A new study by researchers at IIT Roorkee has identified the Alaknanda River in Uttarakhand as being particularly vulnerable to natural dams caused by landslides. These dams can lead to devastating floods when they break.
Here's a simplified explanation:
What are Landslide Lake Outburst Floods (LLOFs)?
A landslide blocks a river, creating a natural dam.
Water builds up behind the dam, forming a lake.
Eventually, the dam breaks, releasing a large amount of water suddenly and causing a flood.
What causes landslides that create these dams?
Unstable slopes.
Heavy rainfall.
Earthquakes.
Climate change is making these events more frequent in the Himalayas.
Why is the Alaknanda River especially at risk? Because of the steep valleys and gorges in Uttarakhand.
Which areas are most affected? Chamoli, Rudraprayag, and Uttarkashi districts (all in the Garhwal region of Uttarakhand).
What is an example of a past LLOF in the area? The Gohna Tal incident in Chamoli.
A landslide created Gohna Lake in 1893.
The dam partially broke in 1894 and completely in 1970, causing flooding as far away as Haridwar.
How far back do these events go? Landslide dams have been forming in Uttarakhand since the Last Glacial Maximum (about 29,000 to 19,000 years ago).
When are these events most likely to happen? August, during the monsoon season (heavy rains).
Why are these events becoming more common?
Climate change.
Human activities like deforestation (cutting down forests) and road construction.
What are the challenges in managing these disasters?
Even though there haven't been many major incidents since 2018, it's difficult to predict when these dams will break.
Heavy rainfall and cloudbursts are the main triggers.
Debris slides (landslides containing rocks and soil) are the most common type of landslide that blocks rivers in Uttarakhand.
What needs to be done in the future?
Better disaster management strategies are needed.
It's important to understand how these landslide dams work.
Better monitoring and preparedness are needed to protect communities from floods.
Key Terms/Acronyms:
LLOFs: Landslide Lake Outburst Floods.
Key Places:
Alaknanda River: The river at high risk.
Uttarakhand: The state in India where these events occur.
Garhwal: A region within Uttarakhand.
Chamoli, Rudraprayag, Uttarkashi: Districts in Uttarakhand most affected by landslide dams.
Gohna Tal: The site of a major past LLOF event.
In simple terms: Landslides can block rivers, creating natural dams that can cause dangerous floods.
A new study shows that the Alaknanda River in Uttarakhand is especially at risk. Climate change and human activities are making these events more common. It's important to improve monitoring and planning to protect people from future floods.