Mumbai grows, more rain woes
A rapidly expanding city, Metro construction, more highrise buildings leave little room for rainwater to flow off streets
MUMBAI: On June 21, the Brihanmumbai Municipal Corporation (BMC) assured the Bombay high court that it was prepared to “tackle all natural calamities” this monsoon. It had mapped 186 flooding spots, installed water suction pumps in areas prone to waterlogging and installed special safety grilles on manholes. On paper, the civic body was ready for the annual rainy season – until the torrential rainfall of July struck the city. On Tuesday, Mumbai surpassed more than 65% of its average annual rainfall in just the first month of the monsoon and the city’s infrastructure has struggled to cope with the downpour.
In addition to places like Hindmata, which are low-lying and known to be prone to flooding, Tuesday saw waterlogging in Goregaon, Chembur and Mankhurd. In Vasai, the National Disaster Response Force (NDRF) had to be deployed. Stretches of the local train network’s tracks were submerged. Flights were delayed and traffic was disrupted all over the city. Pockmarked by Metro and Monorail construction sites as well as road works and other projects, Mumbai is drowning under haphazard urban planning and changing weather patterns. The concretisation of the city is considered to be a sign of development by many, but experts warn that these projects are significantly lowering Mumbai’s ability to drain rainwater.
City-based architect Roshni Udyavar Yehuda said the rapid concretisation meant shrinking surface area in Mumbai, which makes the city becoming more vulnerable to waterlogging. “In new projects, there is next to no open space that will allow water to seep into the ground,” said Yehuda.
Studies conducted by the Indian Institutes of Technology at Mumbai (IIT-B) and Gandhinagar (IIT-GN) suggest that considering the rainfall projections for Mumbai, the city will have to increase the carrying capacity of its storm water drains. “There’s been rapid urban growth, but the drainage system is based on past rainfall records and does not take into account the changing nature and characteristic of rainfall that has led to an underestimation of the old design,” said Vimal Mishra, associate professor at IIT-GN.
Meteorological data suggests Mumbai is likely to face more intense flooding in the near future. In 2017, the Indian Institute of Tropical Meteorology in Pune found that across India, there had been a threefold rise in rainfall extremes during the monsoon over the past three years. IIT-B studied rainfall data for Colaba (1901-2008) and Santacruz (1951-2008) and found there was now one per cent chance that Colaba could record 164mm of rain in an hour.
One per cent may sound like a low probability, but on July 26, 2005, Mumbai witnessed 190mm of rainfall per hour.
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