india

Updated: Sep 16, 2019 08:45 IST

The southwest monsoon overcame an arid start to record slightly above-average rainfall in a year that saw the highest number of extreme rainfall events and the most people killed in the season since relevant data started being recorded in 2010, showed an HT analysis a day before the monsoon officially starts retreating on Monday.

Data recorded close to 1,800 extreme rainfall events this monsoon, more than half of which were in August, underlining the expanding impact of climate change in the June-September monsoon, which accounts for 70% of India’s annual rainfall. Two other standout features of the monsoon this year were the bulk of showers shifting to August (it is usually in July) and the withdrawal of the monsoon getting delayed by almost a fortnight.

Between June 1 and September 14, at least 1,422 people were killed because of rains, the highest since data started being compiled by the Union home ministry nine years ago. Last year, the figure stood at 1,379 – of which Kerala alone accounted for 498 deaths.

Ministry data also showed that monsoon-related deaths were more widespread across India than any previous year with highest toll of 317 in Maharashtra, followed by 203 in West Bengal and 200 in Madhya Pradesh.

According to the India Meteorology Department (IMD), which defines 24-hour rainfall of 115mm to 201.4mm as an extreme rainfall event, three distinct extreme rainfall periods were seen this year. The first was July 10 to 15, leading to flooding in eastern Uttar Pradesh and northern Bihar; the second between July 25 and 31, causing floods in Assam; and the third between August 5 and 12, when coastal states such as Maharashtra, Goa, Karnataka and Kerala experienced floods.

Mritunjay Mohapatra, IMD’s director general, said the intensity of low pressure areas (that facilitate rainfall) will be ebbing from Monday, signalling the withdrawal of the monsoon, but its effect will remain for the next five days. “Thereafter, we can expect the withdrawal process of the monsoon to commence,” he said.

Arvind Kumar Srivastava, head of the climate research division at IMD, Pune, said provisional figures for extreme rainfall events in 2019 were two times more than that in 2018 and 2.5 times that in 2017. “Extreme rainfall in the second part of monsoon (after July) was very high resulting in flash floods in many parts of India. Our data shows that such events this year were more than those recorded in the previous years,” said DS Pai, a senior scientist with IMD, Pune.

There were reasons for cheer, too.

The IMD rainfall data till September 15 showed India receivedan average of 84.1 centimetres of rain, which is 4% above normal. A monsoon is deemed normal when rainfall is between 96-104% of 80 centimetres, which is the 50-year average during the season. Rainfall above 110% is considered surplus monsoon. The average is determined by dividing the total quantum of rainfall received across the country by the total number of meteorological stations, which stands at 2,500.

“We are seeing more than good rainfall with excess rainfall in second half of the rainy season primarily due to weakening of El Nino and continued low pressure over Bay of Bengal till Rajasthan,” Pai said. El Nino is caused by a rise in the surface temperature over the Pacific Ocean and hinders the monsoon by slowing down the flow of moisture-laden winds from the cooler oceans towards India.

The monsoon impacts the lives of two-thirds of India’s population that is dependent on farm income and over 40% of cropped areas that do not have access to irrigation. The monsoon also replenishes 81 nationally monitored reservoirs vital for drinking, power and irrigation.

Professor K Mani, an agriculture economist with Tamil Nadu Agriculture University, said the good monsoon this year would improve agriculture production that can boost demand as 64% Indians are directly or indirectly dependant on the agriculture sector. “But higher farm production does not result in better income for farmers as the wholesale prices of the produce normally falls,” he added.

Studies in the past have shown that whenever farm output is robust, rural incomes and spending goes up. Normal rainfall also usually acts as a check on food inflation.

To be sure, the normal monsoon was unevenly spread. States such as Haryana, Delhi and Uttar Pradesh saw rainfall lag by 47%, 37% and 24% respectively, while Rajasthan, Madhya Pradesh and Maharashtra received excess showers by 36%, 34% and 30% respectively. Together, 11 states received excess rainfall, 16 got normal, and nine were deficient.

Although IMD has predicted a near-normal monsoon in April and May this year, some other weather forecasters had said the rains would be below normal. The monsoon stood at 33% deficient by the end of June, and even as late as July 24, it was 19% below normal.

There were two main reasons for the recovery, said scientists.

KG Ramesh, former director general of IMD, said El Nino was neutralised in the latter part of July by an increase in surface temperature over the Indian Ocean and positive phase of the Equatorial Indian Ocean Oscillation (EQUINOO), a phenomena that encouraged cloud formation and rainfall over the western Indian Ocean.

The second reason was the building of several low pressure areas over the Bay of Bengal. Their movement from the Odisha coast to Gujarat and even Rajasthan kept the monsoon trough almost even across central India.

“As a result till mid-September, central India and southern peninsula received a lot of rain with a slight deficiency in northwest India and a larger deficiency in northeast India and Himalayan plains,” he added.

Also, there were two features of the 2019 southwest monsoon that stood out.

One was the bulk of monsoon showers shifting to July from August. In fact, half of the rainfall received during this monsoon was between July 20 and August 25, said SD Attri, deputy director-general of IMD.

The second was the delayed withdrawal of the monsoon, which usually begins on September 1. The IMD said the continued low pressure over Bay of Bengal delayed the retreat, which will begin from Jammu and Kashmir, Rajasthan and some parts of western India from Monday but will continue till the end of month over central and southern India. This means the monsoon will remain active over Kerala and Tamil Nadu till mid-November, a month after the normal date of monsoon retreat from the southern tip of India.

“In the past several years, we have seen that monsoon withdrawal has been delayed and it is another indication of the impact of climate change on the monsoon pattern,” Pai, who heads climate research services division in IMD, Pune, said.

Experts said the 2019 monsoon clearly showed the changing pattern of India’s most crucial weather event. After a delayed onset, slow progress and erratic bouts of rainfall seem to be the new normal. “We have clearly seen that each year, the floods are growing in intensity and rain events are getting more variable and more extreme. All this was clearly evident in 2019,” said Sunita Narain, director general of Delhi-based advocacy group Centre for Science and Environment.

Extreme rainfall events were also discussed at the recently concluded global conference of parties of the United Nations Convention to Combat Desertification (UNCCD). The delegates and experts highlighted how such events can lead to a higher frequency of droughts and impact hydro power generation. The 190 member countries adopted the Delhi Declaration that asked all stakeholders to introduce land-use management plans to deal with extreme weather events, such as extreme rainfall events.