Chennai's floods

India must brace for more cloudbursts that stress its cities

Record amounts of rain have hit Chennai and other parts of northern Tamil Nadu. A low-pressure area over the Bay of Bengal has meant that Tamil Nadu, coastal Andhra Pradesh and parts of Sri Lanka have been battered by rainfall - Chennai received 23.5 centimetres of rain between 8 am, Sunday and 8 pm, Monday, the most in 30 years. The city couldn't handle this; large parts of it have been flooded for days, and at least 10,000 people have had to be evacuated from their homes. About 1,000 of those were rescued by a battalion of the National Disaster Relief Force; the Madras Regiment of the army was also called out, as was the navy. Even the air force said it had rescued 22 people, airlifting them out of difficult situations, using helicopters flying sorties out of the Tambaram Air Force Station. In spite of that, at least 70 casualties have been reported in the city and other parts of the state.

There is considerable anger against the state government. The chief minister, J Jayalalithaa, was elected to the Assembly from a city constituency, R K Nagar. Visiting the area after the rains hit, she pleaded for patience, saying that the flooding was "inevitable". Given that "the rain that was meant to be spread out over the monsoon months has poured in just a few days... No precautionary measures would have managed to prevent waterlogging and damage," she said. However, she did announce a Rs 500-crore relief package, the opening of 50 additional state-run grocery stores to ensure the availability of food, and various other measures. Ms Jayalalithaa has a point; but the Opposition has pointed to the fact that recently-installed, expensive storm drains were supposed to deal with problems of this kind but signally failed to deliver. The Indian Express reported that, sometime in July 2014, a Chennai Metropolitan Development Authority engineer wrote a confession letter to his superior detailing how a multi-crore storm water drain project at Koyambedu was executed without concrete reinforcements or cement, but instead with "quarry dust". Certainly, Ms Jayalalithaa's image as a formidable administrator has taken a hit.

The lessons of Chennai's floods, however, go far beyond state politics. In fact, the combination of circumstances reveals how unprepared Indian cities are for the extreme weather events that will accompany global warming. Cloudbursts of the sort Chennai suffered are increasingly becoming common. They will put urban drainage under stress; and this is especially true of those cities that have been built on swampy or marshy land, such as Chennai or Kolkata, but in which rampant overbuilding has destroyed the natural drainage and watercourses. India must prepare better for such cloudbursts. The National Disaster Management Authority, in particular, cannot just coordinate responses to disasters; if it is to exist at all, it should at least also try to get ahead of the curve and anticipate problems. It must begin to build scenarios for future such events so that state governments have templates on which to try and restructure towns.