A time series analysis of satellite imageries (1970s until 2015) reveal that Chennai, like many global cities, has been characterised by exponential, unbridled growth along the southern and western periphery, where most of the wetland complexes and cascades are located.
The city’s growth, while contributing to economic well -being, has maimed its ecological infrastructure. Around 65 per cent of the city’s lands which had the ability to hold, store, recharge and discharge water, have been lost. When we designate Chennai as a coastal city, it not only means that it is located on the fringes of a warm sea, the Bay of Bengal, but also highlights the fact that the city is vulnerable to climate vagaries and that the topography is flat, interspersed with large zones at altitudes below sea level. It also strongly indicates the need to address rainfall (and water) as a precious resource that needs to be handled using multiple approaches.
Evidently, protecting the wetlands of Chennai (whose numbers are still being debated upon) is one of the many options to protect its citizens from floods. More critical is the need to recognise that the hydrology of the city is a combination of natural to highly modified systems. And the hydrology of the city has not been characterised for its current connotation of growth, change in land use and land cover, demand of natural resources and so on.
It is well known that, in the past, wetlands that were deemed not useful were converted to what today stands as the modern heritage of Chennai – the Valluvar Kottam, the Chennai Mofussil Bus Terminus in Koyambedu, the Jawaharlal Nehru Stadium, the Panagal Building, etc., are examples of a rather long list for the city. Historically, the low-lying parts of the city were used for agriculture and inland fishing and the wetlands located within such parts were designed to facilitate overflow. What was historically an ecosystem service is today, a disaster. Water logged, marshy areas were part of the city’s ecological character and were the natural buffers to flooding.
Over the last few decades, each of these buffers has been systematically converted to human habitations. Even worse is the fact that most of these habitations were earmarked for communities being displaced by development projects. It is time to accept that much of the damage and loss that Chennai has experienced is irreversible. Limiting efforts to de-silting and cleaning wetlands or bounding the rivers with walls, however noble be the intention, does not serve the purpose of improving the city’s flood resilience. An integrated solution that is based on the principle of flood proofing the city needs to be found, and found soon.
— The writer is Managing Trustee, Care Earth Trust