Preparing India for Extreme Climate Events: Mapping Hotspots and Response Mechanisms

In India, an average of three extreme flood events occurred every year between 1970 and 2004. This yearly average increased to 11 after 2005.

The year 2005 recorded 18 extreme flood events – the highest among all years between 1970 and 2019 – which affected 69 Indian districts. In comparison, the 16 extreme flood events of 2019 affected 151 districts.

The districts with the highest frequency and intensity of floods in India are Dhemaji, Dibrugarh, Golaghat, Karimganj, Lakhimpur and Sivasagar in Assam; West Godavari in Andhra Pradesh; and Chennai in Tamil Nadu.

The 1990s – the report states – recorded 46 major flood events over 156 districts. The decade witnessed intense cyclonic disturbances due to severe depressions over the Bay of Bengal and Arabian Sea, resulting in an intensification of extreme flood events.

Over the next decade (2000-09), there was a spike in extreme floods and associated events – thunderstorms, cloud burst, landslides and hailstorms – covering nearly 473 districts. After 2000, there was a rise in the frequency of floods in urban areas due to such factors as flawed urban planning, encroaching on wetlands and deforestation.

The frequency of associated flood events in India increased in the decade 2010-19. Hailstorms were rare in the past, yet they have been occurring more often in recent decades. They would usually occur before monsoons, but there has been a surge in hailstorm events up to the late monsoon season in central and south India since 2005.

In the last 125 years, four country-wide droughts have been reported. Droughts in the early 20th century led to food scarcity and famines and caused considerable loss of life and property. Studies suggest that the droughts that occurred between 1870 and 1990 were associated with warm El Niño-Southern Oscillation (ENSO) events. (ENSO is a climate pattern involving changes in the temperatures of waters in the tropical eastern Pacific Ocean, affecting rainfall distribution in the tropics.) Recently, droughts have been triggered by land-use changes, ‘urban heat island’ effects and changes in precipitation levels.

A cyclone is a tropical storm originating over tropical or subtropical waters. Before 2005, an average of eight Indian districts were affected by cyclones annually. This number rose to 28 after 2005. The frequency and intensity of cyclonic storms increased in the decade 2010–19, where 58 severe cyclonic storm events affected 258 districts. The most affected districts of the decade included Imphal East in Manipur, Deoghar in Jharkhand, Cuttack in Odisha, and North 24 Parganas in West Bengal. 

According to data from the National Disaster Management Authority, 12 per cent of India’s total land area is exposed to floods and 68 percent is at the risk of drought. Nearly 80 per cent of India’s coastline is susceptible to cyclones and tsunamis. Heatwaves, cold waves, extreme rainfall, landslides, and avalanches are becoming more regular in the country.

In India, the number of districts that have recorded a shifting trend from floods to droughts is higher than that of districts that have shifted from droughts to floods. South India is experiencing an increasing shift towards drought in states like Andhra Pradesh, Karnataka and Tamil Nadu. Western and some parts of Central India are growingly experiencing a drought or drought-like conditions.

Focus and Factoids by Sayani Rakshit.