When Mumbai’s municipal commissioner Ajoy Mehta briefed reporters on Friday about the heavy downpour that paralysed the city, he claimed that the city had “experienced unprecedented rainfall in the last 24 hours, more than that the city usually receives in 10 days”.

Mumbai, he said, had received 283 mm of rain in 24 hours. That was why several parts of India’s commercial capital had been plunged into darkness, educational institutions shut down, a grandfather and his five-year-old grandson electrocuted in Wadala in central Mumbai, and thousands of commuters had been left stranded as the local trains failed to run for most of the Friday.

Shiv Sena president Uddhav Thackery, whose party has controlled the municipal corporation for more than 20 years, went a step further to explain the incompetence of Asia’s richest civic body. (It has an annual budget of Rs 33,514.15 crore, more than the state budgets of Goa, Himachal Pradesh, Uttarakhand and some other states.) His strategy was to blame the weather Gods. “I won't hold the BMC [Brihanmumbai Municipal Corporation] responsible,” Thackeray said. “Situation was like a cloud burst. This was a huge problem.”

Here come the experts

The cloud burst to which he was referring occurred exactly a decade ago on July 26, 2005, when Mumbai received 944 mm of rain in 24 hours (compared to Friday’s 283 mm), killing 914 people. In the wake of this tragedy, the Maharashtra government and the Mumbai Metropolitan Region Development Authority, which oversee plans for the 4,354 sq km region, commissioned several impressively titled studies.

Many of them were focussed on the Mithi river that runs through the Western suburbs, which overflowed its banks that terrible July afternoon. The studies included the “1-D Mathematical Model & Desk Studies for Mitigating Floods of the Mithi River”, a “Baseline Socio-Economic Survey” for the entire width of Mithi River and a “Fact-Finding Committee” to understand the reasons for the July 26 disaster and prepare an action plan to mitigate future floods.

Even before the 2005 deluge, the state government had displayed a penchant for commissioning studies. Many of them had warned of serious consequences if urgent steps were not taken soon. Among them were the “Nathu Committee Report” of 1975, the oft-cited "Brihanmumbai Storm Water Drainage Project (or BRIMSTOWAD)  Report" of 1993, and the "Mithi River Water Pollution and Recommendation for its Control" by Klean Environment Consultants in 2004.

Armed with so many reports and recommendations, it would be natural to expect that by now, 40 years after the first such report, the municipal corporation would be in a foolproof position to handle any unprecedented rainfall. However, the chaos that was unleashed on Friday speaks volumes about the seriousness with which both the municipal corporations and the politicians who run it consider the weather events that they insist on defining as unprecedented and as acts of God.

An enormous challenge

One of the main problems is that the plans fail to acknowledge that the situation is only going to get much worse. After the 2005 floods, many experts were emphatic that the unusually intense rainfall was linked to the changing climate. Among them was the India Meteorological Department’s regional team in Mumbai. In a 2009 report titled “Environmental Degradation, Disasters and Climate Change” that analysed 100 years of weather data from 1901, the team found after 2001, the rainfall over Mumbai had increased. The team warned of heavier rains and more frequent thunderstorms.

Several other scientific reports that are warning against climate change- induced impacts in Mumbai. In 2007, a study conducted by AS Unnikrishnan and D Shankar of Goa-based National Institute of Oceanography based in 113 years of data, said that Mumbai is witnessing a sea-level-rise of 0.77 mm per year.

UK-based Maplecroft’s Climate Change and Environmental Risk Atlas 2013 has ranked Mumbai eighth in the global list of total 50 cities (chosen for their current and future importance to global business) that face a range of risks due to climate change. It lists Mumbai in the “high risk” category in the climate change vulnerability index.

The costs of climate change will not be cheap.  One study calculated that material damage to low-lying areas due to extreme weather events will be Rs 6,413 crore over the period 2005-2050. Mortality costs due will be Rs 3,050 cror, building-foundation damages due to sea-level rise was put at Rs 1,501,725 crore and and tourism loss at Rs 1,963,500 crore.

Building resilience

Strengthening city’s infrastructure to resist flood risks and adapt to climate change is imperative, especially when the city’s gravity drainage system was designed way in the 1920s. Its storm water drainage was designed for a rainfall of 25 mm per hour and a run-off coefficient of only 0.5. (The run-off coefficient refers to the percentage of rainfall that appears as storm water run-off from a surface.) However, over the century, with major changes in land-use patterns the run-off co-efficient has increased to 1.

The 1993 BRIMSTOWAD report had recommended increasing the storm water drainage capacity to 50 mm per hour and coefficient of run-off to 1. Twenty-two years later, the corporation is still working on it. Had this work completed, Mumbaikars would have been spared Friday’s chaos, which occurred with hourly rainfall of 34.8 mm.

Apart from overhauling the drainage system of Mumbai, the BRIMSTOWAD report had recommended the construction of eight pumping stations to expel water into the sea in areas where drains cannot be widened. Of these eight stations, only two have been completed. After years of delay, the other two pumping stations – Love Grove in Worli and Cleveland Bunder in Reay Road – had trial runs only last month. The Rs 102-crore Cleveland pumping station was finally inaugurated Wednesday, only to develop a fault and stop functioning during Friday’s deluge.

Drain inspector's report

The municipal corporation also claims to be the 340 km network of major nullahs (which are 3 m wide) and the 200 km network of minor nullahs (which are 1.5 m wide). Roadside gutters, which run 2,000 km, have also been desilted. Alongside, the infamous Mithi river has also been dredged. In addition, rain gauges have been installed at 26 fire stations across Mumbai that transmit data to the municipality’s central control room every one hour. The Municipal Corporation of Greater Mumbai claims to be the only corporation in India to have undertaken an aerial survey of the city to prepare detailed contour maps. These are supposed to help predict the extent and intensity of area-wise flooding during heavy rainfall.

However, there is a mismatch between the municipality’s tall claims and ground reality. This was pointed out in the Comptroller and Auditor General’s audit report for 2013, which has blamed the corporation for the delays and cost escalation in the implementation of BRIMSTOWAD report. It said that as of September 2013, the actual expenditure incurred on the project was Rs 1,764.55 crore, overshooting the estimated cost of Rs 1,175.72 crore. However, only 27.6% of the work has been completed. It is estimated that the project will cost Rs 2,708.89 crore more to complete.

“Due to delay in implementation of the project, flooding in Mumbai city and suburban areas continues,” the report noted balefully.

It’s clear that Mumbai faces growing threats from climate change and extreme weather events. Rather than blaming the unprecedented rainfall that is becoming a regular weather phenomenon, it’s time for the Mumbai’s bureaucrats and politicians to their act together and perform. The functioning of India’s financial capital is at stake.

Nidhi Jamwal is a freelance journalist from Mumbai who reports on the environment. Her Twitter handle is @JamwalNidhi.