Urban flooding has become common in the low lying areas of Bengaluru. As a result, people are dealing with murk, stink, and diseases in flood–prone areas.
It was a warm March afternoon. The cars were parked in front of the houses on the sloped street that led to the lake. A few brown leaves were scattered here and there on the pitch-black road. It is hard to believe that the street turns grim and slimy when it is monsoon and the lake is overflowing.
The Main Tank Shore Road near BTM layout is facing water logging for the past four years during heavy rainfall. Rajsekhar, a resident said, pointing at the lower part of the freshly painted black gate of his house, “The water reaches till here.” Though it stays for three-to-four hours, the area gets dirty, he added.
Rajsekhar has been living in Bengaluru for 20 years. His two-storey house is situated in the lower part of the sloped street. When the water level rises in Madiwala Lake, it flows into the streets and submerges the adjacent areas.
Puja, another resident said, “If it happens at night, it becomes problematic.” She added that her house is on the upper portion of the street, so the water does not reach up to her house, but she cannot go out at night in case of emergency because of the water logging.
A study by the National Institute of Disaster Management states that in recent decades Bengaluru has reported a series of urban flooding cases. A case study by Mysore University states that Bengaluru has 134 flood-prone areas. BTM Layout is one of them.
Urban flooding impacts a city in many ways. Beruj Kumar Swastik, an urban planner from Urban Landscape Design Studio in Bengaluru, said, “Flood damages all the infrastructure — roads, fibre optical cable lines, buildings — it damages a lot in the city. It creates traffic jams.”
Karnataka State Disaster Management Plan 2019-20 report states that 5,764 kilometers of roads, 11, 537 houses, and transformers and electric lines were damaged due to flooding in 2013-14. In 2014-15, the infrastructure damage due to floods was Rs. 570.30 crore.
Flood does not cause infrastructural damage only but also impacts public health also. Swastik talked about the flood’s impact on public health and how it affects poor people more compared to rich people. He said, “We get malaria and dengue in the rainy season. The poor suffer more. People who are rich, they sanitize their area and stay safe, but poor people have to stay in water-clogged area where mosquitoes breed, and dengue spreads.”
Swastik’s description matches Bashona’s situation. She is a migrant worker and lives in a slum near Yeswanthpur. Her house is nothing but pieces of tin. She works as a domestic helper in nearby apartments and her husband works at a construction site. Their three children are in West Bengal. They send half of her income home for their studies.
Bashona said, “This place floods a lot. It stinks. Flies and mosquitoes increases during flood. Nobody comes to clear the water.” She added when it starts to flood we have to shift our belongings and if we are not quick, we lose some of them. The area stays submerged for five-to-six days once it floods. She cannot cook in those days and gets food from her employer’s house.
After the water gets cleared, they clean the dirty slush from the makeshift houses that have no floors. Bashona said that it smells for several days even after the clean-up.
Her slum, located beside a canal that flows into Nagavara Lake, has no concretised surface, no sanitation system. Now, whether they take bath, dumps garbage, it stays right there on the land beside their makeshift tin houses. The unhygienic situation amplifies the spread of diseases. Bashona said that a child, just two or three houses away from hers was diagnosed with dengue. She said that dengue is common in her area.
The impact is worse on the poor because for a better income they come to big cities and end up in slums. Bengaluru topped the SDG (sustainable development goal) Urban Index for decent jobs and economic growth. The city has 387 notified slums. In 2017, one-fifth of Bengaluru’s population lived in slums.
Urban Flood Management — A Case Study of Bangalore by Mysore University states that most slums of Bengaluru are situated in low-lying areas.
The people who live in slums are cut off from mainstream development. Mostly, there are temporary, unsafe houses made of tin and plastic sheets which are vulnerable in situations like flooding, states the case study.
Swastik explained how the flash flood indicates Bengaluru’s poor water management. He said that because of flooding the city has water scarcity. People think because of excess rainfall the city is getting flooded. No, the city gets flooded because it cannot absorb the natural water. All the rainfall water gets drained out of the Bengaluru and Bengaluru faces water scarcity.
Frequent Floods in Bangalore: Causes and Remedial Measures, a technical report states that due to urbanization, the concretized surface grew 1028 percent from 1973 to 2017. The impermeable roads do not let rainwater penetrate into the ground. It runs off the surface and gets wasted. The annual rainfall water yield is 14.80 thousand million cubic feet in major valleys of Bengaluru, reveals the Performance Audit Report of Storm Water Drains in Bengaluru 2021.
Dr. G.S. Srinivasa Reddy, consultant at Karnataka State Disaster Management Authority (KSDMA) states, “The population was four lakh in the 1940s and now it is 1.27 crore. Now, 90 percent area is covered in concrete, so, the runoff has increased. Suppose Bengaluru gets 32–40 millimetres of rain fall, out of these 36 millimetres of rainfall are running off the surface.”
Once known as the city of lakes, Bengaluru witnessed a rapid decrease in water bodies. It had 1,452 water bodies in 1800 which had a storage capacity of 35 thousand million cubic feet. In 2016, there were 194 water bodies with a storage capacity of 1.2 thousand million cubic feet.
The decline in the number of water bodies is visible in the maps
Swastik said that encroachment of lakes, catchment are another factor that is adding to the problem. He said, “It (flood) has started because of the encroachments of the catchment areas. Suppose one fills up a lake and builds an apartment on it, but the same amount of rainfall will happen in that area. Now, there’s no place to hold and absorb the water. Where will the water go? It will inundate the surrounding area.”
“In Koramangala and Challaghatta valleys, there is more water logging because many of the layouts are built in old lakes. The reason is the tank beds could hold water but they no longer hold water, so the place gets waterlogged,” explained Vishwanath.S from Biome Environmental Trust, an organization working to educate and implement sustainable land use planning.
Moreover, storm water drains are being encroached on, and the width is being reduced. According to the Indian Institute of Science (IISC) 2017 study, the storm water drain connecting Bellundur Lake to the city market side reduced from 60 meters to 28.5 meters.
The catchment of Kaikondanahalli joins Bellandur Lake down streams, but the catchment is now filled with commercial and residential buildings, revealed IISC 2017 study report. The study report further states that the drains connecting Bellandur with Varthur lakes are being turned into mixed-use areas (commercial and residential).
Waste is being dumped into the catchments and water bodies which is making them incapable to hold rainfall waters. Vishwanath explained how sewage and the dumping of solid waste cause flooding. He said, “Arkavathi and Vrishabhavathi valleys are steep so the water runs off fast. But, because the Vrishabhavathi river itself has been choked, it causes flooding near Gali Anjaneya Temple.”
Moreover, storm water management is poor in Bengaluru, states Performance Audit Report of Storm Water Drain in Bengaluru 2021. The report states that Karnataka has no specific framework to maintain the storm water network of the city.
The designs of the storm water drains have faults that don’t let the storm water drains carry water during heavy rainfall. An official from the Storm Water Drain Department, Bruhat Bengaluru Mahanagara Palike (BBMP) said, “The drains are connected to the storm water drain at a 90˚ angle. So, what happens, during heavy rain the main storm water drains are full and the water is flowing in a different direction, now this flowing water prevents the smaller drains’ water to enter the main storm water drain because the flow direction is different.” He added the design needs to be changed; smaller storm water drains needs to be connected with the main storm water drains in an angle that matches the flow direction.
Now, the question is what is to be done to make Bengaluru sustainable in water management. Swastik said that there are several solutions, but the simplest one is to remove the encroachment from the storm water drains and lakes. He said, “If all the catchments are removed, the problem will be solved. It’s a very simple solution, but tough to implement.”
He added, “Indian cities have very well managed ecosystems. The issues like flooding they are facing because of mismanaged urbanization. Now, because you have already encroached on the lakes, you are not able to go back to the earlier position. So they are coming up with rainwater harvesting, and storm water drains.” He cautioned that water is limited and an important resource. Unlike power, it’s not possible to generate more water if we want. The only way is to manage it efficiently.
Apart from removing the encroachments, rejuvenation of lakes, improving the storm water networks and rainwater harvesting are important. T.V Ramachandra who is the writer of the Frequent Floods in Bangalore: Causes and Remedial Measures said that lake rejuvenation is very important to stop urban flooding. Rainwater harvesting and lake rejuvenation both need to be done side by side. But lake rejuvenation is more effective because the groundwater reserve is under the lakes. The lakes are faster in recharging the groundwater levels.
BBMP, Lakes Department has developed 65 lakes, and 24 lake development projects are underway. The official website shows that 3622 encroachments have been removed from live lakes. BBMP manages 167 lakes while Bangalore Development Authority (BDA) manages 33 lakes. Apart from this, BBMP conducts silting works in lakes to keep its water holding capacity intact.
The Karnataka State Legislative Assembly passed Bangalore Water Supply Sewerage Bill (Amendment) 2021 mandates that every building, measuring 60✕40, will harvest rainwater and use it for internal purposes except cooking and drinking.
A.R Shivkumar, principal scientific officer, Karnataka State Council for Science and Technology, who helped in developing the rainwater harvesting system said, “Basically, rainwater is a primary source of all water. If you don’t have a river close by, it becomes more important. We get around 1000 thousand million cubic feet of water. So, if you have a plot by 60✕40 feet, you can get around 20,000 to 200000 thousand million cubic waters in a year. It’s more than sufficient for your requirement.”
Reddy said, “We’re monitoring urban flooding with water sensors. There are around 100 –120 water sensors in storm water drains in flood-prone areas. Once the water level goes up 75 millimetres, it indicates heavy rainfall and probable flood, and we start working to clear the water immediately.” Reddy added that Karnataka Natural Disaster Monitoring Centre (KNDMC) has launched Bengaluru Megha Sandesha application as a part of the urban flood management model. The application provides data about weather, storm, rainfall, flooding, and lightning. A web portal, Varuna Mitra was launched to spread information about rainfall.
Indian Institute of Science in collaboration with KSNDMC developed Urban Flood Model for Bengaluru. The aim is to give an accurate forecast about urban flooding to manage the situation on the ground. However, the site has only the first annual meeting’s data which took place in 2019 before the pandemic confined people to their homes. Moreover, BBMP’s 2021-22 budget estimate report shows that there’s no expense on flood management work since 2019.
Meanwhile, the city continues to see flash floods. This year, in pre-monsoon rainfall in mid-April, the southern parts of Bengaluru were waterlogged, reported a local newspaper. Once again, Bashona’s tin house was flooded; Rajsekhar’s freshly painted gate submerged in filthy water; Puja was locked inside the room.