Fixing its Development Plan might be the solution to Mumbai’s flooding woes

A Mumbaikar’s daily routine consists of going to work, eating vada pav and hustling to reach back home as early as possible. However, when the southwest monsoon arrives, the working class faces a stark reality — the rains are anything but romantic. Instead, they bring a deluge of challenges, from flooded streets to disrupted commutes, crippled local trains, and a loss of livelihood — making the working class lose 63 per cent of its productivity.

In July 2023, Mumbai received 1,512.66 mm of rainfall, according to the India Meteorological Department, breaking the earlier record of 1,502.6 mm in July 2020.

Meanwhile, the city’s failed relationship of managing rainwater became more evident as a 10 per cent water cut continued in the same month. According to the MCAP (Mumbai Climate Action Plan) 2022, more than 35 per of the city’s population lives within 250 metres of chronic flooding hotspots. 

Harnit, an IT consultant, survived the Mumbai July 2005 floods and lost most of his family assets as his house was on the ground floor. The floods were a once-in-a-hundred-years event, with the city receiving 944mm rain in 24 hours. “Slowly, the water entered our ground floor house, rose to our knees and our waists,” he recalled.

Flooding at Tilaknagar affecting the residential areas. Photo: Dimple Behal

According to the Maharashtra Regional and Town Planning Act, 1966, it is necessary to earmark flood-prone zones within the development plan (DP) of the city. This can help in preparing dedicated guidelines and regulations for improving flood-resilience and reducing vulnerability in these areas. However, in the recent Mumbai Development Plan 2034, the flood-prone zones have not been identified in the proposed land use maps.

However, this doesn’t stop people from taking steps to protect themselves from flooding in these areas. Harnit said, ‘‘People (in low-lying areas) retrofit their plinth level higher than the road to prevent water from entering the premises during flooding events. Unfortunately, new construction often includes ground floor parking lots, reducing the city’s permeable areas.”

The Mumbai Development Plan 2034 and DCPR (Development Control & Promotion Regulation) 2034 provides the flexibility to develop open spaces or recreational areas on the podium in a land parcel. However, these spaces are often encroached by vehicles. Ground which would have been permeable, is thus sealed. This exacerbates problems in case a flooding event happens in a low-lying area.

About 700 kilometres of watercourses run through Mumbai and the Mithi has been a major channel of the city’s drainage network. The Mithi is usually seen today as a repository of sewer, industrial effluent, and hazardous waste. During the monsoon, the Mithi’s floodplain becomes more vulnerable to inundation whenever heavy rainfall and high tides do coincide. 

“During high tide events and heavy rains, if water flows backwards in the city rather than flowing from the Mithi river to the ocean, understand that floods are going to happen,” said Suryaprakash Shukla, an autorickshaw driver from Uttar Pradesh, who has been living in the city for the past 23 years. He migrated to Mumbai after completing school in search of better opportunities.

Even though flooding events make him more vulnerable, it doesn’t stop him from earning his living as his work doesn’t allow him to take breaks during extreme events. Shukla adapts himself by refraining from taking up rides in areas which are flooded with water. 

“Overpasses are being constructed in the city and no space is left for runoff to escape,” he added. According to estimates, 94 per cent of Mumbai has been concretised in the past four decades. Sixty per cent of its vegetation and 65 per cent of its water bodies have been lost in the process. 

“Water bodies are shrinking and are getting encroached due to development,” said Harnit. To reduce flooding risks around these water bodies, the DP suggests demarcating buffers around them and maintaining them as development-free zones.

However, due to a lack of affordable housing in the city, the development of informal settlements on these vulnerable areas has become increased. Clearing these settlements, with adequate rehabilitation of the residents, remains a critical issue. The DP does not mention these water bodies and little has been done for their protection. 

The Mumbai Metropolitan Region Development Authority has been identified as the biggest encroacher of the Mithi river, as reported by a Supreme Court-appointed Committee that submitted its findings on the river’s status to the apex court.

The Mithi river ecosystem has been encroached due to the reclamation of 600 acres for the construction of the Bandra-Kurla Complex (BKC). The committee questioned the desire for short-term real estate greed and maximising construction.

 Building at Matunga with recreational open space on podium and 6-storey parking on ground. Photo: Dimple Behal

It suggested the river capacity be increased by providing a minimum 15 metres on both sides of the river as a buffer zone, along with 50 metres of a No Development Zone, which would help runoff dissipate during heavy rainfall.

However, the classification and definition of water bodies is still missing in the DP. This poses the question as to whether areas surrounding water bodies should be opened for development.

According to (CRZ) 2019 Notification, a 50-metre buffer along tidal water bodies should be treated as a No Development Zone, while DCPR 2034 limits the buffer to a six-metre development-free zone which can even be reduced to three metres in case of nallahs.

This creates a stark contrast between the development considerations of CRZ and DCPR 2034. In 2014, the Maharashtra Coastal Zone Management Authority (MCZMA) designated the Mahim and Backbay areas in Mumbai as “bays” rather than as “shoreline”. This reduced the 500-metre buffer in these areas to 100 metres, clearing the way for development that was otherwise not allowed.

Chirag, a resident of Sion, has been living in Mumbai for the past 25 years. He said, “The frequency of flooding has been reduced from earlier, due to new systems coming up.” As a flood management technique, the Brihanmumbai Municipal Corporation (BMC) has invested 7,000 crores in 10 years to prevent flooding. 

BMC has constructed holding tanks below open spaces to hold extra water during rainfall events. This is to reduce flooding events in low-lying areas as DP 2034 allows underground parking and commercial spaces under open spaces. However, it fails the purpose of creating permeable open spaces that can absorb extra water during flooding events. 

Showing the Hindmata holding tank constructed under the park, Chirag said, “After its construction, hardly anyone comes to play in the park as it has not been levelled.” 

Holding tank constructed over the park at Dadar resulting in no utilisation of park. Photo: Dimple Behal

Shukla highlights the contrast of development in the city. “The issue of waterlogging occurs in areas which are not planned, like Kurla which gets water-logged after every shower of rain. No water-logging occurs in planned areas, even if they are near to the coast.”

As living in planned urban spaces is unaffordable, middle/lower class Mumbaikars often end up living in areas which are unplanned, compromising on living in habitable environments. Their limited adaptation capacity makes them more vulnerable.  

Chirag nostalgically recalls playing football in parks as a child and laments the scarcity of free, open spaces which have been replaced by paid turf facilities. Currently, as per MCAP 2022, the city has 1.8 square metres per capita open space as compared to the standard of 10-12 sq m per capita. The MCAP 2022 promises to increase the open space by two-fold.

To increase these open spaces, reclamation of the sea has also been promoted, leading to higher built-up footprint and surface runoff. This concretisation of the city has resulted in near-zero infiltration capacity with the runoff coefficient being as high as 1, indicating that a larger portion of the precipitation turns into runoff causing waterlogging. 

To address these issues, reducing concretisation in the city is crucial, allowing for more permeable surfaces. A balanced approach involves improving both blue-green infrastructure and hard infrastructure.

Achieving this entails amending the Development Control Regulations (DCR) to incentivise or mandate flood-resilience interventions at the plot and city levels. Additionally, open spaces should be recognised as vital infrastructure for flood mitigation and adaptation, with guidelines promoting their multi-purpose use as retention and detention areas during floods.

Dimple Behal is an Urban Development Practitioner working on the intersection of inequalities, development & environment

Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth

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