State govt to prepare drainage master plan to tackle rains above 100 mm per hour

Indian Express

3 days ago

To tackle the recurring flooding in city during heavy rain, the state government has turned its eye on enhancing the stormwater drainage capacity.
Mumbai's current stormwater drainage system is designed to handle rainfall up to 55 mm per hour. In the light of increasingly heavy rains, a new separate master plan is being created to handle rainfall exceeding 100 mm per hour.
The National Disaster Management Authority (NDMA) under the Union Ministry of Home Affairs will provide additional funds to support this initiative, said Minister for Cultural Affairs and Information Technology and Guardian Minister for Mumbai Suburbs, Ashish Shelar.
A meeting on flood situations and drainage measures in Mumbai was held on at Minister Shelar's chamber on Wednesday. BMC additional commissioners Vipin Sharma, Amit Saini, Abhijit Bangar and officials from departments concerned were present.
In 2017, Mumbai experienced 26 days of rains, and in 2024, 21 days. According to BMC studies, the city receives heavy rainfall averaging 16 to 20 days annually, with more than 100 mm of rain in an hour during some of these days. From 2014 to 2019, rainfall peaked at 131 mm/hour, and on May 19, it reached 182 mm/hour. On July 26, 2005, the city received nearly 1,000 mm of rainfall in 16 hours–averaging 139 mm/hour–which, combined with a high tide, led to severe flooding. In recent times too, rainfall exceeding 100 mm in an hour has become a frequent occurrence.
When such heavy rain coincides with high tide, proper drainage becomes impossible, forcing Mumbai to face flood-like situations.
Before the July 26, 2005, deluge, Mumbai's stormwater drains had a capacity of 25 mm/hour. Following the Chitale Committee's recommendations, this was upgraded to 55 mm/hour. However, with rainfall now frequently exceeding 100 mm/hour, further capacity enhancement is essential. The BMC plans to construct four new pumping stations, both small and big, as part of these efforts.
Currently, there are nine small pumping stations in Mumbai. Two more are to be set up at Maharashtra Nagar and Dharavi T-Junction. Also, there are six large pumping stations and two additional ones will be constructed at Mogra and Mahul. These new stations will help drain the water from flood-prone areas such as Kurla and Andheri.
Meanwhile, the National Disaster Management Authority (NDMA), under the Ministry of Home Affairs, has acknowledged the recurring flood crisis in Mumbai. In the first phase, Rs 500 crore has been allocated by Prime Minister Narendra Modi's government to the BMC to implement immediate flood-mitigation measures. The NDMA has also instructed the BMC to prepare a detailed action plan based on real-time assessments of the city's flood-prone areas. The draft plan prepared by the BMC is currently under review by an expert panel from IIT.
Flood-prone areas are being identified where advanced drainage infrastructure will be developed in those locations, designed to handle more than 100 mm of rain per hour. A detailed report will be prepared with assistance from IIT, and the preliminary estimate for this project is nearly Rs 5,000 crore. The NDMA is expected to provide substantial portion of this funding to implement this critical infrastructure upgrade.
Earlier, during his visit to Japan, Chief Minister Devendra Fadnavis had announced plans to adopt Japanese drainage technologies for Mumbai. Taking this into account, the BMC is integrating such innovations into the new master plan. Minister Shelar also instructed officials to prepare this comprehensive plan in coordination with authorities like Railways, Metro and MMRDA. He directed that the final report be completed within the next one month.