The Calamitous Consequence of Cloudbursts in Himachal Pradesh: Understanding and Mitigation

I. Understanding Cloudbursts - An Intense and Sudden Menace

A. What Exactly is a Cloudburst?

- Defined by the India Meteorological Department (IMD), a cloudburst happens when more than 10 cm of rain abruptly falls within an hour over a small area of around 10 sq km.

- They occur predominantly in mountainous regions, particularly in the Himalayas.

- In the Indian subcontinent, cloudbursts could be attributed to monsoon clouds drifting northwards from the Bay of Bengal or the Arabian Sea which reach the plains and subsequently the mountains, resulting in heavy rainfall.

B. What Causes Cloudbursts?

- The phenomenon is initiated when powerful upward currents of hot air obstruct rainfall, leading to enlargement of raindrops and subsequent formation of smaller drops underneath them.

- This effect contributes to a substantial accumulation of water in the atmosphere that is released abruptly as upward currents weaken, causing a cloudburst.

- The Indian subcontinent's complex topography and the orographic lifting process play crucial roles in the occurrence of cloudbursts.

C. Cloudbursts Vs Rainfall

- While rain is a common phenomenon, cloudbursts are sudden and heavy rainstorms.

- The term 'cloudburst' is only used when rain is more than 10 cm per hour. 

D. Prediction and Examples of Cloudbursts

- The anticipation of cloudbursts is a challenge due to their unpredictable and sudden nature, which can only be detected with expensive, finely netted radars.

- Prominent examples in India include devastating cloudbursts in Uttarakhand (July 2021) and Himachal Pradesh (August 2020) which led to flash floods, landslides, and widespread infrastructural damage.

II. The Catastrophic Aftermath of Cloudbursts

A. Flash Floods

- Flash floods are sudden local surges in water levels during or following intense rainfall, typically caused by thunderstorms.

- Factors such as rainfall intensity, location, land usage, topography, vegetation, soil type, and water content influence the onset and location of flash floods.

B. Landslides

- Landslides are mass movements of materials like rocks or earth down a slope.

- Heavy rainfall, erosion, and weathering can trigger landslides.

C. Mudflows

- Mudflows feature high-density water flow, with significant amounts of suspended particles and silt.

III. Relationship between Climate Change and Cloudbursts 

- Increased atmospheric moisture, changes in precipitation patterns, altered atmospheric stability, and glacier retreat are amongst the impacts of climate change that can potentially increase the occurrence of cloudbursts.

IV. Proposed Measures to Alleviate the Devastating Impact of Cloudbursts

- Effective early warning systems, resilient urban planning and infrastructure, watershed management, reforestation, and education on cloudburst risks can help mitigate the disastrous effects of cloudbursts.

- Sustainable land use practices and collaborating with neighbouring countries and international organisations can also significantly contribute to managing cloudburst impacts.