Nepal flash floods: Why the avalanche resembles Chamoli, but with greater impact

The recent flash floods in Nepal's Rasuwa district have been compared to the 2021 Chamoli avalanche-induced flood in Uttarakhand, India, though the impact this time is far greater. Farooq Azam, a professor at IIT Indore, stated that while the Chamoli disaster was triggered by a glacial lake outburst flood (GLOF), the Nepal event appears to be caused by an ice and rock avalanche, similar to the 2013 Kedarnath disaster.

Both Chamoli and Kedarnath resulted in devastating downstream surges, causing immense damage to mountainous rivers and leading to flash floods.

The Nepal disaster has occurred during the peak monsoon season, when the rivers are already saturated, exacerbating the situation. Azam explained that the combination of a large ice and snow avalanche and existing saturated conditions has created a more destructive scenario. He emphasized that the Himalayan region is fragile, and such events lead to a cascading disaster, where the surging river erodes banks and slopes, leading to more sediment and debris being carried downstream.

In Sikkim, a similar event in 2023 triggered by a glacial lake outburst flood resulted in a massive 270 million cubic meters of sediment being eroded. The National Disaster Management Authority of Nepal has initiated a comprehensive study of glacial lakes to strengthen their boundaries and install sensors to detect potential leaks and water accumulation, aiming to prevent future disasters.