The Miracle of Kolkata's Wetlands

The wetlands are this Indian city’s free sewage works, a fertile aquatic garden and, most importantly, a flood defence – but they’re under threat from developers. One environmentalist is leading the resistance

The trees on the streets of Kolkata in January are dusty, like neglected pot plants. At traffic lights, salesmen offer feather dusters for drivers to wipe their grimy cars. Shrubs are planted on the central reservation of the city’s new flyovers, surrounded by the implausible boasts on signs proclaiming a “clean and green” city. But the most frequently recurring poster, above almost every street corner, appeals for investors to “Come to Bengal – Ride the Growth”.

Kolkata, a famously cultured city of 14.5 million people – once the second city of the British empire after London – is keen to catch up with Delhi, Mumbai, Chennai and Bangalore, the dynamic and rapidly modernising megacities of the fastest growing major economy in the world.

Kolkata is also a low-lying city, on average it is barely five metres above sea level, served by two major rivers and surrounded by waterways. Its unique wetlands to the east are under pressure from developers like never before, just when they might prove most useful. Hundreds of buildings, from luxury apartments to colleges to more modest homes, are going up in an area which is supposedly protected from development by law.

Faced by the rising sea levels and increased storminess brought on by climate change, cities all over the world – a World Bank study named Guangzhou, Miami, New York, New Orleans and Mumbai at risk of most costly damage – are having to rethink their relationship with flood defences, both natural and artificial. According to the World Bank, an optimistic forecast of just 20cm of sea level rise by 2050 would still make Kolkata the third most exposed city in the world to the risk of flooding.

Such projections no longer belong to a distant future. In November last year, similarly low-lying Chennai experienced cataclysmic floods, which caused the displacement of 1.8 million people. Twenty years ago, Chennai had 650 wetlands in and around the city. Today it has 27. Chennai’s super-powered growth came at the expense of the marshes that could act as an effective natural flood defence; without them, flood water had nowhere to go except cascade into smart new homes.

From the air, Kolkata’s tower blocks are golden in the hazy, smoggy sunshine. To the east, right up against the city sparkles a vast expanse of water: a patchwork of tiny flooded fields bordered by green embankments, ponds, channels and much larger lakes. Take the road to the East Kolkata Wetlands and you’re met by a stream of motorbikes towing two-wheeled trailers, piled high with vegetables and fat silvery carp and tilapia being lugged from the wetlands to city markets.

These waterways are a part-natural, part-human phenomenon and their miraculous character is explained by Dhrubajyoti Ghosh, a slight, bespectacled engineer-turned-ecologist-turned-anthropologist, who speaks English extremely softly and very correctly. Ghosh was asked in 1981 to conduct an investigation into what happened to Kolkata’s wastewater. The city produced a lot of sewage, didn’t have a treatment plant, but didn’t seem to have a pollution problem, either. The waste just sort of disappeared.

“The only English word that suits is serendipity,” says Ghosh, who is now 69, as we stand beside one of its ponds, with the ruins of what resembles a temple behind us. As a young man, he made the short commute from Kolkata to examine these lakes almost every day. He found that the pond water “was beautiful”. To diagnose what was occurring didn’t really require a degree in biology, he says, it was simply common sense. Wastewater is 95% water and 5% problem – bacteria.

Carried by long channels towards the ponds, effluent was broken down by UV rays from the sun. (Ironically, Kolkata’s middle classes pay for UV treatment of their tap water to make it drinkable.) This nutrient-rich water is channelled into ponds where algae and fish thrive. Sewage-grown fish may sound gross but Ghosh and others have found them to be safe; Kolkata’s sewage contains very low levels of heavy metals.

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• Environment
• Flood Management
• Wetlands