In 1802, Madras was the epicentre of a project that eventually led to the discovery that Mount Everest was the tallest peak in the world. The Great Trigonometrical Survey of India was started from the St Thomas Mount in the city.
Exactly 202 years later, it was another man-made engineering feat, which ensured that large parts of Chennai were saved from the effects of the Boxing Day Tsunami. Hundreds died on Marina beach on that day, but it is said the energy of the giant waves dissipated by the Buckingham canal, that runs parallel to the Bay of Bengal coast, saving thousands living in the thickly populated areas just a few metres away.
The canal, which is about 800 km long from Kakinada in Andhra Pradesh to Chidambaram, and Kosasthalaiyar, Cooum and Adyar rivers that run through the city are a reminder of how Chennai is geographically endowed with waterbodies that have the capacity and capability to act as a natural protector against tsunamis, cyclones and carry excess flood water into the sea.
Along with several lakes created during the Pallava period, the city has hydrographic potential which balances the difficulty of drainage it faces due a flat terrain. But, these waterbodies today have been rendered as sewage carriers, negatively impacting public health as well. It's an irony, as around 170 years ago, the B canal was used to transport building construction material by the British. Even around 40 years ago, I have seen fishermen selling their catch of fresh prawns from the Adyar river on either side of the bridge, on my way to school. But now the water is too toxic for any aquatic life to exist.
The city is faced with unique quandaries- chronic water shortage, excess rain leading to flood and poor sewage treatment, translating into the death of its rivers.
Chennai’s problem of dying rivers is not unique; London’s Thames was also a sewer, but it was revitalised to some extent by creating embankments to divert sewage away from the river to a treatment plant down the estuary. Incidentally, London too is a flat city which gets copious amounts of rainfall and has a big river.
It is important that these waterbodies are revived as it would solve multiple problems; flood carrying capacity, public health and also transportation. The city already has a Public-Private-Partnership (PPP) model in the operation of crematoria, which can be replicated for revival of water bodies.
Chennai needs a multi-disciplinary approach to know where the excess flood water goes
This requires a comprehensive, multi-disciplinary approach and not ad-hocism. Firstly, the city requires a 3D map of its stormwater drains to know exactly where the excess flood water goes. Some drains are very old while some are demolished, and hence are not linked properly.
Secondly, the rivers and the canal cannot be sewage carriers. Floodwaters need to be routed to the sea, while the sewage must be sent to treatment plants. This will address public health concerns as well.
It is well known that Chennai is largely flat and the lack of a slope poses an engineering challenge for draining floodwater. The lakes on the periphery of the city need to be restored to improve retention capacity to meet the freshwater requirements of the growing city. River mouths can be widened to allow more flow to the sea.
Such ambitious plans are not new to the city, given that Chennai (Madras) was the first corporation in Asia. We must also remember that the city is prone to cyclones and needs to plan for one Tsunami every 100 years, given our experience with Poompuhar and Seven Pagodas.
As told to Siddharth Prabhakar
(The author is a film director-cum-cinematographer)