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On Tuesday (August 5), a sudden flash flood caused by a cloudburst in the Kheer Ganga river catchment area swept away houses, shops and roads, leaving a trail of destruction. Two cloudburst incidents were reported, one in Dharali and another in the Sukhi Top area, resulting in widespread destruction. Dharali bore the brunt of the damage. This latest incident adds to a growing list of extreme weather events that have struck the hill state in recent years, particularly during the monsoon.

In this context, knowing about the cloudburst from a broader perspective becomes essential. 

Uttarakhand Uttarkashi Cloudburst: Relief and evacuation efforts are underway across affected areas. (Source: Express Photo)

(Relevance: UPSC Syllabus General Studies-I, II: Geography, Disaster Management. 

In 2022, UPSC has asked a question: Explain the mechanism and occurrence of cloudbursts in the context of the Indian subcontinent. Discuss two recent examples. Questions related to climate events and climate-related reports have been UPSC favourites. In this regard, having a comprehensive understanding of this topic is important from the exam perspective.)

Question 1: What are cloudbursts? Is the frequency of cloudbursts increasing?

A cloudburst is a localised but intense rainfall activity. It is a short-term extreme precipitation that takes place over a small area; it is not, as is sometimes understood, the breaking open of a cloud resulting in the release of huge amounts of water. Cloudbursts have a very specific definition. 

The India Meteorological Department (IMD) defines cloudburst as unexpected precipitation exceeding 100mm (or 10 cm) per hour over a geographical region of approximately 20 to 30 square km. Significant amounts of rainfall such as this can result in floods.

Basically, all instances of cloudbursts involve heavy rain in a short period, but all instances of heavy rain in a short period are not cloudbursts if they do not fit this criterion.

Is the frequency of cloudbursts increasing?

Cloudbursts are classified as an extreme weather event because the frequency of cloudbursts has increased due to global warming across the world. Extreme precipitation events are increasing in frequency as global temperatures rise, a trend that experts think may be contributing to an increase in cloudbursts.

As Amitabh Sinha of The Indian Express explains – “There is a paucity of past data on cloudbursts; in addition, since only some of them get counted – only those that result in death and destruction – there is a problem of accuracy as well. But what is very clear is that events of extreme precipitation have been on the rise in the last few decades due to global warming; it is expected, keeping in mind that trend, that cloudburst events might be on the increase as well.”

Question 2:  Can cloudbursts be forecast?

The India Meteorological Department forecasts rainfall events well in advance, but it does not predict the quantum of rainfall — in fact, no meteorological agency does. The forecasts can be about light, heavy, or very heavy rainfall, but weather scientists do not have the capability to predict exactly how much rain is likely to fall at any given place.

Additionally, the forecasts are for a relatively large geographical area, usually a region, a state, a meteorological sub-division, or at best a district. As they zoom in over smaller areas, the forecasts get more and more uncertain. Theoretically, it is not impossible to forecast rainfall over a very small area as well, but it requires a very dense network of weather instruments, and computing capabilities that seem unfeasible with current technologies.

As a result, specific cloudburst events cannot be forecast. No forecast ever mentions a possibility of a cloudburst. But there are warnings for heavy to very heavy rainfall events, and these are routinely forecast four to five days in advance. Possibility of extremely heavy rainfall, which could result in cloudburst kind of situations, are forecast six to 12 hours in advance.

1. 01
   

   Why does cloudburst, which is only heavy rainfall, cause so many deaths?

   The rainfall itself does not result in the death of people, though sometimes, the raindrops are big enough to hurt people in a sustained downpour. It is the consequences of such heavy rain, especially in the hilly terrain, that causes death and destruction. Landslides, flash floods, houses and establishments getting swept away and cave-ins lead to the deaths.

2. 02
   

   What is the Glacial Lake Outburst Flood (GLOF)?

   GLOFs are disaster events caused by the abrupt discharge of water from glacial lakes — large bodies of water that sit in front of, on top of, or beneath a melting glacier. GLOFs can unleash large volumes of water, sediment, and debris downstream with formidable force and velocity. The floodwaters can submerge valleys, obliterate infrastructure such as roads, bridges, and buildings, and result in significant loss of life and livelihoods.

3. 03
   

   How common are floods?

   According to government data from a project by the Assam State Disaster Management Authority, India is the worst flood-affected country in the world after Bangladesh and accounts for one-fifth of the global death count due to floods.

Question 3: Why do cloudbursts mostly occur in hilly or mountainous areas, and how can they lead to flash floods?

Cloudbursts do happen in plains, but there is a greater probability of them occurring in mountainous zones, mainly because of three main factors: first, the wind pattern; second, the height of the mountains; and third, the level of moisture and humidity in the air.

Cloudbursts are more common in hilly areas because of a phenomenon called ‘orographic lift’, which basically means warm air rising up the side of a mountain. As warm air ‘climbs’ a mountain, it expands because of the low pressure at higher altitudes. The expanding air cools, releasing the moisture it was holding as rain. 

However, in many cases, as more and more warm air keeps rising, it prevents that rain till a large amount of rain builds up and bursts out in a massive shower all at once—resulting in a cloudburst.

In the mountains, the formation of low-pressure areas at the top attracts clouds with significant force, intensifying the buildup. Additionally, when air coming from the opposite direction collides with the mountain, it can result in a heavy downpour. This is why the height of the mountain matters in this scenario. The air cannot penetrate the mountain.

In hilly areas, sometimes saturated clouds ready to condense into rain cannot produce rain due to the upward movement of the very warm current of air. Instead of falling downwards, raindrops are carried upwards by the air current. New drops are formed, and existing raindrops increase in size. After a point, the raindrops become too heavy for the cloud to hold on to, and they fall suddenly and collectively—causing a flash of intense rainfall typical of a cloudburst.

How can cloudbursts lead to flash floods?

“A flash flood is a flood of short duration with a relatively high peak discharge in which the time interval between the observable causative event and the flood is less than four to six hours”.- World Meteorological Organisation (WMO)

According to the study, only 25% of the flash floods that occur in India are directly caused by extreme precipitation. The rest of them are a result of a combination of extreme rainfall and the condition of the soil before precipitation.

Houses partially submerged due to a flash flood triggered by a cloudburst at Dharali, in Uttarkashi district, Uttarakhand, Tuesday, Aug. 5, 2025. (PTI Photo)

In India, flash floods are often associated with cloudbursts. As cloudbursts happen in localised areas and they are difficult to capture accurately, the sudden rain released by a cloudburst can quickly overwhelm drainage systems and lead to flash floods and landslides. 

Frequently, flash floods are accompanied by landslides, which are sudden movements of rock, boulders, earth or debris down a slope. It is common in mountainous terrains, where there are conditions created for it in terms of the soil, rock, geology and slope. Himalayan states further face the challenge of overflowing glacial lakes, formed due to the melting of glaciers, and their numbers have been increasing in the last few years.

Question 4: What should India do to reduce the risk of future catastrophe?

An alarming increase in extreme weather phenomena — sudden cloudbursts, flash floods, and landslides — that threaten lives, livelihoods, and ecosystems presents the accelerated impacts of climate change. In this context, it becomes essential to take the right measures in the right direction to reduce the risk of future catastrophe.

📍As changing climate has destabilised weather patterns, in order to saving lives and reduce damage during natural disasters effective early warning systems are critical. For the same expanding and modernising weather monitoring infrastructure, especially in the Himalayas and fragile mountain regions, is essential. Establishing more Automatic Weather Stations (AWS) and utilising satellite-based observation systems can provide real-time data critical for early warnings.

Anjal Prakash explains it: “AWS and advanced meteorological models can provide real-time data that forecasts extreme weather events well in advance when fed into predictive algorithms. This will allow authorities to issue timely alerts, evacuate vulnerable populations, and mobilise relief efforts before catastrophe strikes. International examples, such as Nepal’s pioneering use of early warning systems for mountain disasters, illustrate how technology can mitigate risks when integrated into a comprehensive disaster preparedness plan.”

📍Integrating ecological solutions into broader infrastructure planning is vital. As Anjal Prakash explains “Instead of relying solely on grey infrastructure (such as dams and embankments), India must embrace ecological solutions — restoring wetlands, mangroves, and natural sponge zones that absorb floodwaters and reduce runoff. These nature-based solutions are cost-effective, sustainable, and adaptable to changing climate conditions.

In the mountains, land-use planning must prioritise the preservation of forests and natural buffers that minimise landslides and stabilise slopes. Reforestation and afforestation programs should be expanded, especially in areas prone to erosion. These measures increase the resilience of local ecosystems and communities, helping them withstand climate change shocks.”

📍Climate change adaptation must be embedded within policy frameworks. This involves mainstreaming climate resilience into urban and rural planning, allocating dedicated funds for climate risk assessments, investing in resilient infrastructure, and empowering local communities with knowledge and resources.

📍Community-based disaster management should also be prioritised, particularly in vulnerable rural and hill areas. As residents of particular areas often possess valuable traditional knowledge about weather patterns and natural warning signs, which can be integrated into official early warning systems for more effective responses.

Furthermore, strengthening climate resilience through collaboration and innovation is the need of the hour. As climate change is a systemic challenge, it requires coordinated action at all local, national, and international levels; thus, investing in research, fostering innovation in climate resilience technologies, and partnering with regional neighbours can bolster adaptive capacity across the Himalayas and beyond.

Post Read Questions

Prelims

(1) Which of the following statements with regard to cloudburst is/are correct? (UPSC CDS 2017)

1. It is defined as sudden localized very heavy downpour with cloud thunder and lightning.

2. It mostly occurs in the hilly areas.

3. It results into very high intensity of rainfall, i.e., 250 mm-300 mm in a couple of hours.

4. It occurs only during the daytime.

Select the correct answer using the code given below.

(a) 1, 2, and 3

(b) 1, 3, and 4

(c) 2 and 3

(d) 2 only

(2) With reference to the glacial lake outburst floods (GLOFs), consider the following statements:

1. These are sudden and catastrophic floods caused by the failure of natural dams, usually formed by glacial moraines or ice.

2. Thawing of permafrost decreases the risk of GLOFs.

3. Melting of glaciers increases the risk of GLOFs.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

(3) With reference to the Cloudbursts, consider the following statements:

1. Cloudbursts are short-lived extreme weather events in which heavy rainfall occurs over very small areas.

2. They are more common in hilly areas because of a phenomenon called ‘orographic lift’.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Mains

Discuss the causes and effects of cloudbursts, and suggest measures to prevent and mitigate their devastating impacts.

(Sources: Uttarkashi Cloudburst News Live Updates, What are cloudbursts, and why they occur more in places like Amarnath, What are flash floods, What are cloudbursts, Why are cloudburst incidents rising across India?, Uttarkashi Cloudburst: What India should do to avoid further climate catastrophe)

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