Faulty execution in BBMP SWD works has led to floods

What is required are a system of data monitoring, an integrated watershed management approach, and a hydrological study of the drain network.

In May 2022, Bengaluru’s flooding issues prompted Chief Minister Basavaraj Bommai to announce modernisation of these drains in an integrated manner, at a cost of Rs 1,600 crore.

BBMP then authorised zonal commissioners to take up emergency work worth Rs 1 crore and this included removing silt in all drains. The BBMP engineers were also directed to identify low-lying areas and other vulnerable areas in the city. Housing Minister V Somanna stated that all engineers would be held responsible if flooding persisted during monsoons. The August-September 2022 rains did see more flooding. But no official was hauled up.

Removal of drain encroachments: Recent action by the state

The Karnataka High Court has hauled up the government for allowing sewage lines to be connected to SWDs. In one instance in Vinayaka Layout, Anekal, the authorities had allowed construction of an underground drainage (UGD) system connected to the SWD.

BBMP has taken up action against encroachments and obstructions on SWDs. They demolished a wall and pathway blocking the SWD leading to Bellandur Lake, at RmZ Ecospace on Outer Ring Road. Officials demolished compound walls of three residential units in Dodda Bommasandra in Yelahanka zone and walls of TZed Homes in Varthur, which had extended to the SWD.

BBMP is carrying out a technical survey to check feasibility of alternatives like diversion drains to demolishing houses that have encroached on SWDs at Rainbow Drive, Sarjapur Road. However, residents from the adjacent Junnasandra village feel that the diversion would lead to their village being flooded. Varthur residents also demanded that kaluves for cash scam be probed by the NGT.

The chief minister then announced that an exclusive master plan will be prepared for Mahadevapura, to ensure flooding does not recur. The BBMP has also planned to appoint nine disaster management officers to tackle flood situations, and establish a dedicated cell for disaster management.

A survey by the Karnataka Public Land Corporation (KPCL) and the Karnataka Tank Conservation and Development Authority ( KTCDA) in September showed of the 837 lakes in Bengaluru 734 are encroached. The State Cabinet recently cleared a Rs 350 crore BBMP action plan to build stormwater drains, in places affected by the recent floods.

More recently, the BBMP’s own lake division announced the release of Rs 35 crore for flood mitigation projects. They propose to install crest gates/metal barriers at 160 lakes by April-May 2023.

Ad hoc, piecemeal approach to roads and drain building

As we have seen earlier, while BBMP commissioned a masterplan of drains, many of the volumes in the  documentation are actually missing. Not surprisingly, neither these documents nor BBMP’s own guidelines are referred to when constructing road infrastructure.  

Even Bengaluru Smart City Limited that had taken up road infrastructure of 32 roads faced flak for the quality of work undertaken when streets flooded when it rained. They claimed that only “individual roads were taken up, and were not aware of the complete stormwater drain networks and that rainwater that flows into developed streets that were redeveloped from adjacent streets not under their purview”. 

In October 2022, it was reported that a proposal to adopt underground flood water retention basins, also called monkey’s cheek solution, was being considered in low lying areas and  one such solution would come up in HSR Layout. However, the proposal was still at a conceptual stage. In another case, the BWSSB had reduced the width of a primary stormwater drain, to build an underground drainage, near Embassy Manyata Business Park, destroying the natural drain. Other complaints include, drains being laid out unscientifically in Hongasandra, sewage pipes unchanged for the past 15 years in OMBR layout,  unfinished work or slow pace of work, choked drains

The CAG had pointed out that various departments mapped underground utility differently. For example, BWSSB adopted old maps from 2002, and that resulted in a mismatch of actual location of utilities – some of the lines of sewage pipelines were shown overlapping with buildings. The BESCOM used two dimensional format for the GIS maps, and only captured the length of underground cable, neglecting data of the depth at which the cable was laid. The report also stated the lack of data validation, as not only each viewed data differently, there was no system to correct inaccuracies or even allow for a comprehensive compilation. 

There was also a recent case where the concrete wall of the shoulder drain collapsed within a week of construction at 24th Main Road in HSR Layout, pointing to the lack of quality controls.

Trend towards concretisation of drain infrastructure

“Concretisation of the drains and other catchment areas is another major problem. Given that Bengaluru‘s drains are connected to the natural river valleys, reinforcing these drains with concrete serves no purpose,” says Kshithij Urs, Adjunct Professor Public Policy, National Law School. A 2017 study by the Indian Institute of Science titles Frequent Floods in Bangalore: Causes and Remedial Measures, says that the reason for frequent flooding since 2000, even during normal rainfall is “a consequence of the increase in impervious area (paved surfaces have increased to 78%) with the high-density urban development in the catchment and loss of wetlands and vegetation.” The study also points to the narrowing of drains and their concretisation, impairing hydrological functions of natural drains.

In the National Green Tribunal (NGT) case related to Bellandur Lake, the BBMP had submitted in 2019: “The concretization of SWD is avoided in all big rajakaluves having width more than 4.00 mtrs. However, due to development/ construction of buildings by the side of Rajakaluves, the retaining walls are unable to withstand the exterior pressure. At these points after technical verification the ‘U’ shaped drain is constructed, with the intermediate previous section/holes in the form constructed, with intermediate previous section / holes in the form of circular openings for enabling recharge of ground water, where the width of the land available for Rajakaluve is less than 4.0 m. Channelization of stormwater drains is being avoided in the outskirts of the city and natural flow of the Rajakaluves is allowed, especially the downstream flow of Vrishabhavathi Valley, Challaghatta Valley, Hebbal Valley and Koramangala Valley ”.

Yet concretisation continues. In June 2022, Bangalore Smart City was hauled up for modification and diversion of SWD in Cubbon Park. However, S Vishwanath, water expert, feels the non-concrete approach is not practical, “The increased run-off due to increased hard surface and higher intensity of rainfall means the major drains will need to be concretised.” He says the current approach leads to significant erosion and affects slope stability along drains.

Sewage and treated water let into stormwater drains

“Our drains are being constantly abused. Sewage discharge is a prominent violation”, says Myriam Shankar, Founder, The Anonymous Indian Charitable Trust, which runs the Namma Jalamarga Campaign. “The reason for this is a policy ambiguity across the board and a lack of responsibility”, she adds.


Read more: Lack of stormwater drain planning in Bengaluru is a risk factor for future floods


What’s more, in some places sewage lines have been laid inside the SWDs, though the BWSSB Act, 1964 prohibits this. Even if not sewage, it is common to see treated water let out into drains, though the law prohibits this too. The government has mandated Sewage Treatment Plants (STPs) for residential apartments, commercial properties, educational institutions and townships above certain sizes. KSPCB regulations mandate treated sewage be completely reused for non-potable purposes like toilet flushing and watering gardens – but the “zero discharge” policy is silent on what to do with excess treated water.

Desilting rarely done

Comprehensive desilting activities are not properly planned or executed. Secondary, tertiary and roadside drains are often ignored, which further compounds the problem. “We realised in the course of our work on the K100 Citizen Waterways Project, that it is important to look at all the connections to K-100, with secondary and tertiary drains”, says Amrita of MOD Foundation, which worked on the K-100 Waterway project.

Garbage being removed from Silk Board drain.
Desilting and garbage removal at Silk Board drain. Pic: Pinky Chandran

However, for the rest of the city, there appears to be no uniform plan. What happens after the drain has been de-silted? It’s a common sight to see mountains of silt, mixed with garbage and sewage on the side of the roads. The recent case of HSR layout is a case in point, though the BBMP had introduced the ‘silt and tractor’ scheme and set aside Rs 15 lakh per ward to employ labourers, a tractor, and a driver round the year to attend to local works.

In 2017-18, the BBMP had introduced the system of annual maintenance for SWDs and had awarded the work to a single contractor to maintain the entire stretch of 450 kms. In July 2022, the BBMP called for separate agencies to manage the stretch of 573 kms ar a cost of Rs 47.39 crore annually, for three years. While each bidder can only undertake 32 packages, the audit mechanism appears to be ambiguous and vague, as in the previous contracts.

Rainwater down the drain

The entire stormwater run of the system – including lakes – where water collects should be treated as rainwater structures”, says Ram Prasad.  Rainwater harvesting systems  are currently underutilised, as there is no strict enforcement. Given that SWDs are meant to capture storm/rain water, what we also need is an integrated approach that works on rejuvenating lakes, improving aquifers, and recharging open wells. “The problem is that no one understands the interconnections across rain water, ground water, storm water and lakes”, says Ram. 

The CAG Report 2021  points out that water run offs are not being considered as a potential resource despite growing scarcity and demand for water in the city.  According to the BWSSB, only 40,242 houses in the city harvested rainwater. Post the recent rains, the BWSSB reported that they had surveyed 8, 500 buildings, disconnected connections at 3, 000 houses and issued notices to about 400 houses. The fact also remains that most government buildings including the BBMP council building does not have any facility to capture rainwater. “Selective penalising by the BWSSB is a serious issue, they must get their act together and issue notices to all government departments as well”, says Ram Prasad.

While the Karnataka Water Policy, prepared by the Karnataka Jnana Aayoga (Karnataka Knowledge Commission), recommends the need to recognise the two-way link between groundwater and surface water and recognition of aquifer as a system that connects ground water, protects recharge zones and carry out aquifer wise regulation, there has been no visible effort yet. Recently, though, the Mahadevapura Task Force launched ‘Catch the Rain’ campaign, hoping to clean 26 kalyanis, desilt 15 lakes, in addition to identifying other places such parks, government buildings and public areas and developing 231 collection pits.

Last year, the BBMP was hoping to receive Water Plus Certification under Swachh Survekshan 2021.  The requirements cover a range of issue, including a declaration from ward councillor that wastewater (black water) from all toilets is being discharged into a sanitary outlet, well maintained, and connected SWDs, no sewage outflow from wastewater water conveyance system, no untreated sewage discharged into open environment, mechanical cleaning of drains  and a minimum of 25% of the wastewater being reused after treatment at the city level for horticulture, agriculture industry and cleaning roads.

Like with the clean city rankings, this too seems like a far -fetched dream. In November 2022 it was reported that the BBMP was setting up rainwater harvesting pits to avoid floods. A target of 5,000 rainwater harvesting pits is to be installed in parks and roadside drains in three years.It  remains to be seen if the BBMP can make this a reality.

Drains are dumping ground for garbage

Improper solid waste management is another huge problem affecting SWDs in the city. In many areas, where low income communities reside, waste collection services have been lax or are missing. Too many temporary solutions, including installation of the semi-underground bins have been made as a band aid solution. However, on ground, there has been no engagement with the communities, and no effort to implement the SWM Rules 2016.

A garbage filled drain.
Drains as dumping ground. Pic: Pinky Chandran

Read more: A historical lens on Bengaluru’s drains


An over-the-surface inventory of the garbage in the drains will find a range – from mixed waste tied to plastic, to textile waste, from construction debris to animal waste and carcass of dead animals. “Post our recent campaign to streamline waste collection around Rachenahalli SWD, the BBMP started collecting solid waste from three low income communities along the drain. The result was astounding, as the BBMP was able to collect 7,000 kgs of waste from 183 households in one month. That is a decrease of seven tons of waste going down the drain”, says Myriam.

Just announcements, no action

In July 2016, Bengaluru was again at the mercy of the heavy rains, receiving 90mm rainfall in a span of 12 hours, which resulted in severe flooding. The then Chief Minister ordered for the clearing of all encroachments on stormwater drains. The BBMP was found scrambling. The numbers doing rounds were that a total of 1,923 encroachments had been identified and of that, 800 were cleared. However, there were complaints that the BBMP was using old revenue sketches and survey maps prepared decades ago to identify encroachments on SWDS. Malini Ranganathan in her paper points out that removal encroachments form a centrepiece of flood remedial measures and questions what gets labelled as an encroachment in the first place matters.  

Cut to November 2021,  the BBMP again said it intended to clear 714 encroachments on SWDs. That’s when unprecedented rains lashed Bengaluru that resulted in excessive flooding in Yelahanka and Byararayanapura assembly constituencies, the Chief Minister directed officials to draft a drain master plan to widen the rajakaluves and build diversion canals, and debated on demolishing illegal structures to free the city’s storm water drains. It was deja vu. A mere statement of intent just like in 2003, when the then Bangalore City Corporation promised respite from flooding. A promise that has been unfulfilled  for the past 19 years.  The answer to  what structures are being saved, and what are being demolished remains elusive.

A saga of announcements and money spent

  • February 2003: Scientific clearing of SWDs, modernisation of SWDs in all the valleys, promise of no sewage in the drains.
  • June 2018: CM asks BBMP to prepare detailed plan on SWDs. The BBMP said they had used government funds worth Rs 800 crore and worked in all zones, particularly RR Nagar, Bommanahalli and Mahadevapura, and had fixed 242 culverts and rectified 339 vulnerable spots.
  • December 2020: Bengaluru Mission 2022 launched : To upgrade the city’s infrastructure and a task force to monitor progress. Some of the projects included restoration of 25 lakes and monitoring water quality in 25 lakes; waterway beautification of raja kaluves.
  • November 2021: CM instructed preparation of detailed project report for SWD drain widening and building diversion channels and special package of Rs 900 crore.
  • April 2022: BBMP said they will set up control rooms in all 28 Assembly segments to respond to flooding complaints.
  • May 2022: CM promised the government will focus on long term measures such as desilting drains, developing valleys, removing encroachments and enhancing sewage treatment plants
  • May 2022: CM announces setting up of zonal-level task force  to oversee all development work in the zone and be a nodal agency in times of floods.
  • June 2022: Special Task Force to clear SWDs.
  • July 2022: Separate agencies to desilt rajakaluves: Estimating the annual maintenance contract for maintaining the 573-kilometre SWDs, BBMP floated a three year tender for a total expenditure of Rs. 142.18 crore.
  • September 2022: the chief minister acknowledged that Rajakaluve development will take time as the city has 633 rajakaluves spanning 859.9km; 490.1 km of primary and secondary drains have been developed and the remaining 469.9km are yet to be covered.  He said government has earmarked Rs 1,500 crore to develop mega stormwater drains to prevent flooding.
  • Oct 2022: Government announced Rs 329 crore to flood proof IT corridors, under the CM special grants. Bangalore Mirror also reported that the BBMP had spent around Rs 2,000 crore on remodelling 389 km of drains by building retaining cement walls. The government also sanctioned Rs 350 crore to BBMP to flood proof the city. A large portion of the money is to be spent on restoring the missing links between the city’s lake networks, with the remaining Rs 33 crore to be spent on building sluice gates in 148 lakes across Bengaluru. Post this, the BBMP aims to showcase 850 kms of concretised storm water drains. However, the question on concretising still has experts divided.

So what needs to be done?

The question doing the rounds is if the city is investing enough in SWDs. But the question to also ask is on what basis are these decisions made? Are there data monitoring indicators and course corrections in the planned investments? Are they being completed on time? What action is taken when the projects are not completed on time? What we need is a robust system of data monitoring. “What we also need is an integrated watershed management approach and a comprehensive hydrological study of the drain network”, says Ram Prasad.

We also need to put people at the centre. As Srikumar Chattopadhyay, ICSSR National Fellow puts it, “We need a hydro-social cycle approach to water management, as it repositions the natural hydrological cycle in a human-nature interactive structure and considers water and society as part of a historical and relational-dialectical process.

This article is part of a series ‘As the drain goes’, a joint project by Pinky Chandran, Nalini Shekar, and Citizen Matters, and is supported by the Bengaluru Sustainability Forum (BSF).

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