The ‘Flying Rivers’ Causing Devastating Floods in India

Home The ‘Flying Rivers’ Causing Devastating Floods in India

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Aug 5, 2024

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Heavy rains and floods have recently impacted various parts of India, resulting in loss of life and displacing thousands of others.

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While floods are a recurrent issue in South Asia during the monsoon season, climate change has intensified their impact.
Scientists now point to a specific phenomenon known as “atmospheric rivers” or “flying rivers” as a contributing factor.
Atmospheric rivers are relatively under-studied in South Asia compared to other weather systems.

Key Highlights:

A 2023 Study revealed that between 1951 and 2020, 574 atmospheric rivers occurred during the Indian monsoon season. Nearly 80% of the most severe AR caused floods in India over the last two decades.
The Indian Institute of Technology (IIT) and the University of California found that seven out of India’s ten most severe monsoon floods between 1985 and 2020 were associated with atmospheric rivers.
Evaporation from the Indian Ocean has significantly increased, leading to more frequent extreme weather events.

The ‘Flying Rivers’ Causing Devastating Floods in India

Atmospheric Rivers (AR):

These invisible ribbons of water vapour originate in warm oceans, where seawater evaporates.
As they move from the tropics to cooler latitudes, they descend as rain or snow, causing floods and avalanches.
They transport around 90% of the Earth’s mid-latitude water vapour, exceeding even the flow of the Amazon River, the world’s largest river by discharge volume.
On average, it is about 2,000 km long, 500 km wide, and nearly 3 km deep, though some extend over 5,000 km.
They are categorised into five types based on size and strength, similar to hurricanes.
These storms are invisible to the naked eye but can be detected using infrared and microwave frequencies from satellite observations.
As global temperatures rise, these rivers have grown longer, wider, and more intense, increasing the risk of flooding.
While some can alleviate drought conditions, their potential to cause catastrophic flooding and landslides is significant.

Global Context:

Global studies show a 20% increase in atmospheric water vapour since the 1960s. ARs are linked to up to 56% of extreme precipitation in South Asia.
Regional Impact: In Southeast Asia and East Asia, ARs contribute significantly to heavy rainfall events, with up to 80% of such events in eastern China, Korea, and western Japan associated with these systems.

Recent Global Flooding Events:

In April 2023 Catastrophic flooding in Iraq, Iran, Kuwait, and Jordan due to high moisture levels in the atmosphere.
Two months later, Chile experienced 500 mm of rain in three days, leading to floods and infrastructure damage.
A year earlier, parts of Australia faced severe flooding caused by a” rain bomb,” which resulted in fatalities and evacuations.

The ‘Flying Rivers’ Causing Devastating Floods in India

What are the Amazon’s ‘flying rivers’?

Flying rivers are massive areas of water vapour, generated by the rainforest, which flow across the Amazon basin.
This natural phenomenon spans eight countries of Latin America and largely stems from the transpiration of the Amazon and the evaporation of the Atlantic Ocean.
The resulting vapour condenses and falls as rain, which influences weather patterns and is vital for Latin America’s water cycle.
The 400 billion trees estimated to be in the Amazon release 20 billion tonnes of water into the air every day.