Mumbai grows..

After the 2005 deluge, the Brihanmumbai storm water disposal system (Brimstowad) project was put in place. The plan involved eight pumping stations and 58 projects to improve the city’s century-old pipelines. Fewer than half of these projects have been completed and Joshi said that even Brimstowad is not equipped to deal with the rainfall projections suggested by the data. “The existing drainage system should have been designed considering changes in rainfall patters based on future climate projections,” said Pankaj Joshi, director of Urban Design and Research Institute (UDRI).

Extreme rainfall and drainage are problems that are likely to become more severe in the near future. “The new Development Plan allows open space to be available on top of a podium,” said Joshi. “Essentially, these buildings are occupying the surface with construction and going underground to cover the entire plot area with multi-storied basements, taking away the permeability of the ground. Where will the water go?”

It doesn’t help that different government departments seem to be undercutting each other instead of working in tandem. “In a city like Mumbai, you have the railways, the BMC, the Mumbai Metropolitan Region Development Authority, the Mumbai Metro Rail Corporation, the Public Works Department, and all are at loggerheads about jurisdiction, which leads to carelessness on behalf of all parties involved. Each one believes the other will do the job,” said Nandkumar Salvi, former chief engineer of BMC’S SWD department.

In the BMC, for example, while the department of storm water drains (SWD) works hard to clean drains, nullahs and water laterals to maintain the drainage system, the department of building proposals sanctions projects without adhering to urban planning standards. Excessive and unchecked laying of utility in storm water drain culverts – such as telephone cables and gas pipelines – can choke drains, said Salvi. There is also the problem of ineffective solid waste management, which chokes storm water drains.

Researchers said bad urban planning has helped give rise to extreme rain that is not uniform across the city. “If there are a series of buildings with a road running in the middle, wind with all its moisture narrows down and follows the path of the road. With buildings acting as obstacles, the wind profile and flow gets disturbed, the atmosphere becomes unstable leading to more rainfall over a specific location,” said Subimal Ghosh of IIT-B’S civil engineering department. “We are in a situation when we won’t witness urban flooding just once or twice during the entire monsoon season, but every time it rains,” warned Mishra. Meanwhile, the India Meteorological Department (IMD) has forecast heavy to very heavy rain in parts of Mumbai and its suburbs till Friday.