Climate Change

How climate change has increased flood events in India

Rise in temperatures would increase flood events in frequency during end of century (2071-2100), says a climate report

By DTE Staff
Published: Tuesday 16 July 2019
A view of Kerala floods in 2018. Photo: Rejimon Kuttappan__

Climate change has had extreme impacts in India. Rise in average global temperatures have led to a worrying trend of no rain for long periods and then a sudden bout of excessive rainfall, causing extreme weather events, particularly floods which took lives, destroyed homes and agricultural yields as well as resulted in huge revenue losses.  

Rise in temperatures would increase flood events in frequency during end of century (2071-2100), according to Climate change and India: A 4 X4 assessment a sectoral and regional analysis for 2030s report.

Temperatures in the Himalayan region are projected to rise up to 2.6 degrees Celsius and also increase in intensity by 2-12 per cent by 2030s. This will result in increased flash floods events leading to large scale landslides and loss of agriculture area affecting food security, stated the report.

As a result of the changing climate, monsoon rainfall in 2018 was the sixth-lowest since 1901, according to the India Meteorological Department (IMD). It was also the sixth-warmest year since 1901, when recording started.

Further, monsoons in 2019 have also been recorded as the slowest progressing in at least 12 years, IMD data showed. Till July 7, 2019, IMD recorded a rainfall deficit of 21 per cent, while June recorded the second-lowest rainfall in the past seven years after the 42 per cent deficit in 2014.  

Moreover, 20 states in the country witnessed deficient rainfall, while three were in ‘large deficient’ category from June 1 to July 7 this year.

Deficit rainfall and floods 

Despite the scant rainfall, 1.4 million people have been affected by the floods due to heavy rainfall across the North East in the last week. Incessant rainfall in the past 72 hours has cut areas due to flooding.

According to IMD, there remains a rainfall deficit of 14 per cent. On July 6, when Baksa district in Assam was flooding, the deficit in North East was 38 per cent.

The flood situation, according to a release by IMD, may worsen. Heavy to very heavy showers have been predicted across Assam and Meghalaya in the next 48 hours. Another 2 million have been displaced in Bihar due to rising flood waters, media reported.

Other states experiencing floods include Mizoram, Meghalaya, Tripura. Parts of Maharashtra have been put on high alert, media reported.

Earlier in July, five days of torrential rains led to floods in Mumbai city. From June 20 to June 26, Mumbai had received only 8.4 mm rainfall, a deficit of 95 per cent. But, extreme rainfall in the last week of June caused floods in the city. Similarly in 2018, a deficit in rainfall for an extended period and then intense rainfall caused floods, landslides and flash floods.

Kerala, which experienced floods killing more than 500 people, last year also faced a dormant monsoon before the rains began, which did not stop for almost two weeks.

This has been the worrying trend for the past few years. In 2016, Madhya Pradesh and Rajasthan faced a drought-like situation when floods occurred in July-August, while Bihar and Assam — two states that are facing their worst floods in almost three decades, had deficit rainfall that monsoon.

Global rainfall data for over the last century also shows an alarming trend. The number of rainy days is decreasing while intense rainfall events of 10-15 centimetre per day are increasing. This means that more amount of water is pouring down in lesser time. For example, globally, 50 per cent of annual precipitation (rain, snow and ice) is received in just 11 days.

Widespread extreme rain events over Central India have increased three-fold in the 66-year period between 1950 and 2015, showed a study published in the journal Nature Communications.

A 10-30 per cent increase in rainfall events over the region where more than 150 mm of rain is registered in a day has been occurring despite a general weakening of monsoon circulation, it noted.

Another study conducted by the Indian Institute of Technology, Gandhinagar, had predicted an increase in extreme rainfall events in Southern and Central India and had linked it to global warming due to climate change.

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