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Extreme Events and Disaster Preparedness

Published: 5th Apr, 2024


The IMD has issued an orange alert in West Bengal and the northeastern regions anticipating heavy rainfall. There is formation of a cyclonic circulation over northeastern Assam. Additionally, the influx of humid winds from the Bay of Bengal is saturating the northern and northeastern regions of the country with moisture.

1: Dimension-Reason behind the changing rainfall pattern

  • Global warming:Global warming leads to a near-term collapse of the ocean's thermohaline circulation (global ocean circulation pattern). 
  • Due to this collapse of thermohaline circulation, warm surface waters move from the tropics to the North Atlanticand extra-warm water surfaces in the Pacific Ocean surrounding the equator.
  • Thus, Western Europe, some parts of Asia, and many parts of the Americas get warmer than normal, and some parts of Europe get cooler rapidly.
    • El Niño and La Niña are examples of this.
  • This latest deviant trend generates dramatic weather impacts, such as:
    • rapid cooling in some parts of the world
    • greatly diminished rainfall in agricultural and urban areas
  • Shift in global wind pattern:UNESCO and other studies found that changes in rainfall pattern could be attributed to the shifts in global wind pattern. These shifts are due to the changes in the ocean surface temperature.
  • Human activity:Effect of human activity on the surface vegetation is also causing rainfall pattern variation.
  • Deforestation:Widespread deforestation in parts of Africa and Asia is causing scarce rainfall and subsequent drought.
  • Triggered cyclogenesis process: The cyclone hotspot districts - Puri, Chennai, Nellore, North 24 Parganas, Ganjam, Cuttack, East Godavari, and Srikakulum – were concentrated along the eastern coastline. The east coast’s warming regional microclimate, land-use change, and degrading forest have triggered the region's cyclogenesis process.

2: Dimension- Government mechanism for preparedness to reduce the risk during such events

  • The government employs early warning systems, disaster management plans, resilient infrastructure, public awareness campaigns, coordination between agencies, specialized response teams, and community engagement to prepare for and mitigate risks during heavy rain and sudden storms.
  • More specifically, the plans range from national disaster plans to the state and district disaster plans from a DRR purview.
  • Similarly, for climate actions, there is
    • NAPCC (National Action Plan on Climate Change) at the national level
    • SAPCC (State Action Plan on Climate Change) at the state level

Fact Box: IMD’s Colour Alerts

  • When it comes to rainfall alerts, IMD issues four colour codes:
    • Green code denotes less than 64 mm of rain in 24 hours.
    • Yellow alert is issued if the expected rainfall ranges between 64.5 mm and 115. 5 mm.
    • Orange alert is issued when rainfall totals between 115.6 and 204.4 mm in a single day
    • Red alert is issued when rainfall totals exceed 204.5 mm in a 24-hour period.


  • Geography: Discuss the meaning of colour-coded weather warnings for cyclone-prone areas given by the India Meteorological Department. (UPSC 2022)
  • Environment: The frequency of urban floods due to high-intensity rainfall is increasing over the years. Discussing the reason for urban floods, highlight the mechanism for preparedness to reduce the risk during such events. (UPSC 2016)

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