming our Monsoon Outlook's predictions of a high-hazard summer.'