Building boom puts 300,000 people in the path of potential Himalayan disasters

A peer-reviewed study found that construction expanded sharply in parts of northern Nepal, south-eastern Tibet and Uttarakhand between 2016 and 2023. Built-up land in high-risk areas grew by about 45%. At least 300,000 people may now live in the path of potential disasters. The findings matter because construction is placing more homes, businesses and infrastructure where floods, landslides and debris flows can strike.

The increase was greatest around glacial lakes, where development rose by almost 78%. Researchers examined land within 50 kilometres downstream of Himalayan rivers and around about 1,360 glacial lakes. They counted buildings within 50 vertical metres of a river or lake surface as being at risk. Tourism facilities, infrastructure and real estate all expanded in these zones.

The true number could be higher because neighbouring risky areas were not included. The study also came before devastating floods in Nepal left more than 1,400 people dead and thousands missing. Researchers warn that decisions made today will shape disaster risk for decades.

A glacial lake outburst flood occurs when water held in a glacial lake suddenly escapes, often after the lake expands or its natural barrier fails. The released water can rush down a steep valley with little warning. It matters because communities, roads, bridges and buildings downstream may be overwhelmed before people can respond.

The article explains that warming is melting glaciers, icefields and snowpacks faster. Meltwater fills and enlarges glacial lakes until they burst. The flood can also destabilise mountain slopes and carry rock, ice and mud downstream. Nepal has documented around 30 such events since 1940, showing that the danger is recurring rather than theoretical.

Communities near glacier-fed rivers face constant uncertainty. A hotel owner near the Modi River fears flooding if a glacier collapses or a glacial lake bursts. Development around lakes and rivers increases exposure, while the study’s 50-metre building-risk measure may miss structures reached by unusually high water and debris.

The study estimates that at least 300,000 people could now be living in the path of Himalayan disasters. It does not provide a total number of threatened buildings. Instead, researchers measured how much built-up land expanded in selected high-risk areas and identified buildings close to rivers and glacial lakes.

Across northern Nepal, south-eastern Tibet and part of Uttarakhand, built-up land in high-risk zones grew about 45% between 2016 and 2023. In places especially exposed to glacial-lake flooding, development increased almost 78%. The researchers examined areas up to 50 kilometres downstream from rivers and around about 1,360 glacial lakes.

Their estimate is not a complete regional total. Neighbouring areas with similar hazards were excluded, so more people and buildings may be exposed. The study classified buildings within 50 vertical metres of a river or lake surface as at risk, but the article notes that floodwater and debris rose much higher in some locations.

Development near Himalayan rivers and glacial lakes is not limited to one type of construction. Researchers found expanding tourism facilities, infrastructure and real estate. These include hotels, homestays, settlements, roads and other facilities serving visitors. Hydropower construction has also increased around the Bhotekoshi and Trishuli rivers.

Pokhara shows the pattern clearly. The tourism hub has grown greatly over 30 years, while old buildings remain only about five metres from the Seti Gandaki River. Settlements have also expanded along rivers in the Annapurna trekking region. In some northern Indian valleys, tourism development is linked to major pilgrimage destinations.

Local observers say tourism businesses and investors promoted some sites without properly factoring in risks. The Hotel Association Pokhara president acknowledged that tourism expanded without proper planning. As more buildings occupy river valleys, floods, landslides and glacial outbursts can affect more people and disrupt bridges, homes, hotels and businesses.

When Himalayan rivers rise, communities downstream can face sudden destruction. Floods may damage or bury homes, sweep away bridges and leave people missing. Landslides can block or overwhelm settlements, while glacial floods may send powerful water and debris through valleys. These impacts can also close tourism businesses and threaten local incomes.

A flood along the Budhi Gandaki River on 11 October damaged 200 houses, swept away five bridges and left five people missing. In Rasuwa district, locals reported that the river rose by 70 metres during catastrophic flooding on 26 August. Buildings that were not close to the riverbank were still hit and buried by debris and sludge.

The human and economic effects can continue after the water recedes. A homestay operator in the Annapurna region said only five of his usual 20 rooms were occupied after recent disasters. The article reports that August floods in Nepal killed more than 1,400 people and left thousands missing, underlining the scale of the danger.

People continue building near rivers because these areas support tourism, settlements, transport and business. Flat land is valuable in steep mountain valleys, and river corridors attract hotels, homes, roads and hydropower projects. Tourism investors also promote scenic locations and pilgrimage routes, sometimes without fully considering flood and landslide risks.

Pokhara illustrates the conflict. The city has expanded to serve a huge increase in visitors, but many old buildings stand just five metres from the Seti Gandaki River. New rules require greater distance from riverbanks, yet moving existing buildings is difficult. The mayor calls deciding where to move them, and how, the real challenge.

Local tourism leaders acknowledge that expansion occurred without proper planning and was promoted haphazardly. Economic pressures therefore continue alongside known hazards. Researchers warn that development decisions made now will shape disaster risk for decades, while awareness efforts are trying to reach tourism entrepreneurs and investors before disasters strike.

Climate change increases Himalayan disaster risks by rapidly warming the region. Scientists cited in the article say the Himalayas are warming at twice the global rate. This speeds the melting of glaciers, icefields and snowpacks, and thaws ground that normally stays frozen. Those changes can weaken mountain slopes and alter how water moves through valleys.

Meltwater fills and enlarges glacial lakes, increasing the chance that they will burst and produce deadly floods. Warming also causes rain to fall at high elevations where snow once fell. Rain can destabilise slopes and contribute to landslides, rockfalls and icefalls. Earthquakes frequently shake the same mountain terrain, adding another source of instability.

The danger reaches far downstream, where growing settlements and infrastructure now occupy river valleys. Nepal has recorded around 30 glacial lake outburst events since 1940. Researchers warn that current construction choices will influence disaster risk for decades, while the study’s findings may understate exposure because nearby regions were not analysed.