Cover Story : Why Chennai Submerged?

1.    Incessant rains battered Chennai City for the past twenty days deluging the city with heavy waters. It is said that in 1918, the city witnessed a rainfall of 108.8 cm.  According to Skymet data, during the month of November, Chennai recorded a whopping 1218.6 mm of rain – three times its monthly rainfall. The normal rainfall figures for November stand at 407.4 mm. On the first day of December itself, Chennai recorded 374 mm and the forecast for the week says heavy rainfall will continue. Rainfall in Chennai in the last week of November was 347.3 which was 550% higher to the normal rainfall.
2.    Chennai is situated in a relatively plain terrain. The city is located at about 16 m above mean sea level, bounded by the Bay of Bengal on its northern side. Two major rivers, viz. Cooum and Adyar flow through the city and both do not have natural flow for several months of the year. These rivers were also found conveying flood discharge into sea during monsoon season. The Buckingham canal runs through the city from north to south parallel to the seacoast at about 1-2 km away from the coast. The canal links the two rivers. In addition, there are three major drains viz. Captain cotton canal, Otteri Nullah and Mambalam drain for discharge of storm water into watercourses. Otteri Nullah and Cotton Canal discharge into north Buckingham canal while Mamba-lam canal discharge into Adyar River. These waterways are flood carriers and have flow for about 2 months in a year in monsoon. The flow in these water courses during the non-monsoon period is from discharge of treated and untreated domestic waste water and trade effluent through several outfalls, leaving these water courses as storage basins of wastewater. This has created significant problem for flood protection system, storm water drainage network and associated public health and environmental problems inChennai city.
3.    As per records of Water Resources Department, the area of 19 major lakes has been shrunk from a total of 1130 hectares to nearly 645 hectares, reducing the storage capacity of watersheds. This obviously reduced increased the flood flows across the city.
4.    Encroachment along the banks of the rivers and non-enforcement of laws pertaining to protection of water bodies. Moreover, the Buckingham Canal is choked with silt and sewages. The waterways are polluted, contaminated and leading to unsanitary condition. According to a research survey, out of the 242 slums within the Chennai corporation area, 122 slums were classified as under objectionable slums. It means these slums are located/formed in land like river/canal margins, catchment of drains, greenbelts, etc., which do not confirm to the land use assigned in the approved master plan. Out of these 122 objectionable slums 33 slums were found along the road margins, 6 slums along the railway margins, 73 slums along waterways and 10 along the seashore. The total families in objectionable category of slums are about 41683. The ultimate result of all this is floods with water overflowing and inundating the city.

 5.    Much of Chennai’s recent urban expansion has been southwards. It is bound on the East by the Bay of Bengal, and Northwards, it touches the boundary of Andhra Pradesh. Thus, it is predominantly the South that provides space for the city to grow. In this context, the Old Mahabalipuram Road (OMR ) has been the seat of urban expansion, expanding the frontiers of the city towards the World Heritage site and tourist attraction of Mahabalipuram. Parallel to this is the East-Coast Road, that has also witnessed some development over recent years. South Chennai has since been growing as an IT corridor; in this process of expansion, the city has engulfed several fishing and agricultural villages and hamlets – of which Chennai has traditionally been an agglomeration – creating several ecological and environmental challenges that the current governance and administrative machinery is unable to cope with. Many of these problems have resulted from the growth of the city beyond its carrying capacity and the disconnect between urban and environmental planning.

In other words, flooding is caused due to combination of blockage in the channel, heavy rains, development along the stream channel and urbanisation near the watersheds.  
Chennai city population growth fuelled by prospects of higher incomes contributes to growth process. But city failed to deliver better quality of life. The urban poor lack adequate access to services like water supply, sewerage, education etc. The challenge of the city is the eco-restoration.
(With inputs from Smt Rama Devi, VSK Chennai)