CLIMATE CHANGE . Deluge of unlearned lessons

The last time Anuradha Mothali, children’s writer and long-time Hyderabad resident, saw rain this severe was in 2000. Mothali, then a postgraduate student, had watched in horror as incessant rainfall brought parts of the 2,500-acre campus of the University of Hyderabad under water and threatened to cut it off from the rest of the city. She recalls how an embankment of the Peacock Lake on the campus had caved in, creating a mini waterfall of sorts. Some 24 hours later, the lake had all but drained out.

As rain drummed down yet again over Hyderabad on the evening of October 13, Mothali — watching the downpour from her 12th-floor apartment in Gachibowli — couldn’t help but think of the flooded campus. The university is not far from where she lives now, but the locality has changed beyond recognition in recent years.

“All that we had on the 12-km stretch from the campus to Mehdipatnam, the nearby town, were some public sector institutions — mostly government offices or training centres,” Mothali recalls. The rest of the landscape consisted of wooded patches and hillocks with boulders.

Mothali was taken aback when she moved to Gachibowli — now the city’s IT hub — six years ago and found the area thick with multi-storey residential complexes. “We have three lakes in the vicinity and condominiums have come up along two of those,” she says.

This time, again, the writer witnessed the havoc wreaked by the rainfall. All it took was a night of heavy rain for the lakes to fill up; large pits dug up for new construction work also overflowed. Before long, the basements of many high-rise complexes in Gachibowli were flooded.

“When water gets into the basements, there is no alternative but to pump it out; also there are hardly any stormwater drains. Along Gachibowli, one could see hundreds of cars parked on the road as water was pumped out of basements. Images shared on social media had people finding aquatic snakes and fish in the floodwaters of the basement,” she says.

About a fortnight ago, as depression over the Bay of Bengal intensified and made landfall, Telangana and parts of Andhra Pradesh experienced heavy rain. Hyderabad, for instance, was left reeling under one of the worst floods in recent history. Fifty people were killed, and there was widespread damage to crops and property.

If an area receives over 204.5 mm rainfall over 24 hours, the Indian Meteorological Department (IMD) classifies it as an extreme rainfall event. The Begumpet observatory at Hyderabad recorded 210 mm rain in the 24-hour span between October 13 and 14. IMD rainfall data since 1901, compiled by RK Jenamani, senior scientist, national weather forecasting, IMD-Delhi, show that the only time Begumpet recorded a higher rainfall was in 2000, when it received a record 241.5 mm. Parts of the Greater Hyderabad Municipal Corporation such as Hayathnagar recorded 290 mm of rain this October, the heaviest for the locality in the last three decades. The Singapur Town region recorded 320 mm rainfall.

It pours

Extreme rainfall events are now common in large parts of India, and climate scientists have recorded their increasing frequency over the years. Metropolises such as Mumbai, Kolkata and Chennai have witnessed instances of extreme rainfall and flooding in the past five years. And now, with Hyderabad under water, residents and environmentalists wonder why the country’s big cities are not factoring climate change into urban development plans.

The Assessment of Climate Change , a report brought out by the Ministry of Earth Sciences in June, highlights the increase in extreme rainfall events across the country. Though the summer monsoon rain over India declined by six per cent from 1951 to 2015, the report points out that “the frequency of localized heavy precipitation occurrences” has increased worldwide.

“Over central India, the frequency of daily precipitation extremes with rainfall intensities exceeding 150 mm per day increased by about 75 per cent during 1950–2015,” the report states.

In their research paper published in Nature Communications , an open access scientific journal, in 2017, Roxy Mathew Koll, climate scientist at the Pune-based Indian Institute of Tropical Meteorology, and others pointed to a three-fold rise in extreme rain over central India. Apart from the various scientific factors triggering a spike in such events, it also explores the role of a warming Indian Ocean in this phenomenon.

“The moisture in the air is coming from the Indian Ocean, and the oceans have grown warmer. Compared to mainland India, the temperature rise over the Indian Ocean has been greater — up to 1.2 degree Celsius — which is high compared to the global average,” Koll says. He points out that the Indian Ocean also controls the monsoon winds and the ways in which monsoon rain manifests over land. “And the oceans have changed; the temperatures have increased,” observes Koll.

Climate scientists have also been analysing instances of extreme rainfall in the country over the past few years. OP Sreejith, scientist at the Climate Research and Services in IMD Pune, has compiled instances of extreme rainfall events since 2017. His data show that the year 2019 witnessed 554 such events between June and September. While there were 261 extreme rainfall events in 2017, it rose to 321 the subsequent year. After the high of 2019, the country experienced 341 events of extreme rainfall this monsoon season. Most of these events occurred along the western coast, according to the data collected from 3,680 rain gauge stations across the country.

“Compared to the western coast, Central India is climatologically less prone to such events. But a few stations in the region have also recorded instances of extreme rainfall events,” Sreejith stresses. Also, the country has received above-normal monsoon rainfall for two consecutive years now.

Writing on the wall

Even as climate research and analysis establish the frequency and even the rise in extreme rainfall events over the years, deluges continue to throw life out of gear in big cities. BV Subba Rao, Hyderabad-based water expert, rues policy makers’ and administrators’ continuing reluctance to integrate flood-resilient features into urban infrastructure.

The writing on the wall has been clear for two decades now — ever since Hyderabad was inundated in 2000, he says. “We had another flooding in 2005 when it rained heavily for a mere 20-25 minutes and the city came to a standstill. The year 2016 was bad too,” points out Rao, former advisor to the Centre for Climate Change at the Engineering Staff College of India in Hyderabad.

Forecasting systems have become dynamic over the years and weather predictions have improved vastly. Rao points out that Hyderabad had already received over 25 per cent excess rainfall this monsoon, forecasts were in place and so were disaster management bodies. “Then why are our cities not rain-ready? Humans are known for climate adaptation. Why aren’t we now?” he asks.

Rain harvest: The Himayat Sagar lake in Hyderabad was conceptualised as a flood control structure following the 1908 deluge

Lessons in adapting to changing climatic conditions are nestled in history, Rao points out. Hyderabad, like many other major cities in the country, is a historical one. When the Musi River flooded the city in 1908, the erstwhile rulers responded with ways to tackle it: Drinking water sources Osman Sagar and Himayat Sagar lakes were created as flood control structures.

For the future: The Osman Sagar lake was created as a flood control structure

“Hyderabad has historically had one of the best flood mitigation water infrastructures,” Rao observes. Its intricate network of man-made lakes, flood diversion channels such as the Firangi Naala, and flood regulating structures along the Musi had kept the city from inundation. Rapid urbanisation and unscientific urban planning, he rues, have more often than not been at the cost of these extensive systems of floodwater management.

Lakes, he adds, were the city’s system of flood regulation. “Traditional systems that had worked for over 400 years were destroyed in the last few decades. The Firangi Naala took out surplus water from the river. That has been destroyed and now the Old City has been inundated. There were 17 flood regulating structures along 100 km of the Musi. A century ago, floods happened along the river, now the whole city is affected,” he points out.

But how can an ever-expanding city be flood-ready? The keys are all out there, he says, and history is a big part of it. “Urban planning has to integrate the existing water infrastructure. We don’t destroy them.”

He suggests restoring the lakes that aided flood regulation, and enhancing their capacity, considering the instances of extreme rainfall. Illegal structures that interfere with the water network need to be cleared, he adds. Recalibrate strategy and restore existing systems, Rao suggests.

Civilisations have been wiped out by intensive flooding, he warns. Urban civilisation may do well to heed the warning.

P Anima

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