CHENNAI: The worst is over, but the city will remember 2015 as the year it was brought to its knees by the rain gods. Experts in urban planning say that Chennai must remember the lessons taught by the brief, yet pounding spell of rain.
Since the 1940s, the city had faced six such catastrophic rains which flooded the city — in 1943, 1976, 1985, 2002 and 2005. Each time the reason was cyclonic activity — which is difficult to predict. It is necessary for the city to be prepared for such times.
After each spell of rain, the state governments had formed committees to analyse how to make the city more resilient to such disasters. Each time, the reason for the disaster was the failure of the city’s major rivers — Adyar and Cooum — and other smaller canals to drain out the floodwater, says a senior official in CMDA, the city’s urban planning authority.
It was after the 1943 rains, which are said to be among the worst in Chennai’s history, that officials realised the need to keep the city’s major water bodies ready to handle floods. “A R Venkatachary’s report stressed the need to improve the Cooum River and the importance of removing sand bars that are naturally formed at the river’s mouth,” said the official. This recommendation is still followed and the earthmovers, one might notice while crossing Napiers’ bridge, are a result of this.
In 1980, the CMDA and Public Works Department came out with a report stressing the need to improve the drainage network so that North Chennai and Koyambedu don’t get inundated. But a city-based urban planner says that the recent inundation of Koyambedu makes it evident that many suggestions in the report were not implemented.
The 2005-floods were a wake up call and officials mooted several measures to prevent another incident of such large scale inundation in the city. “The situation has not improved. The reasons are three-fold. One, the waterways, reservoirs and tanks were not desilted. Two, flow channels and banks were obstructed by encroachments. Three, the trend of converting tanks and other water bodies into residential areas,” says another CMDA official.
The second master plan by the CMDA suggested turning such floods into opportunities by conserving water for a time of need. But 10 years later, no additional storage facility has been created.
- Cooum and Adyar rivers play a major role during floods. Surplus water from 75 and 450 lakes and tanks respectively gets drained through these rivers across northern districts of the state.
- The reduction in water holding capacity of the city’s surface is due to loss of green cover
- Uncontrolled urban sprawl and loss of natural drainage are also main causes for flooding
- Drainage channels have been blocked and urban lakes filled
- Canals degraded and polluted, heavily silted and narrowed
- Lack of planning and regulatory controls to prevent development in old tank beds
- Lack of unified flood control implementing agency that could integrate functions of the corporation, development authority, PWD, slum clearance board and housing Board
** The National Institute of Disaster Management