More than 300,000 people at risk of a major Himalayan disaster as construction rises 45 percent, study finds

At least 300,000 people in parts of the Himalayan region live in areas exposed to the risk of a major natural disaster, according to a new research report. The areas at risk include northern Nepal, parts of southeastern Tibet and various parts of India's Uttarakhand state.

According to the study, construction is growing rapidly in these disaster-prone areas. Between 2016 and 2023, the amount of land covered by buildings and other structures in these areas increased by about 45 percent. The study, published in Scientific Reports, has been peer reviewed.

Construction has grown even faster in areas at risk of flooding from glacial lakes. In the same period, building in those areas rose by about 78 percent, the study says.

Nine researchers from Britain, Nepal and India studied areas up to 50 kilometres from the banks of Himalayan rivers and the surroundings of about 1,360 glacial lakes. They found extensive construction in these areas, including tourism infrastructure, other infrastructure and housing.

The researchers say the true number of people at risk could be much higher, because the study covered only one specific region; nearby areas facing the same kind of risk were not included.

The study treated every building within 50 metres in elevation of a river or glacial lake water level as at risk. But residents of Nepal's Rasuwa district reported that during the August 26 flood, river water rose as high as 70 metres in some places; buildings well away from the riverbank were inundated, and many were buried under debris and mud.

The research was carried out before the devastating floods in Nepal in August, in which more than 1,400 people died and thousands went missing. Later, on October 11, flooding in the Budhi Gandaki river damaged 200 houses, washed away five bridges and left five people missing.

One major reason the risk is growing is rising temperatures in the Himalayan region. Scientists say temperatures there are rising at twice the global average rate. Glaciers and snow are melting faster, mountain slopes can weaken, and glacial lakes keep growing until a lake bursts and causes a catastrophic flood. About 30 such events have been recorded in Nepal since 1940. Higher temperatures also mean rain now falls instead of snow at high elevations, increasing the risk of slope collapse and falling rock and ice.

The tourist city of Pokhara features in the study as an example. Its mayor, Dhan Raj Acharya, said managing the risk from the Seti Gandaki river, which flows through the middle of the city, is the biggest challenge; many old buildings on the riverbank stand only five metres from the river, although new rules require buildings to be constructed further away. Where and how those buildings would be moved is the real challenge, he said.

Furpa Shiring Lama runs a homestay in the Annapurna trekking area. In a normal peak trekking season all 20 of his rooms are full of guests, but now only five rooms are occupied. He said he had never seen such disasters in more than 40 years in the business. Krishna Gauchhan, who runs a hotel near the Modi river, also said he lives with the fear of flooding if a glacier bursts or a glacial lake suddenly drains.

The study's lead author, C. Scott Watson, a glacier specialist at the University of Leeds, warned that populations in river valleys are steadily growing and that development decisions taken today will affect disaster risk for decades to come. Construction of hydropower projects around the Bhotekoshi and Trishuli rivers has also risen significantly.

Nepal's Prime Minister Balen Shah recently raised the risks of climate change in his address to the UN General Assembly, saying Nepal is paying a high price for a crisis it played no role in creating, and that every major disaster threatens to wipe out years of development work. Alton Byers, a mountain geographer at the University of Colorado who was not involved in the study, said it could help improve early warning systems and other risk-reduction measures.

Dharma Raj Upreti, chief executive of Nepal's National Disaster Risk Reduction and Management Authority, said settlement within 15 metres of the riverbank in the Rasuwa-Bhotekoshi area will soon be banned, and similar rules will be introduced in other river valleys. India's Uttarakhand government also approved new rules on October 12 to control land use and construction in flood-prone areas. Basanta Raj Adhikari, director of Tribhuvan University's Centre for Disaster Studies, suggested setting insurance premiums according to risk levels to encourage people to build in lower-risk areas.