'Growing Up Pangs': Expert Explains What Caused Bengaluru Floods
S Vishwanath, civil engineer and urban planner, said better storage networks, solid waste management networks and transport networks were needed to resolve the problem.
Bengaluru received unprecedented rains on Sunday night, leaving parts of the city water-logged and citizens struggling to go about their daily lives. Photos and videos from the city, of officegoers taking boats and even tractors and people wading through knee-deep water, went viral.
The Bengaluru Bruhat Mahanagara Palike said it had identified several areas that had encroachments to stormwater drains. The government announced funding for improving the drainage system in the city. Karnataka chief minister Basavaraj Bommai announced Rs 1500 crore for the draining of water in the city and another Rs 300 crore to remove encroachments.
S Vishwanath, civil engineer and urban planner, who has spent 36 years in the water sector, said in an interview with BOOM that these were "growing up pangs" for a city that was "growing at over 45 per cent every decade". He said, " There has not been enough design and investment in infrastructure in these peripheral areas."
Vishwanath explained in detail why certain areas of the city saw such flooding and what could be done to improve the city's infrastructure.
Here are edited excerpts from the interview:
What are the areas of Bengaluru that experienced flooding?
The majority of Bengaluru is not flooded. It's the pocket in the southeast of the city. Most of Bengaluru isn't floating in boats as one might see on social media. It is largely the Mahadevpura constituency, Outer Ring Road and Sarjapur.
What caused flooding in these areas?
There are several sets of issues in this pocket including the boom in development there from office to residential space, and road construction. There has also been a spell of unprecedented rain that has caused the recent flooding.
What we have in Bengaluru is what we call a cascade of tanks (lakes). Now when one fills up, a door closes, and it goes to the next tank through a channel. The water eventually drains into the river. This link (channel) in many places is broken, and that can cause flooding.
Can this be attributed to the lack of infrastructure?
The city is growing at over 45 per cent every decade. It is one of the fastest-growing cities (economically) in the world. These are growing up pangs, especially in the periphery of the city. The majority of the city has been well-invested, in terms of infrastructure. There has not been enough design and investment in infrastructure in these peripheral areas. That will change after a catastrophe like this. It's how Indian cities and infrastructure development work. It's not unusual at all and not something that cannot be handled with infrastructure development.
For a city that generates 50 per cent of the state's GDP and has so many international brands stationed, we are heavily underinvested in.
If it's done wisely without any corruption, it will be resolved.
Is this a problem unique to Bengaluru?
No, not at all. In fact, coastal cities like Mumbai and Chennai that are subject to high tides and very heavy rainfall have it worse. Bengaluru on the other hand is blessed with a topography. There is a ridge line running through Bengaluru and it falls away to the right and left of this line. To the left of the ridge line is the Cauvery basin where the ground slopes from north to south and it's a very steep slope. Any water collected on this side, quickly cascades through the slope and gets drained. To the right, is the Dakshin Pinakini basin, which flows from west to east and is a gradual slope. The water thus flows slowly. So, this side of the city needs better design of stormwater drainage in comparison.
We have to work with this natural advantage. The disadvantage is that real estate prices have shot up so much that every square inch of land is coveted. The space for lakes and drains is compromised and needs to be protected.
Is flooding being caused by building on lake beds?
Every one of the lakes in Bengaluru is a human-constructed tank made for the purpose of irrigation of paddy crops. These water bodies were meant to hold water for a certain period of time. Now, the paddy crops have gone and these lake beds have to find a new role. They have to be redesigned to protect the city from waterlogging and as open spaces.
Unfortunately, we are stuck in a nostalgia trap. If people have built on these tanks, it is because they were not being used and their legal identity has not been made public. We don't have a map that will tell us if a particular lake or a nalla (connecting the lakes) has been built on. If that information is in the public domain, people will be able to decide not to build on or buy in these areas.
In the 70s, malaria was a big issue in Bengaluru. At that time the recommendation of a government committee was to drain these tanks as they were becoming breeding grounds. Even during the plague, the connectors to the lakes were breeding grounds for rats. There have been times in history when certain decisions were taken. We seem to have forgotten all that.
We need better storage networks, better solid waste management networks, and we need road and transport networks that don't interrupt the flow of water. These three in tandem with stormwater drains can resolve the problem.
Is it true that Old Bengaluru has fared better?
Old Bengaluru is not flooded like the newer pockets because we have invested in the sewage networks in these areas. We have built stormwater drains that can hold large quantities of water, and drain it out. The lakes have been redeveloped in many areas and don't contribute to flooding.
How can southeast Bengaluru be protected from flooding?
This region also has a unique hydrological problem. The land here is flat, unlike the West which has steeply sloping land that helps water drain out. Hence, when such land gets developed, we have to invest in stormwater systems quickly to help avoid such situations.
We also do a very bad job of road development, where roads act as dams and barriers instead of allowing water to flow to the drains.
The short-term solution is to drain the water into the lakes which the city is already doing. The long-term solution is to develop a permanent sewage network that is designed for the high-intensity rain that we are experiencing due to climate change. This has been documented clearly by the Comptroller and Auditor General of India in the performance audit of the Management of Storm Water in the Bengaluru Urban area. It was also the first time that an official body said that there was no map of stormwater drains in Bengaluru.
What about the media reports that suggest the city is drowning?
This is not true. We had reports two years ago that Bengaluru will run out of groundwater, and will become the next Cape Town. Then there were others that said half of Bengaluru will have to be evacuated. This is all hype that has not come true.
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