Cloudburst in Himachal Pradesh

It is an extremely high amount of precipitation in a short span of time.
It is a localised but intense rainfall activity that can cause widespread destruction, especially in hilly regions.
Region- It usually occurs over a small geographical region (20-30 sq.km).
Criteria– Rainfall of 10 cm or more in an hour over a roughly 10 km x 10-km area is classified as a cloudburst event.
By this definition, 5 cm of rainfall in a half-hour period over the same area would also be categorized as a cloudburst.
Mechanism- It happens when saturated clouds are unable to produce rain because of the upward movement of very warm current of air.
Cloud formation– This updraft movement of warm wind along with clouds forms the Cumulonimbus clouds.
It can grow up to 12-15 km in height through the entire troposphere (occasionally up to 21 km) and can hold huge amounts of water
Instead of dropping down, raindrops get bigger in size and get pushed up due to the air current.
Eventually they become too heavy to hold and drop down, leading to more rain than usual.

What are the causes of cloudburst?

Monsoon- It often occurs during monsoon season when the South West Monsoon winds bring in large amount of moisture which fuels the cloudburst.
Orographic lift- It is affected by factors like local topology, wind systems, and temperature gradients between the lower and upper atmosphere.
Thunderstorm- It is caused due to excessive amount of condensation in the cloud during thunderstorm.
Climate change– Global warming is leading to more evaporation of water and because of this dense cumulonimbus clouds are forming, resulting in intense rainfall.
- Even 1 degree Celsius rise in global temperature can cause change in monsoon extremes and frequent cloudburst.

What are the areas prone to cloudburst?

Regions more prone:-
- The Himalayas
- Western Ghats
- Northeastern hill States of India
- Coastal regions
Landslides- The heavy spells of rain on the fragile steep slopes trigger landslides, debris flows, and flash floods, causing large-scale destruction and loss of people and property.
Coastal cities- They are particularly vulnerable to cloudbursts since the flash floods make the conventional stormwater and flood management policies in these cities dysfunctional.
- Example- Chennai Floods 2015.

How the administration is responding?

In light of the water overflow due to gate malfunction of the Malana Dam, the Kullu district administration had on Monday urged the locals living on the banks of the Parvati river to stay vigilant.

“We have alerted the people living in villages on the banks of the river that they would be evacuated in case of a breach in Malana Dam 2,” Deputy Commissioner, Kullu, Ashutosh Garg told PTI.

So far, the situation is not serious as only 30 cusec water is overflowing and the Malana Dam 1 below the stream can hold water for some time in case of a breach, allowing evacuation, he said.

The local Meteorological Office had issued an orange alert for heavy to very heavy rains at isolated places in eight of the 12 districts of the state on July 26 and 27 and cautioned against landslides, flash floods, mudslides and increased runoff in rivers.

What are the challenges associated in detecting cloudbursts?

Forecast – Specific cloudburst events cannot be forecast.
Possibility of extremely heavy rainfall, which could result in cloudburst kind of situations, are forecast six to 12 hours in advance.
Failure of satellite- They fail to detect cloudburst systems as the precipitation radars are much smaller than the areas of individual cloudburst events.
High cost– Radars need to installed in wide areas for a wider coverage. Installing radars is expensive.
Technological hurdle– It is difficult for any metrological agency to predict exactly how much rain is likely to fall at any given place.
Although it is difficult to forecast cloudbursts, doppler radars can be helpful in predicting them.
Lack of feasibility – It requires a very dense network of weather instruments, and computing capabilities that seems unfeasible with current technologies

What lies ahead?

Multiple Doppler weather radars can monitor moving cloud droplets and help to provide forecast for the next 3 hours.
Proper community sensitisation regarding the causes, effects and safety precautions of cloudbursts is the need of the hour.

Read also:- What is a Flash Flood?

Cloud Burst in Himachal Pradesh,Cloud Burst in Himachal Pradesh