Tuesday, Nov 29, 2022

How 131.6 mm of rain brought Bengaluru to a halt

As Bengaluru grew, too big and too soon, the lakes and the storm water drains that linked them got choked or encroached upon. As the unprecedented rains and waterlogging of the last few days brought the city to a halt, experts say it's time to set the clock back.

Municipal workers remove blocks and other obstructions to clear the waterlogged Outer Ring Road after heavy monsoon rains, in Bellandur, Bengaluru, September 7, 2022. (PTI)

Among the many striking images to have come out of Bengaluru over the last few days was of Vinod Kaushik, founder-CEO of a construction start-up, getting on to a open truck with his family and pet dogs as they were evacuated from their home in DivyaSree 77 East, an upscale locality in Mahadevapura, in the eastern part of the rain-lashed and waterlogged city.

Merely five km away, in a slum in Munekolalu, Nagesh Nayak had to rush out of his shanty as the rain water gushed in. “At night, the water started entering our house. My family and I, and our neighbours, somehow managed to get out. Our clothes and food were washed away. We were worried for our children as we dragged them through waist-deep water. There was also the fear of snakes,” he said.

His neighbour Lakshmi, a civic worker, said, “The last two days have been terrible here in Munekolalu. The government is only worried about evacuating the rich. Some activists and local people gave us food and water. I carried my children on my shoulders.”

People use Coracle boats to move through a water-logged neighbourhood following torrential rains in Bengaluru, September 7, 2022. (REUTERS)

In a city that grew too big, too soon, the unprecedented rains played the leveller, submerging areas such as upscale gated colonies on and off the Yemalur Main Road to slum colonies such as the one in Munekolalu. In a span of seven days, Bengaluru was marooned twice, bringing the city to a standstill, with the 131.6 mm of rainfall that the city received on September 5 the highest since the 132.3 mm of rainfall on September 26, 2014.

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While the worst-affected areas were Rainbow Drive Layout in Sarjapur, Outer Ring Road, Koramangala, Varthur, K R Puram, several other areas such as Bilekahalli, Madiwala Lake Road, Silk Board Junction, R R Nagar, Nandini Layout, Hebbal, Hennur, Kengeri, Sanjaynagar and Banaswadi also complained of flooding.

A man speaks on his mobile phone as he wades through a water-logged road in a residential area following torrential rains in Bengaluru, September 7, 2022. (REUTERS)

A resident of Rainbow Drive Layout, Darshana Minnoor, said, “Rain water from the surrounding villages of Junnasandra and Halanayakanahalli gets diverted to our layout, from where it is supposed to exit through the storm water drain on Sarjapur Road. Due to difference in levels between our drain and the one on Sarjapur Road, the egress is extremely slow and water stagnates for hours. So any overnight rain causes flooding and water enters our homes.”


Mahadevapura MLA Aravind Limbavalli, whose constituency is part of the Bangalore Central Lok Sabha constituency, had in May announced that the Major Roads department of the Bruhat Bengaluru Mahanagara Palike (BBMP) would construct a drain to carry rain water from the layout to the Sarjapur culvert. However, work is still underway.

According to BBMP chief commissioner Tushar Giri Nath, over 700 houses in Mahadevapura zone and 687 houses in the East zone of the city were flooded. Around 9,500 houses across the city were damaged in the rains.

In a span of seven days, Bengaluru was marooned twice, bringing the city to a standstill, with the 131.6 mm of rainfall that the city received on September 5 the highest since the 132.3 mm of rainfall on September 26, 2014. (Express photo by Jithendra M)

The problem: Encroached drains, unauthorised construction


Environmentalists and urban experts agree that while the heavy rains of the past few days did contribute to the collapse of Bengaluru’s urban infrastructure, the city has come to a standstill with far less. They pointed out that even on August 2, when the city recorded just 45.7 mm rainfall, houses in Yelahanka, Sarjapura and others were affected.

Raj Bhagat, senior programme manager (geo-analytics) at World Resources Institute, India, explained, “The city’s topography is characterised by a series of valleys which radiate from a ridge and fall gradually in all directions. The four major valleys are Vrishabhavathi valley, Koramangala valley, Challaghatta valley and Hebbal valley. The lakes were built across these valleys and floodwater used to flow through these valleys. But with these valleys encroached, the flow of rainwater is impeded. With every road and plot acting as dams/blocks, surface water flow has been severely affected, causing flooding and stagnation in these areas.

Amid heavy rains in Bengaluru, people take part in Ganesh procession and immersion at Ulsoor lake. (Express photo by Jithendra M)

In 2015, the Koliwad Committee, constituted by the state government to look into encroachment of lakes, stated that prominent real-estate developers and government bodies were major encroachers of lakes in Bengaluru. According to the report, about 10,787 acres of lake land worth Rs 1.5 lakh crore had been encroached upon.

Dr T V Ramachandra, faculty at the Centre for Ecological Sciences, Indian Institute of Science (IISc), said, “Poor drainage system, drains clogged with solid waste and building demolition waste, drains that have been encroached upon, unscientific remodeling which includes narrowing and concretisation of drains, loss of interconnectivity among lakes and encroachment of buffer zones (lakes, drains) are some of the reasons behind the flooding. The narrowing of the storm water drains affects their hydrological function. If the drains are concretised, the velocity of water increases, which further enhances the chance of flooding in the area.”

Blaming an “unholy nexus” of contractors, engineers, consultants and local decision makers, Ramachandra said, “In 1800, Bengaluru had 1,452 water bodies with a storage capacity of 35 TMC. These helped in harvesting rainwater and also mitigated flooding. Today, we are left with 193 lakes and most of them have lost connectivity due to blocked storm water drains or encroachment.”

BBMP workers carry out desilting of drains.

Since September 1, the BBMP has identified 175 encroachments on storm water drains in Mahadevapura zone and 126 in Dasarahalli zone.

In a letter submitted to Chief Minister Basavaraj Bommai on September 1, the Outer Ring Road Companies Associations (ORRCA), which represents IT and banking firms in the area, estimated a collective loss of Rs 225 crore due to the flooding following the August 30 rains.


On September 5, the association issued an advisory asking its members to work from home (WFH) for the next five days.

The way out: Back to the basics


“More culverts and new drains are required for water to move along these valley sections. Existing drains require widening wherever possible. Unless we add more drains which allow water to flow through the valleys, every time it rains heavily, there will be floods,” said Bhagat of World Resources Institute.

The Wipro office at Sarjupura Road.

BBMP commissioner Nath said the civic body has issued notices to several property owners who have encroached the drains. “Demolitions of the encroached properties started last week. Moreover, a new drain is being constructed at Outer Ring Road near Ecospace to reduce stagnation of water and the work will be completed soon.. The desilting of drains is an ongoing process,” he said.

While citizens groups have over the years made several representations to successive governments over the years, little has changed.

People being evacuated from the inundated Sunny Brooks Villa in Sarjapura Road.

Urban expert Ashwin Mahesh said, “The government always promised that it would revive the lakes. They even assured the courts that they would do it quickly. Not all lakes are overflowing. Where local people have spent time thinking about inflows and outflows, and worked to fix recurring problems, those lakes are relatively okay.”

Ram Prasad, co-founder of Friends of Lakes, a citizens’ collective, said that the government should start treating lakes and recharge wells as flood mitigation zones. “We have been harping on constructing recharge wells and open wells. These wells help control urban flooding. The detailed project report should be prepared in consultation with the hydrologists and only after the approval of Karnataka Tank Conservation and Development Authority (KTCDA) should the rejuvenation of lakes be taken up,” he said.

Chief Minister Basavaraj Bommai inspects rain-hit Rainbow drive and Yamalur areas.

In several instances, citizen groups have stepped in after several failed representations to the government. For instance, with Anekal taluk in Bengaluru Urban getting flooded every rains, two citizen groups have brought together Bangalore University, an NGO and the Minor Irrigation department to restore linkages between 11 lakes in the region.

“The drains that are connected to the lakes have, at certain points, been encroached upon or are buried under the ground and have thus been rendered defunct. We will work to clear 15 km of storm water drains starting from Anekal Doddakere lake to Bidaraguppe lake on the Tamil Nadu border,” he said.

Workers clean the BESCOM Kadubeesanahalli 66/11 KV sub-station that was inundated due to heavy downpour.

In its 2021 report on storm water drains (SWD) in Bengaluru, the Comptroller and Auditor General had said, “BBMP failed to prepare a SWD manual specifying the design, construction and maintenance of the SWD infrastructure of the city. It failed to factor in reasons for high intensity rainfall due to rapid urbanisation and did not adhere to the provisions of Indian Road Congress and the guidelines of National Disaster Management Authority while designing and constructing roads/drains… Water bodies and drains were not inter-connected and linkage between different drains was absent. This affected free flow of stormwater leading to frequent flooding in various parts of the city.”

Meanwhile, the IMD’s prediction offers little respite. On Wednesday, the forecast said Bengaluru will receive light to moderate rain till September 9.

First published on: 07-09-2022 at 07:59:09 pm
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