Mumbai: The southwest monsoon rains in 2019 were the heaviest India witnessed in 25 years, as per a statement by the India Meteorological Department (IMD). Between June and September 2019, rainfall was 110% of its "long-period average" (LPA) of 880 mm, the national average of monsoon rains received in the 50 years leading to 2010.

The 2019 monsoon also saw 560 “extreme rainfall events”, 74% more than the number (321) last year, The Indian Express reported on October 5, 2019. (IMD categorises the intensity of rainfall over 24 hour as follows: Heavy when it is 64.5 mm-124.4 mm; very heavy when it measures 124.4 mm-244.4 mm and extremely heavy when it is more than or equal to 244.5 mm.)

Heavy rainfall and floods claimed 1,685 lives across 14 states in the country during the season, nearly 14 deaths a day, on average. Maharashtra accounted for the most, 22% deaths, according to a situation report of the disaster management division under the Ministry of Home Affairs.

Here are some of the significant highlights of the 2019 southwest monsoon:

  • For the first time since 1931, season rainfall was more than the LPA even though June recorded over 30% deficiency
  • Highest recorded rainfall (115% of LPA) in August 2019 after 23 years
  • Second-highest September rainfall (152% of LPA) after 102 years
  • For the first time since 2010, rainfall from July to September was above the LPA
  • August-September recorded the highest (130%) cumulative rainfall after 36 years
  • During 18 of the last 19 years (2001-2019), the north-east received less than LPA rains with the exception of 2007 (110%). This indicates a below-normal epoch for the region, last seen between early 1950s to mid-1980s, the IMD release said.

The number of extreme rain events over central India tripled between 1950 and 2015, according to a 2017 study led by researchers at the Indian Institute of Tropical Meteorology, Pune. This affected 825 million people, leaving 17 million homeless and killing about 69,000, IndiaSpend reported on September 5, 2019.

A seemingly normal monsoon with new peaks and lows in rainfall is set to be the new norm, we had reported in May 2019, using Rajasthan as an example. Erratic rainfall increases distress migration and particularly impacts the quality of life of women and public health, we had said.

Climate change in several states is an added stressor on agriculture, already stressed by various resource and policy related issues, we had reported in January 2019. In Karnataka’s Kaveri basin for example, erratic rains damaged 25% of the crops sown, we reported on October 3, 2019. Sowing of kharif (summer) crops like paddy, sugarcane, ragi was postponed from June-July, which saw scanty rainfall, to August-end which recorded intense downpours.

Starts deficient, ends in excess

The monsoon in June was almost 30% deficient across the country, it picked up in July and continued in August-September, KS Hosalikar, deputy director-general of meteorology, India Meteorological Department, Mumbai, told IndiaSpend. The performance of monsoon all over the country (in terms of averages) continued to remain more than 100% from mid-August to September-end.

The monsoon was bookended between two cyclones in the Arabian Sea, Hosalikar pointed out. There was the “very severe” cyclonic storm Vayu in June at the start of the monsoon and Hikka close to its withdrawal. Even the Bay of Bengal was very active in the formation of low-pressure systems.

During the first fortnight of August, monsoon in Maharashtra saw some of the “most severe floods” after 2005-06, as per Hosalikar. These covered Kolhapur, Sangli, Satara and some places in Ratnagiri and Sindhudurg. This was due to the low pressure formed in the Bay of Bengal, which “intensified into a deep depression, a notch below the cyclone which again moved in its preferred direction over central India”, he said.

Five extreme rain events in one season in Mumbai

The monsoon, this season, not only brought plenty of heavy rain in the country but also led to huge loss of life and property. Beginning July 2019, Assam and Bihar were flooded, followed by Maharashtra, Kerala, Karnataka, Gujarat, Uttarakhand and Himachal Pradesh. Even in the weeks leading to the withdrawal of monsoon, there were floods in Bihar, Uttar Pradesh, Punjab, Rajasthan and Madhya Pradesh that caused extensive loss to life and property.

Cities like Pune, Patna and Vadodara saw severe flooding. Mumbai experienced heavy rainfall in the first week of July 2019, with some parts receiving the second-highest rainfall in July in 45 years that brought the financial capital to a halt, claiming nearly 16 lives, IndiaSpend reported on July 2, 2019.

“Mumbai had never experienced five extremely heavy rainfall events (200 mm or 20 cm rainfall) in a single season in its history, something very unique that occurred in 2019,” Hosalikar said.

As mentioned above, Maharashtra reported the most deaths--377 or 22% of total fatalities caused by floods and heavy rains. It was followed by West Bengal (225), Kerala (181), Madhya Pradesh (181) and Gujarat (150), official data show. More than 20 million people were affected across 10 states; and 283 districts in 14 states were affected.

Source: Disaster Management Division, Ministry of Home Affairs; Figures as on September 30, 2019. *Average in 22 districts; **(June 8, 2019 to September 30, 2019); ***(June 1, 2019 to September 30, 2019); ****(May 3, 2019 till September 30, 2019). Note: 14 states counted with deaths reported, Delhi did not state/report any death so not counted. Situation report have not been received from 14 states/UTs: Andhra Pradesh, Chhattisgarh, Goa, Jammu and Kashmir, Jharkhand, Haryana, Nagaland, Mizoram, Manipur, Sikkim, Tamil Nadu, Telangana, Dadra & Nagar Haveli and Lakshadweep.

The climate change factor

As many as 6,585 people lost their lives due to rain-related natural calamities--such as cyclones, floods and landslides--in India over three years ending July 18, 2019, according to official data, IndiaSpend reported on July 29, 2019.

Over 64 years, 107,487 people died due to heavy rains and floods across India between 1953 and 2017, according to Central Water Commission data presented to the Rajya Sabha (Parliament’s upper house) on March 19, 2018, we reported on July 17, 2018.

“The main reasons of floods have been assessed as high-intensity rainfall in short duration, poor or inadequate drainage capacity, unplanned reservoir regulation and failure of flood control structures,” according to a reply in Rajya Sabha, the upper house of the Parliament.

“The high-intensity rainfall that we are witnessing (a part of it) is because climate change is influencing our weather patterns,” said Hem Dholakia, senior research associate at Council on Energy, Environment and Water, a New Delhi-based think-tank. “Science has not reached that point yet (of establishing or associating a single event/incident to climate change) but what we can definitely say that climate change influences the frequency and intensity of such extreme events.”

Heavy rainfall events in urban India have become more frequent over the past 100 years; there has been an overall increasing trend of events exceeding 100, 150 and 200 mm since the 1900s, and an increasing variability in recent decades, IndiaSpend reported on August 29, 2017.

It is clear that the increasing rate of intense rainfall events over Mumbai and the Western Ghats is due to rising temperatures, Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology, Pune, had told IndiaSpend.

Poor drainage, rising urban population

Apart from heavy rains, various factors add to the flooding of cities, experts told us. A city that gets over 200 mm rainfall within a span of 4-5 hours can suffer water-logging--as Mumbai did--because it takes time for water to recede, said Hosalikar. The timing of rainfall, tide levels and changing land use format too are factors.

Growing population and urban migration are other challenges, Dholakia said. “There is a growing demand for housing, and some of this is met through reclaiming natural water bodies such as lakes and ponds,” he said. “Natural drainage systems are either removed or blocked for development and construction activities, leading to higher risk of floods.”

A reactive approach to rain-related disasters will be ineffective, said experts. “If you are not going to climate-proof (the infrastructure), then all the investment is going to suffer,” said Dholakia. “The way to do this is to do a risk assessment based on probable future scenarios and then put a plan in place. It could be an early warning system for example.”

While investing in city infrastructure, he pointed out, it is important to factor in the increasing intensity of monsoon rains. Storm-water drainage is one such aspect of urban design. “We typically do not have storm-water drainage for several new constructions,” he said. “We have depended upon natural drainage systems like marshlands. We are now cutting trees. All of this makes the impact of heavy rainfall events exaggerated or aggravated in many ways.”

(Mallapur is a senior analyst with IndiaSpend.)

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