- Encroachment of lakes, tanks and drains, poor planning of drainage systems and lack of regulation of floodplains have exposed Bangalore to the threat of urban flooding, say experts.
- Multiple studies and reports have highlighted the vulnerability of the city to urban flooding. A 2017 study said that Bangalore has lost 88 per cent of its vegetation and 79 per cent of its water bodies in 45 years.
- Government data claims that the city earlier had a total of 260 lakes in the 1940s which has dropped to 65.
India’s Information Technology (IT) hub, Bangalore, was recently in the limelight as it struggled to cope with urban floods triggered by incessant rains in the last week of August and the first week of September this year.
With a 131.6mm rain in September breaking records of the last 34 years, several IT parks like Eco Space and residential areas along Outer Ring Road, Bellandur, Marathahalli, Sarjapur and Mahadevapura got inundated with stormwater for days.
But what led to this large-scale stagnation of flood waters in parts of India’s fifth most populous urban agglomeration? Experts working on urban issues, lakes and flood management have concluded that unabated urbanisation, a large-scale loss of green cover, encroachment of lakes, tanks and drains, and lack of attention towards conserving and regulating floodplains of water bodies have increased the threat of urban flooding. According to the disaster risk map of the city, Bangalore has a total of 134 flood-prone points in different parts of the city.
Now referred to as the Silicon Valley of India, because of its booming IT and startup businesses, Bangalore was once also known as the 'City of Lakes'. This moniker referred to the lakes and tanks made during the regime of earlier rulers and the British to cater to the agricultural and other needs of the local population. However, increased urbanisation seems to have changed the local landscape of the city, which is even evident publicly through satellite images of the city. The Master Plan of 2015, prepared by the Bangalore Development Authority (BDA), claimed that Bangalore once had 400 lakes. But with the passage of time, government data claims that it reduced to 260 by the 1940s and has now come down to 65.
Bangalore, owing to its undulating terrain, is home to a plethora of lakes that are interconnected by a system of canals/drains called kaluve, which ensures the transfer of excess water from one lake to another. Although the city lacks a perennial river, tributary rivers like the Arkavathi, Pinakini/Pennar and Shimsha help to drain the excess water from the city and into the Kaveri river. However, several experts and studies have pointed out the encroachment of lakes and canals leading to interference in the city drainage system.
T.V. Ramachandra, Coordinator, Energy and Wetland Research Group and Convenor at the Environmental Information System, Indian Institute of Science (IISc) is one of the researchers in Bangalore who has worked extensively on the issue of floods in the city. His research paper titled Frequent Floods in Bangalore: Causes and Remedial Measures, published in August 2017, co-authored by Bharath Aithal (IIT-Kharagpur) and Vinay Shivamurthy (SR University, Warangal), sheds light on the issue of degradation of the city and its water bodies and its impact.
His study claimed that between 1973 to 2017, the urban areas of Greater Bangalore grew by 1028 per cent. The report claimed an 88 per cent decline in total vegetation cover and a 79 per cent decline in water bodies (wetlands) during the same period, owing to cascading urbanisation. Greater Bangalore refers to the areas of the Bruhat Bengaluru Mahanagara Palike (BBMP—Bangalore's municipal corporation) and nearby areas, including eight urban local bodies and 111 villages under urban Bangalore. It was notified in 2006.
He told Mongabay-India, “Firstly, we need to accept that global warming is real and changes in climate are happening. We are witnessing high-intensity rainfall and are receiving a large quantity of water in a shorter period of time. Second is unplanned and irresponsible urban planning. We have choked up the city with concrete. If we have more concrete in a landscape, we see less water infiltration, a large quantum of water instead flows on the land (around 40 to 45 per cent).”
He also added that in the 1800s, the city had 1452 water bodies; now down to 193 water bodies. He also questioned the state government’s remodelling model of city drains, which he alleged added more problems to flood mitigation measures. “Every time budgets are announced to remodel the drains, there is nothing but more concretisation of the drains. Natural drains help in hydrological processes like recharging of the groundwater. So the more we concretise drains (at the cost of government money), the more we reduce the groundwater levels in the city. With the redevelopment of drains, the width of drains are getting reduced, making the city more prone to floods.”
According to the geographical map of Bangalore, the city lies within a valley. There are three major watershed regions along the valley towards which the excess rains during monsoons tend to flow. These include Vrishabhavathi, Koramangala-Challaghatta (KC) and Hebbal. KC Valley lies towards the eastern part of the city and is said to host a number of residential areas, IT hubs like Eco Space, and large lakes like Bellandur. It is also close to the Tamil Nadu border and the Kaveri river. During the recent floods, the KC Valley and the nearby area of Mahadevapura were majorly affected.
Nagesh Aras, a Bangalore-based environmentalist and a core member of Friends of Lakes, an environmental group, told Mongabay-India that the flooding of Bangalore is due to the lack of hydrological planning. He explained that a century ago, the city did not use any groundwater or Kaveri river water for its needs, rainwater was locally captured instead. But in the last three decades, as the city has grown, the increasing water demand has been met through water from the Kaveri river and by extracting groundwater. As a result, there is an increase in the surface water flow (rainwater and sewage). Aras claimed that the ancient drainage system is now totally inadequate to handle this flow.
“Bangalore’s old sewerage network was not designed to carry treated sewage at all! The network’s capacity falls short by 1400 MLD (million litres per day), which is one of the reasons for the flooding. Almost 90 per cent of the city's tree cover was lost in the last four decades and replaced by concrete surfaces and asphalt roads, which cannot absorb water. This results in a large amount of runoff water. Further, this water runs much faster on concrete and asphalt when compared to soil. That means the water rushes down the gradient and causes flash floods,” he told Mongabay-India.
He also added, “If we want to use the lakes as buffer tanks to mitigate the flood, those lakes must have large holding capacity and sluice gates to regulate the outflow. But most of the lakes are silted, and they don’t have sluice gates. Besides, many of the lakes are bypassed, which means that the lake cannot play the role of a buffer tank at all. The floodwater simply rushes around the lake to the downstream area. The Outer Ring Road (ORR) lies across the KC valley, so rainwater has to flow across the ORR at a few places. But the ORR blocks this water because there is no culvert. This leads to localised flooding.”
You may also like to read
History of Judicial Intervention
Bangalore’s lakes play a crucial role in flood mitigation. Bellandur Lake, one of the biggest lakes, receives drainage from three other upstream lakes and discharges its excess water into Varthur Lake, which ultimately drains the city’s excess waters towards Tamil Nadu into the Pinakini river basin.
In 1985, the Lakshman Rau Committee, formed by the Karnataka government to suggest measures to protect lakes, recommended conserving the traditional tanks, removing encroachments and desilting lakes.
However, the ground reality is far from what the Rau Committee recommended. A 2017 IISc report cites several areas in Bangalore with legal and illegal encroachments—apartments, playgrounds, markets and more—over tanks, lakes and large drains.
Since 2008, Leo Saldanha, Coordinator of Environment Support Group (ESG), has filed several cases before the Karnataka High Court (HC) requesting interventions to save the lakes in Bangalore. The HC eventually appointed a Commission headed by Justice N.K. Patil to look into the matter and recommend remedial measures.
The Patil Commission, in their 64-page-report titled Preservation of Lakes in the City of Bangalore (submitted in 2011), claimed that while farmlands in Bangalore were converted into built-up areas, many lakes were converted into residential areas and playgrounds. According to the report, areas of the Outer Ring Road, such as Agara, Ibbalur, Mahadevapura and Nagavara, which faced floods in September 2022, were built on lake areas. It also noted that the BDA converted many lake sites into residential areas like Agara, Saneguruvanahalli, Chikkamarenahalli, Kacharkanahalli, Geddalahalli, and Chelkere. The report batted for a 30-meter buffer zone for lakes where no construction should be allowed.
The High Court, in its final court order in 2012, accepted the recommendations of the commission and ordered the state government to undertake a survey of all lakes, ensure a buffer zone of 30 metres, remove unauthorised encroachment over lakes, conduct regular desilting of lakes, rejuvenate lakes, and stop the flow of sewage into lakes. However, in 2015, Bellandur Lake witnessed froth and foam on its surface—a sign of pollution due to sewage waste—which even caught fire.
Saldanha said that despite him and others moving to courts, the alleged negligence of the government towards conserving lakes showed no proper work on the ground. “When wetlands are destroyed, there is a major threat of flooding. The reality on the ground has not changed much despite several court orders and reminders to the government. We have been fighting for lake conservation since 1995. We warned of all these issues (urban flooding) long back and fought for it, but nothing changed on the ground due to the bureaucracy. Corporates are also responsible for the current condition here. A lot of corporate players from across the country and around the globe invested to intrude into the Bangalore wetlands and are equally responsible for the present conditions,” Saldanha told Mongabay-India.
Similar cases have been filed before the National Green Tribunal (NGT). The NGT, in its 2015 order, also asked the government to ensure a 75-metre buffer zone for lakes against the existing 30-metre norms. But the order was challenged before the Supreme Court later.
During the floods in Bangalore this year, Raj Bhagat, a geo analyst working with the World Resources Institute (WRI)-India, used satellite images to compare the changing urban landscape of the city over time, showing the degrading drains, increased encroachments and loss of wetlands.
He told Mongabay-India that the city administration has not given importance to the floodplains of the existing lakes as it has not demarcated the sensitive zones to prevent construction. Floodplains of water bodies like lakes and rivers play a key role in absorbing the excess water during monsoons and preventing floods. “In the Master Plan 0f 2015, prepared by the BDA, there is no flood zonation mark. We have a smaller buffer zone but no scientific demarcation of flood zones. If there is no demarcation by the government, we cannot even call such structures on the floodplains illegal. It seems the government has not given much attention to the issue and the protection of the valleys in the city. And this is not the problem of Bangalore alone. A lot of urban flooding in other bigger cities is also arising out of similar issues. The whole issue is related to urban planning and governance,” he said.
A recent report by the Administrative Training Institute (ATI), Mysore, a state-owned institution that imparts training to government officials and provides technical assistance in state disaster management plans, batted for flood zone mapping and demarcation and urban development in order to mitigate floods in Bangalore. The report said that in the absence of regulations, some urban structures have come up on these floodplains, and it would be tough to disturb them, but the time is ripe to make these regulations and discourage future construction on sensitive floodplains of lakes.
The report advocated that any areas around water bodies which are likely to be affected by floods in 10 years should be reserved for gardens, parks and playgrounds only, and no buildings should be constructed in such zones. Areas likely to be flooded in 25 years should be allowed to have restricted buildings with certain conditions like the number of stilts, minimum plinth level, and prohibition of construction of basements, among others.
This story was originally published on 23 September, 2022, on Mongabay.
