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Floods Triggered By Atmospheric Rivers

Context

  • An analysis that was recently published in the most recent issue of Communications Earth and Environment journal found that from 1985 to 2020, atmospheric rivers (ARs) were directly responsible for about 70% of India’s major flood events that occurred during the summer monsoon season.
    • Researchers from the University of Washington, the National Institute of Technology, and the Indian Institute of Technology (IIT) Gandhinagar collaborated to conduct the study.

Relevance:

GS Paper-3: Climate Change, Global Warming, Atmospheric river and its effects; Disaster Management; Floods

Mains Question

The Atmospheric River AR is what? Discuss the effects of the atmospheric river on the climate globally as well. (150 Words)


Important Findings:

  • The research team used the high-resolution atmospheric fields from the European Reanalysis Version, observed precipitation from the India Meteorological Department, and a historical flood database from the Dartmouth Flood Observatory of the University of Colorado (USA) to study the effects of ARs formed during the summer monsoon season on flooding in India.
  • More than 3% of India’s total geographic area has experienced flooding during each year of the past ten years, according to data from the Dartmouth Flood Observatory.According to a report by the Asian Development Bank, floods in India caused more than $50 billion in damage between 1990 and 2020.

Key Findings:

  • Between 1985 and 2020, seven of the ten floods with the highest mortality rate were linked to ARs.
    • Severe ARs were to blame for the 2013 Uttarakhand floods, which claimed 6,000 lives, the 2007 floods in South East Asia, including India, which claimed 2000 lives, the 1988 Punjab floods, the 400-life 2018 Kerala floods, the 2006 floods in Gujarat, the 1993 floods in Assam, and the 2004 floods that significantly damaged Eastern India and Bangladesh.
    • These floods cost several billion dollars in damages and forced tens of thousands of people to flee their homes.
  • Because atmospheric rivers can hold more moisture due to the warming climate, there is concern that future floods will be even more destructive.
  • Between 1951 and 2020, 596 significant AR events occurred in India.
  • Out of one-third of the top AR events, 54% occurred in the recent three decades, i.e., between 1991 and 2020, indicating a direct link between severe ARs and rising global temperatures. • The frequency and severity of ARs show an increasing trend in India in recent decades. o More than 95% of these ARs occurred during the summer monsoon season, i.e., between June and September.
    • As the climate continues to warm, daily and subdaily precipitation extremes have risen recently and are likely to continue to rise.
  • The South Asian monsoon system is projected to transport more moisture under a warming climate, which may lead to an increased frequency of ARs making landfall in India. o The report also considered extreme daily precipitation to have occurred when the rainfall for a particular day exceeded 1 mm of rainfall.
  • A rise in Vapour Pressure Deficit (VPD) has caused a significant increase in evaporation from the Indian Ocean in recent decades.
  • As the climate has warmed recently, so have the frequency of ARs and the floods they cause. o VPD is the measurement of pressure needed to turn liquid into vapour.
    • As the Indian Ocean warms more quickly, evaporation may increase significantly, which could cause more severe ARs.
  • In India, the impact of ARs varied greatly.
    • The study discovered that while ARs were more severe in North India in July and August, they were more severe in the lower Indo-Gangetic plains and peninsular India during the summer monsoon.

Atmospheric river

  • An atmospheric river (AR) is a confined passageway or filament of highly concentrated moisture in the atmosphere.
  • Alternatively put, it is a phenomenon in which a stream of water vapour moves through the sky like a river on land.
  • It is also known as a cloud band, moisture plume, water vapour surge, tropical plume, and tropical connection.
    • Since ARs can produce enormous amounts of precipitation in a matter of hours or days, they have an impact on India’s water resources and pose dangerous flood hazards.
  • The precipitation levels of these ARs are more in the Western Ghats and Eastern Ghats regions, causing extreme rain events. o The ARs are narrower and carry more moisture.

Way forward:

  • This is the first time that a study has been done to determine how flooding in India is related to ARs.
    • More research is required to determine how global warming affects ARs.
    • As the climate warms, flooding brought on by AR may only get worse.
  • In order to understand the potential for extreme rain events and subsequent flooding during the summer monsoon season in India, comprehensive monitoring of AR would also be necessary for early warning systems. ARs should be a crucial component of the country’s current flood early warning systems, which can aid in adaptation and mitigation.

Conclusion:

Understanding the role of ARs in the current and projected future climate is crucial for mitigating the flood risks. Floods have devastating effects on the economy and society.


March 2024
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