In the context of flood vulnerability, Patna in Bihar stands out as one of the most severely affected districts in India, according to a joint recent research by IIT-Delhi and IIT-Roorkee. West Bengal's Murshidabad and Maharashtra's Thane ranks second and third respectively, according to a district-level flood severity index (DFSI) developed by researchers at IIT-Delhi and IIT-Roorkee.
The index takes into account the historical severity of floods based on the number of affected people, the spread and duration of floods.
The researchers said the top 10 districts where flood severity is the highest are: Patna, Murshidabad, Thane, North 24 Parganas (West Bengal), Guntur (Andhra Pradesh), Nagpur (Maharashtra), Gorakhpur (Uttar Pradesh), Ballia (Uttar Pradesh), East Champaran (Bihar), and East Medinipur (West Bengal).
These are followed by Muzaffarnagar (Bihar), Lakhimpur (Assam), Kota (Rajasthan), Aurangabad (Maharashtra), Malda (West Bengal), Rajkot (Gujarat), Prayagraj (Uttar Pradesh), Aurangabad (Bihar), Bahraich (Uttar Pradesh), Ahmedabad (Gujarat), Jalpaiguri (West Bengal), Darjeeling (West Bengal), Dibrugarh (Assam), Azamgarh (Uttar Pradesh), Chamoli (Uttarakhand), West Champaran (Bihar), Amravati (Maharashtra), Medinipur West (West Bengal), and Samastipur (Bihar).
Though Chamoli in Uttarakhand does not face recurrent floods, it appears on this list because of a few isolated highly damaging flood events.
Among the 30 districts facing the highest risk of floods, 17 are in the Ganga basin and three are in the Brahmaputra basin.
Among all the Indian river basins, the Ganga basin has the highest population, and its high flood proneness is worrisome, said the researchers, including Manabendra Saharia, an assistant professor at IIT-Delhi.
Assam experiences the highest number of floods in India, having faced more than 800 flood events over 56 years. The other flood-prone states, in descending order of flood events, include Kerala, Karnataka, Uttar Pradesh, and Maharashtra.
Data from 1967 to 2023 shows that Thiruvananthapuram has experienced more than 231 floods or more than four events per year on average. Five districts -- Thiruvananthapuram, Lakhimpur, Dhemaji, Kamrup, and Nagaon -- have been categorised as "severely flood-prone," having recorded more than 178 floods, or more than three events per year on average.
The researchers said localised intense rainfall events are likely to rise in the future due to climate change, and therefore, more flash floods are expected.
Under the warming climate, the frequency of cyclones will increase, and coastal and nearby inland areas will face more instances of intense rainfall and floods. It is also likely that areas that are not currently flood-prone may begin to see flooding.
