‘Despite efforts, Mumbai will never be flood-free’
MUMBAI: The problem of waterlogging is going to stay with Mumbai and the city is never going to become flood-free, despite several measures being taken by the civic body, said P Velrasu, additional municipal commissioner (projects), Brihanmumbai Municipal Corporation (BMC). In an interview with Hindustan Times, he also explained how climate change is affecting the rainfall pattern and why some of the big-ticket construction projects like coastal road have no links with flooding in the city.
You have been saying that rainfall above 200 mm in a short duration can cause unpredictable problems in Mumbai. Despite the BMC’S efforts, will the city ever become flood-free?
The entire city is situated on reclaimed land and most of the places, including some of the major flood-prone areas, are below the main sea level (MSL). In the event of heavy rain, some parts will get flooded because our system won’t be able to prevent it, and this is going to be a regular feature especially when extreme climatic events have become common. So, all we can do is to prepare our system at the maximum level because no city in the world can tackle 200mm or 250 mm rain per hour without having water stagnation in some areas.
What should be your advice to citizens during extreme weather
Whenever we anticipate an adverse weather condition, we relay weather updates through bulletins every three hours. These forecast details are shared by the Indian Meteorological Department. Hence, in case of extreme events, people should avoid stepping out unless it is absolutely necessary.
Official says a change in mindset will help address the problem of floating garbage, a contingency plan ready to tackle flash flood
This is a challenge the civic body faces every year. Many people say we have not properly done the desilting of the nullahs. We remove solid waste, plastics, and polythene, but within a week’s time, such materials resurface. We have also explored possibilities to come up with alternatives. But to my surprise, I was told that even when dustbins were made available within a few metre, some people would still prefer throwing garbage in drains because it was at a shorter distance. So, it requires a change in mindset.
Our assessment of roads after a pre-monsoon audit says there are uneven spots showing patchwork repairs, loose gravel. Our experts told us that in places where maintenance work was not properly carried out, water could seep in, which might lead to the formation of potholes.
If a road is constructed using asphalt, then the life of the asphalt depends on how waterproof it is. You may execute an asphalt road excellently but if you leave the side shoulders of the road open, then water may enter from there and start eroding it. In many cases, due to the urgency of work, restoration and maintenance are not properly carried out. As a result, the surface of the road doesn’t become 100% waterproof and causes erosion which subsequently leads to the formation of potholes. Practically, this problem could be resolved in the long run by building cement and concrete roads. Of the 2,038 km of roads in Mumbai, we have already concretised 1,000 km.
Last year, the water supply in the city was affected after floodwater entered the filtration plants in Bhandup. How are we looking at these problems now?
A contingency plan has been prepared. Last year, there was a flash flood in the adjacent Sanjay Gandhi National Park (SGNP) due to which water entered the Bhandup filtration complex. We don’t have control over the SGNP. Therefore, as a precautionary measure, we have constructed a protection wall alongside the filtration complex and we have created a drainage system and pumping mechanism.
You have said in the past that most of the electrical substations and transformers are at the ground level which may lead to power outages if the areas where these substations are located get waterlogged. How do we plan to tackle this situation in the long run?
The authorities need to map the locations that house utility networks like electric substations with reference to the MSL. In the meantime, these spots need to be elevated by at least four metre above the MSL.
Several residents and civic activists have linked the waterlogging in south Mumbai with the coastal road project. Even some environmentalists and urban planners have said these big-ticket projects have intensified flooding in the island city.
There is no scientific basis for this argument. Back in 2020, there was flooding and stagnation of water in south Mumbai and during that time the intensity of rain was very high unlike previous years. More than 120mm rainfall was reported then and several parts of south Mumbai including Vidhan Bhavan went under water. We have already deployed our team all along coastal road to check that the drainage system is not affected and there are no blockages. In 2020, the adverse flooding in south Mumbai was caused by the high intensity of rain, and there is no direct relation between the coastal road project and flooding.
How well do you think Mumbai is prepared for monsoon this time?
In the last two years, the BMC has identified several flooding spots and has steadily worked on them. We are also experimenting unique projects like water-holding tanks. But we have to keep it in mind that while on one hand these efforts are bearing fruit, on the other, the intensity of rain and extreme climate events are also increasing.