Uttarkashi Cloudburst

Uttarkashi Cloudburst : Recently, Uttarakhand’s Uttarkashi district was hit by a devastating flash flood, reportedly triggered by a cloudburst and intense rainfall. The sudden surge in the Kheer Ganga River swept through Dharali town, causing extensive damage and destruction.

• About Cloudburst : According to the India Meteorological Department (IMD), a cloudburst occurs when rainfall exceeds 100 mm in an hour over a specific area.

o Link to Climate Change: Global warming increases atmospheric moisture-holding capacity. This leads to more intense, erratic, and sudden rainfall, making cloudbursts more frequent and severe.

o Prediction Challenges: Cloudbursts are highly localised events, usually affecting areas around 10 km × 10 km, making them difficult to predict accurately.

• How Cloudbursts Happen : Orographic Lift: In hilly regions, warm air currents push moisture-laden clouds upward. This upward movement (orographic lift) is a key reason cloudbursts are more frequent in mountainous terrain.

o Growth of Droplets: As clouds rise higher, water droplets grow larger and more form. Lightning within these clouds often delays rainfall, increasing moisture load.

o Sudden Downpour: When clouds can no longer hold the excess moisture, they burst, releasing intense rainfall over a small area.

• Hazards Triggered by Cloudbursts: Flash Floods: Torrential rain causes immediate overflow of rivers and streams, leading to destructive flash floods.

o Landslides: Heavy rainfall loosens soil on slopes, triggering landslides that block roads and damage infrastructure.

o Mudflows: A fast-moving mixture of water, soil, and debris engulfs buildings and fields, causing severe destruction.

o Land Subsidence:  Excess water pressure weakens the ground, leading to sudden collapses such as cracks, sinkholes, or hillside failure.