Despite hundreds of crores spent on desilting, why Mumbai could still see flooding this monsoon

A BMC press note assures citizens of corrective action taken in 169 flood-prone spots and ongoing work at 43 spots, but what Mumbai really needs is sustained, hydrology-based water bodies management.

It is that time of the year again. When it rains, rather pours, in Mumbai ( the Mumbai region has the second highest rainfall in the country after Cheerapunji). And then the blame game begins to divert attention from the flooding of the city, loss of lives and livelihoods, and health issues. 

Brihanmumai Municipal Commissioner (BMC) Iqbal Singh Chahal claims that the city is all set to meet the rains with its over 2900-km long storm water drain network — all desilted and cleaned up, despite the COVID crisis and large-scale labour migration. Chahal announced that BMC has already surpassed its target of desilting drains by accomplishing 113% of the scheduled work. But opposition leader Ravi Raja says only 40% of drains have been desilted.

“Desilting is an annual money-spinning exercise,” says Debi Goenka, environmentalist and activist. “Given the fact that the natural drainage system of the city has been destroyed, desilting is no solution to prevent flooding, yet there is convenient silence on this subject given the large sums of money involved. Instead of protecting the natural drainage systems and water bodies, money is being spent on pumping rain water into the sea”.

“Every year, about Rs 700 crore is spent in just two months, April-May, on desilting; Shouldn’t the drains be kept clean round the year? Why is this done only just before the monsoons?”

Gopal Jhaveri, co-founder, Rivers March, a citizens’ initiative to save the rivers of Mumbai

Recommendations ignored

The 2006 report of the Madhav Chitale committee, set up after the unprecedented flooding on July 26 2005 that claimed 546 lives, had noted that while budgetary allocations to the storm water drain (SWD) department (the SWD got Rs 912.10 crore as capital expenditure, which is 6% of allocations in BMC’s 2020-21 budget) were largely ignored, there seemed no issues with allocating funds for desilting work.

The BMC issued a lengthy press note assuaging citizens that it had taken corrective action in 169 of the city’s total 336 flood-prone spots with work on at 43 spots, while 70 remedial works in 70 spots would be tackled post-monsoon. About 334 pumps have been installed to pump out flood waters from low-lying areas by spending Rs 32.33 cr as per the BMC budget. 

Also, this year, Mumbai has installed I-FLOWS, an integrated flood warning system, that can forecast flooding six hours to three days in advance giving the BMC enough time to deal with the situation. “With the availability of advance information, it will be possible to mobilise machinery ahead of flooding anywhere in the city,” Iqbal Chahal told the media.

Rain related incidents have been claiming many lives almost every year. In 2019, a wall collapse due to rains had claimed 24 lives and injured 78 others. The United States Trade and Development Agency (USTDA) had estimated losses worth Rs 14,000 crore caused by flooding in Mumbai between 2005-2015. 

Vanishing rivers and streams

The Chitale committee report blamed encroachments on riverbeds and basins, including by government agencies, concrete waste dumping  and filling up of ponds and natural catchment areas for the floods.

Key findings of the Chitale Committee Report

  • The city’s four rivers, Mithi, Oshiwara, Dahisar, and Poisar had become creeks, with some creeks becoming dirty nallas as they made their way to the Arabian Sea.
  • Streams like Mahul (which the report said should be termed a river) had completely disappeared from the city’s development planning maps.
  • Rivers like Mithi had been diverted to make way for various projects, without giving much thought to the adverse consequences to the city. 

The report wryly observed that it was repeating what earlier committees on flood mitigation, the Natu Committee report (1975)  and Brimstowad report (1993), had recommended: to de-clog natural streams from encroachments and ensure uninterrupted flow of runoff water into the Arabian Sea.

The Committee strongly  recommended hydrological study, integrated planning of developmental infrastructure in Mumbai’s urban spaces apart from in depth attention to environmental management of  catchment areas and river basins. It observed that the earlier reports had largely been ignored and hoped that its report wouldn’t meet the same fate.

Which in fact it did, as it has been occupying some bureaucratic shelf since it was submitted in 2006!

Today, with the city facing a climate change challenge leading to change in rainfall patterns and rising sea levels, a sustained hydrology-based city planning system including flood management is the need of the hour. If the BMC doesn’t listen to its experts, reiterating the same advice time and again will provide no relief to the maximum city this year too.

Instead, the BMC has sought technical assistance from Japan International Co-operation Agency (JICA) for setting up a flood mitigation system based on underground reservoirs, shafts, tunnels and piping system as launched in Tokyo and Yokohama. Rs 5 crore has been earmarked in this current budget to assess its feasibiltiy.

Of the total eight Storm Water Pumping Stations (SWPS) planned, six have been set up at Haji Ali, Worli (Lovegrove and Cleveland), Juhu (Irla), Parel (Brittania) and  Andheri (Gazdarbandh) as part of the flood mitigation measures. 

The Mithi river

To give just one example of the administration’s indifference to the basic recommendations of  various committee reports, the Mithi river was found to have been diverted by 90 degree angles at four points to make way for the Santacruz airport runway extension between 1976 to 2005. The July 2005 deluge saw the gush of water breaching the airport walls and flooding the runway.

“City governance seems more about controlling the rivers than about understanding them and allowing its natural dynamic flow. There is no systematic thorough study done, no designed city master plan that seeks engagement with rivers; rivers are viewed more as a flood problem.”

Vikram Pawar, Conservation Expert, Water Environs

The Chitale committee report had found that two water bodies (ponds) on the runway seemed to have been reclaimed probably aggravating the flooding. “You can’t fool around with rivers like that,” said Goenka, executive trustee of the Conservation Action Trust. “In fact, the mouth of Mithi river has also been restricted at Mahim Bay due to the Bandra Worli Sea Link. Some of these developments are irreversible.”

Not just private builders, the government too is guilty of reclaiming land in catchment areas at Gorai, Charkop and Versova to build bus depots, public  housing projects and had allowed private colleges and even a theatre (IMAX), all of which have encroached on wetlands, creeks, coasts and mudflats aggravating the risk of flooding.

The Chitale committee has now sought a time-bound program for restoration and rejuvenation of urban ecosystem like creeks, ponds, rivers, lakes and coastal zones apart from restoring mangroves ecosystem and doing environment upgradation of hill slopes. 

Mumbai originally comprised seven islands connected with reclaimed spaces and flattened hills. Almost half the city area and five-fourths of suburban areas in Mumbai is reclaimed land, with 45 of the total 186 outfalls discharging water situated below the sea level, according to the Chitale committee report. The main cause of flooding in low-lying areas is heavy rains coinciding with high tides pushing sea water into the city’s drainage system. Hence, BMC says eliminating tidal effect on the city’s drainage network is crucial to reduce flooding.

In 2018, Amrita Bhattacharjee of the Aarey Conservation Group approached the Supreme Court with the plea that the area allocated for Metro Car shed in Aarey was rich in biodiversity and the catchment area of Mithi river and the Aarey forest needed to be protected.

“Concretisation of wetlands, mangroves, open spaces and waterbodies were drastically reducing water percolation capacity on ground, adding to excess flow of water to the storm water drainage system leading to floods,” she said, referring to her argument in the plea,  “Nature is the best architect and it creates its own checks and balances to protect a place from frequent natural calamities,” she says.

Holistic approach needed

Conservation architect Vikram Pawar of Water Environs which has initiated a RIVERs Consortium, observes: “City governance seems more about controlling the rivers than about understanding them and allowing its natural dynamic flow. There is no systematic thorough study done, no designed city master plan that seeks engagement with rivers; rivers are viewed more as a flood problem. The issue of concretisation of river edge embankments and their ecological restoration is not addressed at all. Natural systems demand holistic understanding; rivers should be viewed as watershed areas rather than subjected to piecemeal solution-oriented action, like pre-monsoon river dredging.”

Pawar suggests that efforts should be made to restore the rivers, allow public access to them and develop stakes in them, because “natural resources thrive as long as the culture of the land is connected to it”.

Officially, the BMC has called for tenders to rejuvenate the four rivers with Rs 130 crore earmarked only for Mithi river. The main task identified is to prevent sewage water from entering these rivers by building sewage lines and sewage treatment plants. While a four-phase plan has been chalked  out for Mithi, the other rivers are being considered for widening, improving quality of water, curbing pollutants and ensuring desilting access apart from beautification of river banks, the BMC announced in its budget. 

“The word nalla is derived from a Urdu word nal meaning umblical chord connecting mother and child,” said Jhaveri. “A nalla is nothing but a river tributary. Mumbai had many natural nallas or drains, which absorb rainwater and prevented flooding, but most of these are now either encroached or blocked by slums. The city also had many natural tanks like CP Tank, Gowalia Tank, Do Tanki and the Dhobi Ghat, most of which have been destroyed with concretisation. The city doesn’t need Sabarmati riverfront kind off beautification, we need rejuvenation. Each stream of every river should get its life back”. 

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