Why in the News?

• After heavy rains in Himachal Pradesh, landslides occurred, resulting in 22 fatalities.
• Chief Minister Sukhvinder Singh Sukhu reported cloudbursts and advised against approaching waterbodies and vulnerable areas.
• The Indian Meteorological Department (IMD) forecasted scattered to widespread rains in Himachal Pradesh on August 14 and 15, and in Uttarakhand from August 14 to 18, followed by a substantial decrease.

Reasons Behind Intense Rains in Himachal and Uttarakhand:

• The combination of the monsoon trough's northward progression and its interaction with a weakened western disturbance is triggering heavy rainfall in Himachal Pradesh and Uttarakhand.
• The monsoon trough takes the form of an extended low-pressure region, stretching from a "heat low" situated over Pakistan's seas to the Bay of Bengal region's head (encompassing parts of Odisha, West Bengal, and Bangladesh).
• The monsoon trough is a semi-permanent component of the monsoon's circulation, as outlined by the India Meteorological Department.
• Presently, the monsoon trough has shifted northward beyond its usual position, overlaying the foothills of the Himalayas.
• In the near term, the monsoon trough will undergo a southward shift, leading to a temporary decrease in hill-region rainfall and an upsurge in rainfall across the east-central regions of India.

About Cloudbursts

• Cloudbursts refer to highly concentrated and intense rainfall events.
• As per the India Meteorological Department (IMD), cloudbursts involve exceptionally heavy rain concentrated over a limited region, with a rapid rate of around 10 cm per hour.
• This phenomenon is accompanied by robust winds and lightning, typically occurring across an area of about 20 to 30 square kilometers.
• Following this criterion, even 5 cm of rain within just thirty minutes across the same area would be classified as a cloudburst.
• Cloudbursts are relatively frequent occurrences, especially in the monsoon season.
• A majority of these incidents take place in the Himalayan states, where the unique local geography, wind patterns, and temperature differences between various atmospheric layers create favorable conditions for their formation.

Occurrence of Cloudburst:

• Cloudbursts unfold when moisture-laden air ascends hilly terrain, forming vertical cloud columns known as 'cumulonimbus' clouds.
• These clouds typically yield rain, thunder, and lightning. This upward cloud movement is termed an orographic lift.
• Such unstable clouds generate an intense rainstorm over a limited area once they amass enough moisture while being trapped within the ridges and valleys amid hills.
• The energy needed for a cloudburst originates from the ascending air movement.
• Cloudbursts are predominantly witnessed at altitudes ranging from 1,000 to 2,500 meters above sea level.
• Moisture is often sourced from low-pressure systems (associated with cyclonic storms in the ocean) positioned over the Gangetic plains, coupled with low-level winds blowing in from the east.
• On occasions, north-western winds also contribute to cloudburst occurrence.
• Given the multifaceted factors that must align for a cloudburst event, their likelihood is quite rare.

Cloudburst Prediction:

• The India Meteorological Department (IMD) anticipates forthcoming rainfall occurrences with a certain lead time. However, they do not project the precise volume of rainfall—this remains true for meteorological bodies worldwide.
• Forecasts generally pertain to categories like light, heavy, or very heavy rainfall, omitting the exact measurements of rainfall at specific locations.
• Moreover, these predictions encompass relatively larger geographic regions such as states, meteorological sub-divisions, or even districts, and their accuracy diminishes for smaller areas.
• While it's theoretically conceivable to forecast rain for minute areas, the prerequisites include an intricate network of weather instruments and computational capabilities that currently appear impractical with available technologies.
• As a result, the exact anticipation of individual cloudburst incidents remains beyond current forecasting capabilities.

Are Cloudburst Incidents on the Rise?

• There is no discernible long-term trend indicating an increase in cloudbursts, as defined by the IMD.
• Nevertheless, occurrences of extreme rainfall, along with other extreme weather phenomena, are on the rise globally, not solely in India.
• While the total rainfall volume in India has not undergone significant change, a growing portion of precipitation is concentrated within a brief timeframe.
• This implies that instances of heavy rainfall are becoming more intense, accompanied by prolonged dry periods within the rainy season.
• This distinctive pattern, attributed to climate change, potentially signifies an elevated probability of cloudburst events as well.

Consequences of Cloudbursts:

• Flash Floods: Cloudbursts can lead to catastrophic flash floods, resulting in the uprooting of trees and the displacement of boulders and debris.
• Infrastructure Deterioration: The sheer intensity of cloudburst downpours can inflict significant harm on infrastructure, including houses, roads, and bridges.
• Landslides: In hilly and mountainous regions, cloudburst-induced heavy rainfall can precipitate landslides.
• Ecological Impact: Cloudbursts can also negatively impact trees, plants, and crops, causing loss of cultivable land and affecting livestock.

Cloudbursts can trigger a chain of devastating outcomes, encompassing flash floods, damage to infrastructure, landslides, and ecological disruption.

Areas Prone to Cloudbursts in India:

• Cloudbursts primarily occur across the challenging landscapes of the Himalayas, the Western Ghats, and the northeastern hill states of India.
• Intense rainfall on these vulnerable steep slopes triggers landslides, flash floods, and debris flows, leading to extensive devastation and loss of lives and property.
• An illustration of this was the flash floods in the Lidder Valley on July 8, 2022, along the route to the Amarnath Temple in Jammu and Kashmir, which tragically claimed the lives of numerous pilgrims.
• Furthermore, robust monsoon winds along the coastline can also induce cloudbursts, as evident in incidents like Mumbai (2005) and Chennai (2015).
• Coastal cities face heightened vulnerability due to cloudbursts, as these sudden floods can disrupt conventional stormwater and flood management strategies in these urban areas.

Strategies to Mitigate Cloudburst Impact:

• Controlled Construction Near Water Bodies: Regulate construction near riverbanks, considering water levels during heavy rainfall to prevent vulnerability.
• Enhanced Water Control Infrastructure: Reinforce embankments, barrages, and dams to manage and regulate water flow more effectively.
• Ecologically Informed Local Planning: Implement localized planning that acknowledges the region's ecological sensitivity and engages local communities.
• Balanced Infrastructure Development: Scrutinize infrastructure projects and protect eco-sensitive zones to maintain environmental integrity.
• Advanced Forecasting and Technology: Improve IMD forecasting and integrate advanced technology to monitor and predict extreme weather occurrences. This allows for early warnings, evacuation planning, and readiness.
• Eco-Friendly Approaches: Promote eco-sensitive tourism and adopt environmentally friendly policies to foster sustainable development in the area.
• Disaster Management Integration: Embed disaster management and prevention measures into the developmental planning process for a comprehensive approach.
• Addressing Himalayan Region: Address the increasing frequency of cloudbursts in the Himalayan region, driven by the higher decadal temperature rise compared to the global trend.

By implementing these measures, it's possible to alleviate the impacts of cloudbursts and enhance the region's resilience to extreme weather events.

The global incidence and severity of cloudbursts are anticipated to rise due to climate change. A mere 1-degree Celsius temperature elevation could correspond to a 7-10% augmentation in moisture and rainfall levels. This heightened moisture capacity in the air leads to elongated dry spells punctuated by brief bursts of intense rainfall. Consequently, more substantial cumulonimbus clouds form, heightening the likelihood of cloudbursts.

In light of this, immediate actions and well-devised policies are imperative to safeguard lives and assets from escalating extreme events, which are poised to intensify as global temperature shifts intensify.

Mains Question:

• Elaborate on the causative factors and ramifications associated with cloudbursts, and subsequently, examine the strategies aimed at averting and mitigating the profound consequences of these intense rainfall events. (15M)