Question

A devastating flood struck the Chamoli district in Uttarakhand in February 2021 in which many people and livestock lost their lives. There was severe damage to buildings, roads, bridges, and hydel projects, and connectivity to villages was adversely affected. Can you find out the reasons that led to the sudden and unexpected flood?

Answer 1

The sudden flood in Chamoli, Uttarakhand, on 7 February 2021 was mainly caused by a massive rock-and-ice avalanche from Ronti Peak. Scientists found that a huge section of rock and glacier ice broke away from the steep mountain slope and rushed down into the valley.

The falling rock and ice rapidly melted and mixed with water, rocks, mud and debris, creating a very powerful flash flood and debris flow. It travelled through the Ronti Gad, Rishiganga and Dhauliganga valleys, destroying bridges, roads and hydropower projects along the way.

Main reasons:

• Collapse of a large mass of rock and glacier ice from Ronti Peak.
• The steep Himalayan terrain allowed the material to move downhill at great speed.
• The avalanche mixed with water and loose debris, greatly increasing the size and force of the flood.
• Infrastructure located along the narrow river valleys was highly exposed to the sudden flow.

Thus, the Chamoli disaster was not simply a normal rainfall flood or a conventional glacial-lake outburst flood; it was a cascading event triggered by a massive rock-and-ice avalanche.