URBAN FLOODING – A RECURRING PROBLEM

Trying to the BEST of its ability

There’s a colloquial saying in Kolkata that every time a frog wets its pants, the city goes under water. The same goes for Mumbai, India’s shining commercial capital. A few hours of rain and the shine is smudged by knee-deep water. Chennai, which did not experience large-scale waterlogging even a couple of decades ago, has drastically changed since the debilitating floods of 2015. Have you ever wondered why this happens every year? Whether it is Mumbai or Kolkata or Chennai or Delhi every city gets flooded during the monsoons. Even the relatively newer cities like Gurugram suffer the same ailment. To say that the municipal corporations of these cities are negligent and corrupt is all very easy but this may not be the sole reason. Is our town planning faulty? Do we at all take into consideration the water levels in nearby rivers and seas before planning cities? We surely do because all four megapolis cities that I mentioned are ancient cities and flooding is a recent phenomenon. So are we not maintaining our drainage systems? Are we not updating and improving them to meet the added load of the exploding population or the changing climate?

What is the answer to this menace?

Acrobatics in Gurugram roads

In my own city of Lucknow I have seen water bodies being land-filled to construct the large township of Gomtinagar. A significant part of this township gets submerged in monsoon every year and ironically this is the place which has the most expensive houses! It is the same story in Gurugram where people staying in flats costing 4 crores are incarcerated and waterlogged. In Bengaluru, a rapid, unplanned urban expansion has ensured that barely a handful of its interconnected lakes still survive, robbing the city of its capacity of natural storm water drainage. No wonder it gets flooded in the monsoons!

We are hoping that industrialists and entrepreneurs from overseas will invest in our economy, but when they see our premier cities inundated with overflowing rivers and an atmosphere of careless chaos everywhere, do you think their instincts tell them to invest in our country?

If it was blocked drains and potholes on roads we would have solved this problem by now. Don't you think we are missing something big? After all why would Jaipur, the capital of the desert state of Rajasthan get flooded of all the places?  Short bursts of intense rainfall are expected to become more common and our cities cannot cope with the downpour.  I feel we should find out the potential role of changing land use, land cover, including urbanization on heavy rainfall. Climate researchers have opined that Chennai flood was due to the warming up of the Bay of Bengal and El Nino effect. Rapid urbanization, deforestation all cause carbon release and greenhouse gas-induced climate change. Monsoons are getting heavier over cities where they are a menace but drought prone farmlands are also on the rise. Is there an available science to rearrange the monsoon and redistribute the rainfall for the benefit of both the deluged urbanites and the draught affected farmers?

Let us now see what we can do to avoid floods. One thing is for sure, it cannot be the responsibility of the government alone, we all have to pitch in our bit.

Respect the floodplains

We have to understand one thing clearly; our rivers are not static but dynamic. They may become a thin stream or even get interrupted during the dry season but will swell to their fullest glory during the monsoon. This extra land which it inundates is called its floodplain and no construction should be allowed in this zone. This land belongs to the river and it will reclaim it every monsoon. Essentially, what floodplains do is retain and absorb water, thereby shielding nearby towns from the effects of heavy rainfall.

Creating Sponge City

Creating a sponge city is an option. Rather than funneling rainwater away, a sponge city retains it for its own use, within its own boundaries. The uses include: irrigating gardens and urban farms, recharging depleted aquifers, replacing or replenishing the water used to flush toilets, and processing it so that it can be clean enough to use as drinking water. Wuhan is one of China's 16 sponge cities.

Green roof top gardens

Green roof top gardens by their very nature absorb rainwater and help to mitigate flooding. They are good for all: for the building owner, it’s a rainwater management tool; for the community, it reduces rainwater runoff; and for the environment, it prevents combined sewer overflow, neutralizes the acid rain effect and removes nitrogen pollution from the rainwater.

Preventing rainwater enter the sewer system

Our rainwater invariably runs into the sewer system. This is wrong. They should never mix. The separation enables the wastewater treatment plant to function properly, without it being overburdened by large quantities of rainwater. The rainwater can be used to recharge groundwater and aquifers.

De-clog the sewage system

Keeping the sewage system clean is obviously vital. They can clog up with waste, debris, plastic, sediment, tree roots and leaves.  The more traditional sewer pipes have a tendency to rust and corrode, compounding the problem. Plastic sewer pipe systems and Tegra manholes never corrode, and are easy to clean and inspect.

Replace concrete in pavements and sidewalks

Our love for concrete in pavements, sidewalks and even gardens is also killing our environment. Concrete is impermeable and these surfaces should be replaced with permeable materials such as grass and gardens.  This will allow the rainwater to drain into the soil. The process, known as infiltration, also serves to sustain the plant life. Otherwise this water will flow into the drains and flood the system.

Invest in climate warning systems

Properly conveying advance warnings of impending storms and floods today have not only given people the opportunity to be proactive in preventing damage to their property, it has saved lives too. Our space research has helped us in forecasting natural disasters including floods and loss of lives and prosperity is much less today. Odisha has perhaps maximally benefitted from them only because they have a responsive government.

Kolkata deluged.

Our town planning needs our urgent attention. The time of covering the wound with a BandAid is over. We cannot postpone the surgery any longer. We too should do our own bit. Whether it’s collecting rainwater or building a garden on top of our roofs, it’s imperative that we take the steps necessary to be part of the rainwater management solution. Complaining about the problem will not take us anywhere. We have to be a part of the solution.