Breach in temporary lake may have caused Uttarakhand flash flood

Latest evidence in Uttarakhand flash floods suggests the incident could be a result of breaking away of a temporary lake, formed due to landslides or avalanches. Scientists define it as Landslide Lake Outburst Flood (LLOF).

Satellite images show the flash flood could be a result of snowfall on a mountain nearby. The snow may have resulted in an avalanche that flooded the rivers with 3-4 million cubic metres of water.

Santosh Rai, head of the Glaciology and Hydrology division at the Dehradun-based Wadia Institute of Himalayan Geology, told Indian Express, “Satellite images show there was no snow on February 2 in the valley, but very heavy snowfall was witnessed on February 5 and 6. This fresh snow started melting on February 7, which led to the slumping of the snow bank, and a subsequent avalanche. As the snow bank travelled down the valley, it gained momentum and kinetic energy, thus increasing the amount of water and soil on the way.”

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“A landslide or snow avalanche can create obstructions in the normal path of a flowing river or stream, which results in the formation of a temporary pool, or a dam-like situation. When this obstruction finally gives way to the force of accumulating water, it creates a situation similar to a lake burst. In the case of an avalanche, snow adds to the volume of water,” a member of the DRDO team investigating the natural calamity told IE.

At first it looked like the flash flood was a result of a Glacial Lake Outburst Flood, which is mainly attributed to climate change.

The DRDO probe team has yet to provide conclusive evidence to back its claims. The team may reach the exact location only by next Monday.