Why so many cloudbursts? Experts point to rising temperature

Cloud burst is a sudden and intense downpour of rain for a short period of time, over a restricted geographical area (a few kilometers of radius) , which causes mass destruction.It causes flash floods in the area, along with that landslides, house collapse etc are the major consequences to it.

What are the regions prone to it?

Cloudbursts are very common in Himalayan  region. Western ghats and coastal areas also experience occasional cloudbursts.

Why are the hilly areas more prone to cloud burst?

The topographic condition of the hilly areas favors the formation of theses kind of situations. Due to heavy slopes, precipitation during rainfall increases steadily thus giving room to the cumulonimbus cloud to spread and create large heavy cloud resulting in a cloud burst.

Uttrakhand Cloudburst

On June 2, 2019 a cloudburst over Uttarakhand’s Lambagad village in Chamoli district killed one person. Soon after, an alert was issued in the state’s Almora region owing to rising water level in Ramganga River.

While this is the first cloudburst of 2019, the state faced around a dozen of these extreme weather events last year. Experts say not only has the frequency of such events increased, but their timing has also changed.

“The number of cloudbursts is definitely increasing and their time pattern has also changed. We are hardly in June right now and a cloud burst has happened. Earlier, cloudbursts were common during monsoon or post-monsoon period, which is September-October. Cloud bursts are happening sooner every year,” said Kireet Kumar, scientist at GB Pant National Institute of Himalayan Environment and Sustainable Development.    

Kumar added that the main reason for this increase is rising temperatures due to climate change. “Rainfall depends on temperature which impacts wind pattern and cloud formation. With increasing temperatures, such events are on the rise,” he said.

The decadal temperature rise in the Himalayan region is higher than the global rate of rising temperatures. “Several climate change studies over the Himalayas reported a consistent warming in the present climate with rate of warming much higher than the global average of 0.4 degree Celsius. The reported rate of warming over Nepal is 0.6 °C/decade during 1977–2002 and 0.6 °C/100 year during 1901–2002 over the eastern Himalaya," according to a study titled Future changes over the Himalayas: Maximum and minimum temperature published in the journal Elsevier in January 2018

"The Tibetan plateau and Brahmaputra basin showed the largest increase during spring season with 0.2 °C/decade during 1971–2005 over northeast India and warming of 1.6°C across the north-western Himalayan region during 1901–2002,” added the study.

High temperatures result in increased moisture levels, according to Sandipan Mukherjee, another scientist at GB Pant National Institute of Himalayan Environment and Sustainable Development.

He added, “This moisture content then manifests itself in the form of either pre-monsoon thunderstorms in the Indo-Gangetic Plains or cloud bursts or hailstorms in mountainous regions like Uttarakhand.”

However, Mukherjee also said monitoring and observation have issues too that predictions inaccurate. “We do not have the equipment to measure rainfall and that’s why it becomes difficult to say if a particular extreme rainfall event is a cloud burst or not,” he said.

He also talked about the possibility of there being a link between forest fires and extreme rainfall events, although no study has been done so far to establish this correlation.

“Theoretically, it is can be said that forest fires and rainfalls are linked because fires give out a lot of smoke and other particulate matter which can aid rainfall if there is moisture in the air. This is the basic idea behind artificial rainfall. However, no studies have been done in India to test this,” he said.

According to the Uttarakhand Forest Department, 36 big fires were active in Chamoli before the cloudburst.  

Man-made reasons for Uttarakhand disaster

The valleys of the Yamuna, the Ganga and the Alaknanda witness heavy traffic of tourists. For this, the government has to construct new roads and widen the existing ones," says Maharaj Pandit, professor with the Department of Environmental Sciences in Delhi University. He says that a study should be conducted to assess the carrying capacity of the Himalaya and development should be planned accordingly.

Roads destabilising mountains

"A new (mountain) range like the Himalaya will remain steady if not tampered with much. But the huge expansion of roads and transport is bringing the mountains in Uttarakhand down," says Pandit. Road, he says, is a major destabilising factor for a mountain and it is a new phenomenon for the Himalaya.

Pandit, who is in Uttarakhand for a research project, recounts an observation. "I was sitting at the Prayag bridge for tea and started counting the number of buses crossing it. Withing seven to eight minutes, 117 buses crossed," he says.

Data with the Uttarakhand State Transport Department confirms this. In 2005-06, 83,000-odd vehicles were registered in the state. The figure rose to nearly 180,000 in 2012-13. Out of this, proportion of cars, jeeps and taxis, which are the most preferred means of transport for tourists landing in the state, increased the most. In 2005-06, 4,000 such vehicles were registered, which jumped to 40,000 in 2012-13. It is an established fact that there is a straight co-relation between tourism increase and higher incidence of landslides.

Threat from dams

The Ganga in the upper reaches has been an engineer’s playground. The Central Electricity Authority and the Uttarakhand power department have estimated the river’s hydroelectric potential at some 9,000 MW and have planned 70-odd projects on its tributaries. In building these projects the key tributaries would be modified—through diversion to tunnels or reservoirs—to such an extent that 80 per cent of the Bhagirathi and 65 per cent of the Alaknanda could be “affected”. As much as 90 per cent of the other smaller tributaries could be “affected” the same way.

Pandit says that rampant construction, be it of roads, or dams, has led to land use change and the cumulative effect is getting reflected in the extent of damage rains have caused.

Landslides more frequent now

“Our mountains were never so fragile. But these heavy machines plying everyday on the kutcha roads have weakened it, and now we suffer landslides more often,” says Harish Rawat, a BSc student in Uttarakhand’s Bhatwari region that suffered a major landslide in 2010.

Rawat lost his home to the landslide when a major part of the main market and 28 shops were wiped out by the landslide. About 25 other houses were destroyed completely.

Another local resident, Ram Prasad Tomar, a driver by profession in Uttarkashi town, says it is road cutting that has made the mountains so weak. He says the way mountains are cut to make roads has rendered the mountains unstable. “Road contractors, who come from outside, do not understand the mountains. Most of the expressways that are being constructed now are tangled in legal cases. After cutting of mountains, landslides continue for up to four years, and contractors go bankrupt clearing the debris,” he says.

Environment engineer and Ganga crusader, G D Agarwal, says that construction along the Ganga has certainly cost a lot more if one includes the cost of damage to environment. People have completely destroyed the ecology of the mountains. “We see more landslides nowadays because of unplanned development in the hills,” he says.