Mumbai’s drains have the capacity to carry only 25 mm water per hour, and siphons and other utility services create numerous obstructions in the larger drains, a report of the Comptroller and Auditor General of India (CAG) on the general and social sector has said. The report was tabled in the State Assembly on Tuesday.
Chief Minister Devendra Fadnavis told the House Mumbai received around 375 to 400 mm rainfall till Tuesday morning, terming the rainfall as unprecedented. The CAG report has also pointed out that there was a delay of six years in updating the Brihanmumbai storm water disposal system (Brimstowad) master plan.
The CAG said a major deficiency in the system to manage flood risk in Mumbai is the flat gradients, which result in drains being affected by tides and leave the system heavily silted.
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“Storm water drains discharge rainwater directly by gravity through outfalls, as floodgates have been provided in only three of the 45 outfalls. The outfalls discharge below mean sea level,” the report said.
It said poor workmanship and lack of attention to repairs when the drains are punctured by utility service providers, and poor structural conditions are a few other deficiencies.
The CAG also listed measures taken by the Brihanmumbai Municipal Corporation (BMC) to tackle flooding, which is a “chronic and recurrent problem in Mumbai during monsoon season from June to September, particularly when spells of intense rainfall coincide with high tide.”
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It said, “Disaster management unit of the BMC prepares flood preparedness guidelines every year. Ward-wise details of frequent flood-prone areas, open places, emergency assembly points, hospitals, food suppliers, fire stations, volunteers and NGOs were incorporated in the annual flood preparedness guidelines of the BMC,” it said.