This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: On Aug. 26, a rock and ice avalanche triggered a huge flood that swept through a steep valley in Nepal, leaving thousands dead and missing. It was an extreme example of a growing problem across the Himalayas.
As glaciers melt, glacial lakes expand and mountain permafrost thaws, the risks from floods, landslides and other high-mountain hazards are increasing. At the same time, more people and infrastructure are moving into the valleys where these hazards are most likely to strike. Our new study shows how quickly this exposure is growing.
We focused on Nepal and the catchment areas of rivers that drain into Nepal. In that region, between 2016 and 2023, the built-up areas potentially exposed to flooding increased by 46%. Across the Nepalese Himalayas, we estimate almost 300,000 people live in these flood-prone areas, including more than 100,000 downstream of glacial lakes.
Those lakes, formed in depressions carved out by retreating glaciers, are a particular risk because they can suddenly breach, sending floodwaters crashing down steep valleys. So far, scientists have largely focused on what's causing these hazards: the melting glaciers, landslides, torrential monsoon rains and so on. Far less attention has been paid to exposure: the people, buildings and infrastructure potentially at risk.
Our results reveal a concerning trend of continued urbanization in areas susceptible to flooding. This is partly due to the geography. In the Himalayas, valley floors are some of the only flat and accessible places to build roads, settlements and other infrastructure.
Rivers also provide natural routes through the mountains—the recent disaster struck Nepal's primary trade route to China running along the Bhotekoshi–Trishuli rivers, for instance. Yet as trade and tourism grow, these corridors attract new roads, tracks, lodges, hydropower projects and more. And once a road connects a valley, other development often follows, including homes, schools and health care facilities.
Extract — continue reading at the source.
