Water sources aplenty, but Chennai still thirsty

Though blessed with thousands of waterbodies and the annual average rainfall being reasonably good, it is ironic that Chennai is staring at yet another water shortage this year.

For a city that gets an average rainfall of nearly 140 cm, every summer is a struggle and water managers wait with fingers crossed for the Northeast monsoon to fill the reservoirs. The failure of monsoon to provide adequate rain just once, as in 2016, is enough to trap the city in a vicious water crisis.

And not just this. Chronic water shortage in a city surrounded by three major waterways — Cooum, Adyar and Buckingham canal (now mostly reduced to sewage carriers) — and thousands of waterbodies in neighbouring districts is ironic, and reflects the degenerating impact of urbanization over the city’s natural resources.

There are nearly 3,600 waterbodies in Tiruvallur, Chennai and Kancheepuram districts. If maintained properly, nearly 80 tmcft of water could have been stored during floods. The reservoirs that cater to the city have only a capacity to store 11 tmcft.

Citing the long process of creating new reservoir in Thervoy Kandigai Kannankottai, Tiruvallur district, Professor Janakarajan says it would need immense effort and a huge amount of funds to create new lakes.
They note that extreme weather resulting in floods or drought must be expected and used as an opportunity. Drought is the best time to desalt waterbodies.
Calling the major waterways city’s arteries, the long-standing dream to restore them may come true when the government and residents take a collective responsibility to arrest sewage flow into rivers.

Scarcity already

This year, the scramble for water has started much earlier than usual as Chennai district ended with a 57 % deficit in Northeast monsoon rain in 2016. While Chennai Metro water is planning to tap water from new resources, abandoned quarries or agricultural wells and smaller water bodies, residents are already thinking of sinking deeper bore wells. While it is deemed convenient to believe that Chennai is traditionally a rain-starved city, meteorologists note that the water scarcity is more of human-induced, as the annual rainfall has been less than 100 cm only on a few occasions since 1969.

Storage capacity

The city loses much of precious resource and reels under perpetual water crisis every summer as it lacks the capacity to store water. “The dry Poondi and Cholavaram reservoirs could be deepened to increase their capacity by 5-10 %. The tanks between the stretch of Chembarambakkam and Kaveripakkam could be improved and used for city supply,”

Grey water recycling?

Any attempt to restore the city waterways is futile, as has been proved, unless raw sewage flow is arrested and a comprehensive sewer network is in place. Though water from waterways cannot be used directly, they would be a good source of groundwater recharge, note experts.

“Chennai generates nearly 700 million litres of sewage daily. This could be recycled through decentralized treatment plants. It would work out cheaper at ₹28-30 per kilo litre than the desalinated water that costs ₹48 per kilo litre. The sludge could be converted into bio manure,” suggests Professor Janakarajan.

RWH more relevant

According to Sekar Raghavan, director, Rain Centre, it may sometimes become difficult to harness the entire volume of rainwater during monsoon as the water table fast reaches its saturation level. “We can harvest at least 80% of rainwater when the water table is low during summer. It is important to invest in rainwater harvesting according to soil conditions.


While a myopic agenda might well be the tool to address the immediate water needs of residents, Chennai, despite its vast wealth of natural resources, will remain a water-starved city unless long term and sustainable solutions are developed.