Mumbai: After sudden flooding occurred in the island city during the heavy downpour on May 26, the BMC has decided to widen the existing stormwater drains in the affected areas.
As part of this upgrade, the drainage infrastructure will be enhanced to accommodate up to 120 mm of rainfall per hour. Currently, the system has the capacity to handle only 55 mm of rainwater per hour, which proved inadequate during the recent deluge.
This year, the early arrival of the monsoon in Mumbai and its suburbs was marked by a torrential downpour of nearly 200 mm within just 12 hours. The intensity of the rain exposed serious shortcomings in the BMC's monsoon preparedness, with 80 new waterlogged spots identified in the island city alone.
Civic officials admitted that the sudden flooding was primarily due to the inadequacy of the existing stormwater drains, which were unable to handle such a large volume of rainwater in a short time.
A senior civic official said, "The rainfall pattern has changed in recent years, leading to situations where the city receives a large volume of rain within a very short period. Earlier, the major drains were designed to handle around 25 mm of rainfall per hour. Following the 2006 deluge, a decision was made to widen these drains to accommodate up to 55 mm of rainwater per hour. However, with the increasing intensity of rainfall events, we now believe that the existing major drains need to be further widened to handle up to 120 mm of rainfall per hour.”
Accordingly, the BMC will appoint an expert agency to carry out a detailed survey of the stormwater drains in the island city to assess the extent to which each drain needs to be widened.
Simultaneously, assistant municipal commissioners from all 24 administrative wards will be instructed to submit detailed observations and assessments of the drainage systems in their respective jurisdictions.
As per the official, based on these reports, localised interventions will be implemented to improve water flow through the drains and prevent overflows during intense, short-duration rainfall events. Mumbai has an extensive and complex drainage network, comprising 261.52 km of major nullahs and 411.56 km of minor nullahs.
