Nagpur: The massive pre-monsoon exercise undertaken by the Nagpur Municipal Corporation (NMC) to clean more than 63,000 stormwater chambers and desilt nullahs has once again failed to prevent flooding, suggesting the problem runs far deeper than clogged drains.Sanitary workers involved in the recent desilting drive told TOI that while silt and garbage are removed every year, many drains suffer from serious engineering flaws. “The natural gradient required for rainwater to flow is missing along several stretches. In some places, the downstream chamber is actually at a higher level than the upstream one, slowing or even preventing the flow of water,” said a worker.The city’s rapid concretisation has further worsened the situation. Workers said several chambers, particularly along cement concrete (CC) roads, were clogged with hardened concrete and construction debris. Unlike silt or plastic, these materials are difficult to remove and substantially reduce the carrying capacity of the drainage network.Civic engineers said CC roads generate significantly higher surface runoff because rainwater can no longer percolate into the ground as it did through bituminous roads. “While road surfaces have been upgraded, the drainage network beneath them has remained largely unchanged,” an official said.The problem is compounded by inadequate drainage coverage. Nagpur has nearly 4,500km of roads, but only around 900km are served by stormwater drains. Earlier civic studies estimated that the existing network can efficiently handle only 42-44mm of rainfall per hour.According to NMC data, Mangalwari zone has the highest number of stormwater chambers at 15,101, followed by Nehru Nagar (12,351) and Gandhibagh (10,987). The remaining zones are Satranjipura (4,962), Hanuman Nagar (4,000), Laxmi Nagar (4,000), Ashi Nagar (3,875), Lakadganj (3,648), Dhantoli (2,300) and Dharampeth (1,900). Officials said all chambers are cleaned before every monsoon.However, experts said routine desilting alone can no longer address the city’s flooding problem. They argue that every new CC road project must be accompanied by a scientific redesign of adjoining stormwater drains, with proper gradients, higher carrying capacity and unobstructed outfalls. Without addressing these structural flaws, they warn, Nagpur will continue to experience flash floods despite spending crores annually on maintenance and road development.
