Cloudburst in Uttarakhand

• 01 Jul 2025

Why in News? 

A cloudburst in Uttarkashi, Uttarakhand caused landslides, disrupted key pilgrimage routes, and left several workers missing. 

• Districts prone to flash floods and landslides have been placed on high alert.

Key Points

• About Cloudburst: 
  • A cloudburst is a sudden, intense rainstorm that results in more than 10 cm of rain in less than an hour over a small area (approximately 10 km²).   
  • It can also be accompanied by hail and thunder. Cloudbursts are common in mountainous areas, especially in the Himalayas.  
  • Due to their localised nature, cloudbursts are hard to predict or detect but can unleash sudden, devastating rainfall, leading to flash floods and landslides. 

• Landslide: 
  • Definition: A landslide is the downward movement of rock, soil, or debris on a slope due to gravity.  
    • It is a form of mass wasting, where earth materials move down a slope under the influence of gravity. 
  • Causes: Natural factors like heavy rainfall, earthquakes, and water seepage weaken slopes, while human activities such as deforestation and construction increase risks. Geological factors, such as soil composition and terrain, also affect slope stability and can lead to landslides. 
• Flash Floods:  
  • Definition: Flash floods are sudden increases in water levels during or immediately after intense rainfall.  
    • They are highly localized and short-lived events, typically occurring within 6 hours of rainfall.  
  • Causes: Flash floods are primarily caused by intense rainfall that overwhelms the soil’s absorption capacity and drainage systems.   
    • Apart from heavy rain, flash floods can also result from rapid snowmelt due to sudden temperature rise, dam or levee breaches, ice or debris jams, and sudden glacial lake outbursts.  
    • Additionally, urbanisation with impervious surfaces like roads and buildings increase runoff, reducing water absorption and intensifying flood risks.