Cloudburst is a localized event of intense rainfall activity. It is most common in hilly regions, but can also occur in plains. The specific definition of a cloudburst is rainfall of 10 cm or more in an hour over a roughly 10 km x 10 km area. During a cloudburst event, a place receives about 10% of the annual rainfall within an hour.
Cloudbursts are common events, particularly during the monsoon months. The local topology, wind systems, and temperature gradients between the lower and upper atmosphere facilitate the occurrence of such events. However, it is difficult to predict cloudbursts as they take place in very small areas which are often devoid of rainfall-measuring instruments.
The consequences of cloudbursts are not confined to small areas. The heavy rainfall events often trigger landslides and flash floods, causing extensive destruction downstream. It is also possible that actual cloudburst events in remote locations aren't recorded.
There are warnings for heavy to very heavy rainfall events, and these are routinely forecast four to five days in advance. The possibility of extremely heavy rainfall, which could result in cloudburst-like situations, is forecast six to 12 hours in advance. However, no meteorological agency can predict the quantum of rainfall and specific cloudburst events.
There are a number of challenges that need to be tackled and prepared for in the wake of cloudbursts. These include:
- Rapid onset and intensity: Cloudbursts can occur very suddenly and with a lot of intensity. This can make it difficult to evacuate people and property in time.
- Flash flooding: Cloudbursts can cause flash flooding, which can sweep away people and property.
- Infrastructure vulnerability: Cloudbursts can damage infrastructure, such as roads, bridges, and buildings.
- Landslides and mudslides: Cloudbursts can trigger landslides and mudslides, which can also be very destructive.
- Communication disruptions: Cloudbursts can disrupt communication, making it difficult to coordinate relief efforts.
- Humanitarian impact: Cloudbursts can cause loss of life, injuries, and displacement.
- Environmental degradation: Cloudbursts can damage the environment, such as by causing soil erosion and flooding.
- Limited forecasting and prediction: Cloudbursts are difficult to predict, which makes it difficult to prepare for them.
The path ahead to mitigate the impact of cloudbursts includes:
- Improvement of drainage infrastructure: This can help to reduce the risk of flooding.
- Improvement of early warning systems: This can help people to evacuate in time.
- Adequate and sustainable urban planning and land use: This can help to reduce the risk of landslides and mudslides.
- Climate change adaptation: This can help to reduce the risk of extreme weather events, such as cloudbursts.
- Public awareness and education: This can help people to understand the risks of cloudbursts and how to prepare for them.
- Infrastructure upgrades: This can help to make infrastructure more resilient to the effects of cloudbursts.
- Emergency response preparedness: This can help to ensure that relief efforts are effective in the event of a cloudburst.
- Research and innovation: This can help to improve our understanding of cloudbursts and develop better ways to predict and mitigate their effects.
The recent cloudburst events in Himachal Pradesh are a reminder of the need to be prepared for these devastating events. By taking steps to improve our forecasting and warning systems, and by investing in infrastructure that can withstand heavy rainfall, we can help to reduce the loss of life and property caused by cloudbursts.