Bengaluru Rains: Why the city witnesses flooding and waterlogging almost every year

The Karnataka State Natural Disaster Monitoring Centre on Tuesday forecast extremely heavy rain, thunderstorms, and lightning on Wednesday, May 21, and heavy rain, thunderstorms, and lightning for May 22 and 23. Heavy rain is also predicted for the following three days, on May 24, 25, and 26.

Which areas of Bengaluru are the worst affected by rains?

Since Sunday, heavy rainfall has wreaked havoc across Bengaluru, with multiple zones reporting significant damage due to flooding.

• Bengaluru Urban received 278 mm of rainfall between May 1 and 20, 157 per cent more than normal, and almost a fifth of the annual normal rainfall for the district.
• In the Yelahanka zone, which recorded 103.2 mm of rainfall, overflowing lakes caused flooding in low-lying areas, damaging 28 homes.
• Kengeri’s Kote Layout received the city’s highest rainfall at 132 mm between Monday and Tuesday. Floodwaters inundated at least 100 houses and damaged over 50 vehicles.
• Koramangala’s ST Bed Layout, a perennial victim of monsoon flooding, saw homes submerged under four feet of water, with at least 21 houses affected.
• In Shanthinagar, the local bus depot was swamped with two feet of water, damaging numerous buses and other vehicles.
• One of the hardest-hit areas was Sai Layout near Mahadevapura, developed by the Bangalore Development Authority (BDA). Floodwaters reached four feet inside homes, prompting authorities to deploy boats to rescue stranded residents.

Why is Bengaluru prone to flooding every year?

The city’s topography may partly explain its flooding woes. Bengaluru is situated on an elevation of about 900 meters and lacks a major river to channel excess water naturally, unlike other metropolitan areas.

In the year 1800, Bengaluru, then a 740 sq km region, had 1,452 water bodies with a water storage capacity of 35 TMC (thousand million cubic feet), allowing for optimal rainwater harvesting and flood mitigation.

Bengaluru also has interconnected lake systems, with over 190 lakes today. The city’s burgeoning expansion has resulted in rampant encroachment of both the lake beds and the interconnecting valley zones, in violation of ecological norms.

Vishwanath S, a water expert and an urban planner, points out that areas like ST Bed Layout and Manyata Tech Park, which are built on lake beds, are organically prone to urban flooding. He also said that the SWD system along Hosur road in Electronic City had gradually ‘disappeared’ due to rapid urbanisation, leading to heavy waterlogging.

Environmentalists and water conservationists have also flagged the poor status of the city’s current drainage system, which they say is outdated and ill-equipped to handle the city’s current population and rainfall intensity. Bengaluru’s rajakaluves (stormwater drains) frequently get blocked with solid waste.

Vishwanath also said that the city’s administrative body, the Bruhat Bengaluru Mahanagara Palike (BBMP), needed to implement a master plan for building new stormwater drainage infrastructure.

“The Rs 5000 crore loan sought by the Karnataka government from the World Bank should be utilised to build a new storm water drain infrastructure,” he told The Indian Express. “BBMP should develop a master plan for SWD, especially in the peripheral area. We cannot depend on the past infrastructure for the current problems. The government needs to prepare a comprehensive plan and listen to local voices.”

How has the government responded?

BBMP Administrator Tushar Giri Nath inspected the flood-affected areas in Bengaluru on Monday, travelling by tractor to assess the situation in Sai Layout and nearby regions. He identified the primary cause of waterlogging in the area as ongoing road-widening work on a railway vent near Geddalahalli, which disrupted the flow of stormwater, exacerbating flooding in the area.

To address the issue, Nath stated that he has issued directives to accelerate the completion of the road-widening project to restore proper drainage and mitigate future flooding in Sai Layout. He added that the BDA is executing the drainage work, but legal action by individuals has delayed its completion.

Deputy Chief Minister and Bengaluru development minister DK Shivakumar on Monday said that the civic agency had identified 210 flood-prone zones and had fixed 70 per cent of them. “We had identified 210 areas as flood-prone in Bengaluru… we have fixed flooding issues in 166 (70%) of those localities. Flood prevention work is currently going on in 24 areas, while work will be taken up soon in the remaining 20 areas. We have built 197 km of stormwater drains,” he said.

“The traffic police have identified 132 spots which are flooded during heavy rains. Of these, we have rectified issues in 82 spots, and 41 spots are yet to be fixed. We are spending Rs 2,000 crore for storm water drains,” he explained.

BBMP has now set up a control room to address the grievances of the citizens.