A flawed concept

Urban centres should move from the concept of storm water drains to ‘storm water harvesting’

March 17, 2019 12:15 am | Updated 12:15 am IST

Many roads in Chennai are currently being dug up to build storm water drains, probably by way of being prepared for the next rainy season. This set me thinking about the very concept of storm water drains. Storm water is another name for rain water and drain is a means to clear accumulated water. After settling in Chennai about 60 years ago, I have seen many aspects and features of the rainy season. One common feature over the years has been that the city is always caught unawares when the rain comes and it triggers a spurt of activity that continues even after the season has passed.

First of all, I think there is something seriously wrong with the very concept of storm water drainage. What we need instead is storm water harvesting. The slogan of rainwater harvesting, which was initiated some years ago, has caught on among the public and rainwater harvesting is being implemented by most residents. But this is restricted to saving the water that falls on one’s own property. By all accounts this has been a success and has gone a long way towards maintaining the level and the quality of groundwater. Let us turn our attention to the rain that falls on the roads and open spaces. Even after a short spell of rain, the city roads and surroundings get flooded and complaints from the public start pouring in. The roads become dry only slowly due to the inadequacy of the drainage system. This is what the city administration is trying to remedy.

That is all very good. Now to come to what I think is wrong planning. It is my understanding that the water that flows through the now-improved drains empty out quickly into the rivers of the sea. The water can be caught and harvested in several ways. One of these is to let this water flow into and collect in ponds, tanks (as in temple tanks) or lakes, natural ones where such are available, or artificially created for this specific purpose. In the not-too-distant past the countryside and suburbs of our towns were dotted by such waterbodies. With the inexorable onslaught of urbanisation and the demand for real estate for residential and other uses, these have largely been filled up, leading to flooding.

Where such waterbodies cannot be created or sustained owing to space constraints, the tried and proven methods of rainwater harvesting, namely, creation of soak-pits at frequent intervals, should be implemented. This will help maintain the level of the water table, which is rapidly going down due to the pumping out of groundwater.

Going through data available in the public domain, one is struck by the fact that even though the total rainfall varies year to year, extreme conditions of drought have rarely been recorded. The city does get a reasonable amount of rain every year. Where we go wrong seems to be ln our approach to water management.

Practices in other countries are worth studying. Take two extremes as examples in terms of size. Singapore, a very small country, depends largely on rain for its water needs. They conserve all the rainwater that falls on the small extent of land. Yes, they use storm water drainage, but the water, instead of being drained into the surrounding ocean, goes to processing plants.

On the other extreme of land size is the United States. The country has plenty of rainfall and plenty of rivers and freshwater lakes. Construction activities do go on at a rapid pace in most places. For every new residential complex, in order to get approval it is mandatory that the developer creates a waterbody, pond or lake, in the subdivision, which can be used for recreational purposes.

We should, as a first measure, change the expression, ‘storm water drain’, to ‘storm water harvesting’. What is in a name, you might ask. I say, a lot. The correct expression or slogan will go a long way to mould public opinion and thereby the policies of civic bodies.


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