The three rivers are slow, gentle streams, meandering wildly through the plains, except when they carry large volumes of water during floods. In such rivers, the defined course includes a normally-dry area called the flood-banks, which takes surplus water during flooding events. For Adyar, these flood banks include many areas that went under water this time, such as Ekkaduthangal, Jafferkhanpet, Saidapet and Kotturpuram. In most of these places, the flood banks was systematically encroached upon over time and the river merely took its old course.
The South of the city, starting with Velachery and areas along the OMR do not have any rivers to take their load. What they do have instead is the Pallikaranai Marsh, which is a low-lying area that acted as a sink for flood-waters in the past. Historically, population density in these places has been quite low, partly because there’s no clear channel for water to drain. However, in recent decades, the Pallikaranai marsh has been systematically encroached upon, reducing it to less than a third of its original size, thereby reducing its capacity to absorb flood waters.
Encroachments
Here we must be a little careful — it is not that these areas built on water-bodies were un-planned or unauthorised, but that they were badly planned. Starting with T. Nagar which was promoted in the early 1900s as a scientifically planned township, almost all construction in these areas have approved layouts, CMDA authorised plans, completion certificates and every other piece of official paper from every official body you can name. Between the 70s and 90s, World Bank funded a scheme for housing called the Eri Scheme, which envisioned closing up several eris and building houses on top of them.
The Mogappair Eri Scheme area is one such place. Where they were not completely closed, these Eris were reduced severely in size, such as at Velachery and Ambattur.
The shanty-towns and slums that are most often called “encroachments” by officialdom are literally too small in number to matter.
These are often targeted after flooding, and indeed, are being targeted right now on the Saidapet banks of the Adyar and various places along the Cooum.
However, most of the areas built on waterbodies are neither slums nor unplanned construction. River View Road at Kotturpuram, on the flood-banks of the Adyar, is the up-market home of several of the wealthiest residents of the city. Similarly, Defence Colony, part of which is on the flood-banks of Adyar is another up-market residential area. Two major media houses have their offices right on the banks of the Adyar — they had to close shop during the rain.
Upon blaming the small-scale slums and shanty towns for flooding, our officialdom rejoices in “relocating” these people, typically to other areas built on other water-bodies.
Slum-dwellers uprooted from Mylapore were shifted into settlements such as Karpagambal Nagar built for them by the Slum Clearance Board on the Pallikaranai marsh.
The most stark case of officially sanctioned encroachment is the Porur Lake. Once the receiver of surplus water from Chembarambakkam, it would have protected areas to its west such as Valasaravakkam and Koyambedu. Now, it has been reduced to a quarter of its size, losing land to everything from slum clearance board settlements to educational institutions. The loss of this water-sink is another major reason that several areas have flooded.
A history of flooding
None of this is really new information. All of it can be found in official sources such as the CMDA Master Plan. Though the rains this time around have been the most severe in a long time, the actual amount of water released from the main reservoirs is hardly unprecedented. Roughly every 10 years, Chennai has received high rainfall.
In past events, a comparable amount of water has been released into the rivers. In 1976, 28000 cubic feet per second (cusecs) was released from Chembarambakkam into Adyar river.
In 1985, it was 63000. In 1996, the cumulative release from the three big reservoirs was 80000 cusecs — around the same as this year. Even the most recent event — 2005 - witnessed a then-record-breaking 40 cm of rainfall in a single day, with Cooum taking 20000 cusecs of flow and the Adyar, 40000.
We cannot claim that any of this is unprecedented. It is just that we have systematically ignored the risk and prioritised a real-estate boom over sustainable development and placed ourselves squarely in the danger zone for the last hundred years or so. It may not be possible to reset the clock to 1916, and to be sure, the city of that era was hardly an utopia. However, knowing all of this, and having witnessed the floods once every decade, it is time for us to insist that at least in the years going forward, the city’s growth is planned systematically and scientifically, and that standards are not diluted in the name of profit and short-term growth.
(concluded)
(The writer is an amateur historian and environmentalist, besides being an IT professional. He has been working on Cooum cultural mapping for past one and half years and associated with Exnora Naturalists Club since its foundation)
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