A recent study, published in the Journal of Hydrometeorology by the American Meteorological Society, reveals that river basins in peninsular India have a greater likelihood of experiencing extensive flooding when compared to the Ganga and Brahmaputra rivers.
Analysis of Widespread Floods
- Researchers examined seven major river basins: Ganga, Brahmaputra, Godavari, Krishna, Mahanadi, Narmada, and Cauvery.
- The analysis covered the period from 1959 to 2020.
Findings
- The study found Mahanadi and Narmada had the most frequent widespread floods with 40 incidents.
- Krishna and Godavari experienced over 20 widespread floods.
- Meanwhile, Ganga, Brahmaputra, and Cauvery had less than 15 such events.
Seasonality And Flood Probability
- A strong seasonal trend was noticeable in widespread flood probability.
- All river basins, except Cauvery, experienced widespread flooding in August, during the summer monsoon season.
Ties To Rainfall
- The seasonality trend is linked with rainfall.
- India gets about 80% of its yearly rainfall from June to September.
- Godavari, Mahanadi, and Narmada, located in the core monsoon region, received more rainy days from July-September.
- During the months of October to December, the river Cauvery experiences flooding due to significant rainfall in its subbasins during the northeast monsoon season.
- During the months of June and July, the Brahmaputra river basin encountered extensive flooding due to the early onset of rainfall in the northeast region, which differs from the timing observed in the northern states of India.
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Causes And Effects Of Widespread Flooding
- The 2018 Kerala floods, the 2022 Pakistan floods, and the lower Mississippi river floods in 2008, 2011, and 2015-19 were linked to atmospheric rivers.
- Atmospheric rivers are vast sections of the Earth’s atmosphere that transport water vapor from the tropics to the extratropics.
- In India, widespread floods correspond with large atmospheric circulations causing precipitation in the river basin.
Climate Change And Flooding
- Climate change is anticipated to alter the timing, frequency, and likelihood of widespread floods, as per the researchers’ findings.
Source: Down To Earth