As Mumbai limped back to normalcy, a day after it was brought to its knees by torrential rain, the fear of the city flooding again remained imminent. While civic officials blamed the heavy rain for the waterlogging and disruption of life, the bigger and more pertinent issue — limited capacity of the storm water drains — went unaddressed.
The 285mm of rain in south Mumbai and 419.6mm of rain in the suburbs between 8.30am on Thursday and 8.30pm on Friday caused flooding at more than 200 locations, bringing local trains to a grinding halt, leading to traffic chaos and delaying flights.
The situation was better on Saturday, but not ideal, as the city again witnessed waterlogging in more than 20 areas, with rainfall of just 39.52mm in south Mumbai and 69.31mm in the suburbs. The trains were back on track, but running behind schedule. A man died owing to a tree fall, while a civic contractor’s labourer went missing while cleaning drains.
Had the downpour continued on Saturday, the city would have probably remained submerged for a second consecutive day.
Currently, the city’s storm water drains can handle 100mm of rainfall in 24 hours. Hence, another downpour, which can’t be ruled out as the monsoon peaks in July and August, will leave Mumbaiites under water again.
HT spoke to experts, all of whom unanimously blamed the limited capacity of the city’s storm water drains for the flooding. They also held the haphazard construction across the city responsible for putting additional burden on the existing civic infrastructure and blocking the natural flow of storm water.
“The carrying capacity of island city drains stands at 25mm of rain an hour and there is nothing we can do to increase it to 50mm an hour, other than depending on commissioning of pumping stations to drain storm water from area,” said LS Vhatkar, storm water drain engineer. This was the primary reason for the flooding in the low-lying areas of Parel, Dadar and Mumbai Central.
Even after the July 26 deluge of 2005, when the city received 994mm of rain in a day, the city and state government has done little to prevent flooding in Mumbai. The much-talked about Brihanmumbai Storm Water Drain Disposal System (BRIMSTOWAD) project, aimed at increasing the capacity of flushing out floor water, was commissioned in 2011, but is still not entirely functional. Out of the 58 projects under it, 28 have been completed, 27 are being worked upon and work on the remaining three is yet to begin.
“Administration’s actions are still dependent on the tidal system and there is no solution yet to solve waterlogging if heavy downpour is accompanied with high tide. Usually, the first big shower in the city clears all the drains, which are choked with plastic and garbage. Water will recede faster with the next shower,” said VK Pathak, former storm water drain engineer.
After facing flak for Friday’s chaos, the civic body is set to analyse and investigate the cause for the persistent waterlogging and failure of the two newly commissioned pumping stations. Civic chief Ajoy Mehta has asked officials to come up with an explanation and a detailed study to avoid a similar situation in the future.
“In the coming few weeks there is no major high tide of more than 4 metres and we should be able to tackle heavy rain. Our pumping stations, de-watering pumps are in working condition and even the level of Mithi River has receded,” said Sanjay Deshmukh, additional municipal commissioner.
Experts feel the flooding could have been avoided or at least minimised had the civic body properly cleaned the drains. “The intensity of rain was high, but with the two new pumping stations [at Lovegrove and Cleveland], the situation could have been much better at Dadar railway station, NM Joshi Marg and Mahalaxmi. The reason for flooding could have been choked drain entrances. The open drains in suburbs can to be cleaned and the administration can be questioned if they are not cleaned, but there is no attention to the underground drainage,” said Nandkumar Salvi, retired chief engineer roads, BMC.