And the city floods again…

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Updated: November 26, 2015 1:20:57 PM

Recurrent flooding shows that Chennai is turning into a man-made urban disaster.

Recurrent flooding shows that Chennai is turning into a man-made urban disaster.Recurrent flooding shows that Chennai is turning into a man-made urban disaster.

Chennai is no stranger to heavy rains. The city is situated on the high-energy east coast, and has often faced cyclones and heavy rains due to low pressures in the Bay of Bengal. But, over the years, Chennai has not been able to withstand the downpour, this year being particularly bad. The infrastructure crumbles with great regularity.

The 30-year-old Citizen Consumer and Civic Action Group (CAG), Chennai, blames poor planning and the near lack of enforcement of any planning rule. This has resulted in rampant building violations, such as encroaching roads and pavements, illegal connections of sewerage lines to storm water drains, and construction on ponds, lakes, marshes and other natural catchment areas. Water bodies are generally viewed as sources of irrigation and drinking water, and not environmental assets. As a result, lakes and rivers which do not provide water for irrigation or drinking are often reclaimed as wastelands.

MRC Nagar, a commercial and residential complex, has been built in the Adyar estuary. The MRTS has been built almost wholly on the Buckingham Canal. Several government planned colonies were all built on drained tank beds, as also is a vast part of the industrial area in Padi, which came up on what was the Villivakkam Tank. Many other major projects are examples of blatant encroachments on waterways and water bodies that used to drain the city during floods.

A study done when the Second Master Plan was being finalised a few years ago revealed that between the 1970s and the 1990s, the area of 19 major lakes and tanks in the city had shrunk from 1,130 hectares to just 645 hectares. The city’s storage capacity has been reduced by more than 50%. With greater awareness today, residents and environment conservationists are keeping a sharp watch on encroachment along lakes and tanks. Some lost water bodies have even been recovered, in spite of opposition from vested interests. But all this will be too little and too late unless the administration wakes up to curb the takeover of water bodies at the very start.

Chennai lacks adequate drainage network. It is a flat city with no slopes for water to drain into the sea. There have been several good schemes to improve the system by going in for larger and stronger drains. Despite several crores of rupees being allocated in the Chennai Corporation budget and the JNNURM for the construction of storm water drains (SWD), only a fraction of Chennai’s roads have these. The drains coming up very close to the city slums invariably get stalled. Vote bank politics prevented the project’s progress a few years ago because of widespread protest from slum dwellers. These projects were awarded to the lowest bidders. Many of them were inexperienced and incompetent, and the constructions were abandoned half way through. There is a lack of data on the network and its quality.

There are a multitude of agencies in charge of Chennai roads and drain network—Chennai Corporation, Chennai Metropolitan Water Supply and Sewerage Board, Chennai Traffic Police, Highways Department, and several public and private utility and telecommunication companies. All regularly dig roads to lay infrastructure and the schedules are not coordinated. There is a problem with alignment of road cambers (the convexity or curvature of the road to avoid staying of water) with SWD inlets, poor garbage collection which results in blocked inlets, and often an intersection of the sewage and SWD networks.

Last year, the CAG worked with Chennai Corporation to map city’s water stagnation locations following heavy rains in October. Even though Chennai receives an average rainfall of 129 cm—well above national average—encroachment allows only 5% of this water to percolate into the ground. Further, the city has exploited 80% of its ground water, and experts fear any more extraction could lead to salt water ingression (movement of salt water into fresh water reservoirs due to pressure gradient).

The roads, without fail, collapse at the first monsoon rains. When repairs take place, the asphalt is laid on top of the existing black-top. So the road gets higher. In developed countries, road milling is done, which is the process of removing at least part of the surface of a paved area so that the road remains at the same level. The government is reluctant to do milling here as it is an expensive process. Disposing off the milled substance is also expensive. To do this, one has to invest in machinery, which is very costly. In countries where milling is carried out, the material is recycled, and 60% of the tar, which is used to build roads, can be extracted from the recycled material. The city is also fast running out of stone and sand. People are going further and further away to bring these into the city. This makes overall road construction a very expensive proposition.

All existing lakes have to be deepened. This has to be done during the long dry season. It will increase storage levels. With concrete structures erupting every other day, stricter enforcement of rainwater harvesting, which has become lax, becomes important.

It’s not just Chennai and its suburbs that are affected by poor planning, nearby towns like Ponneri—which is slotted to be a smart city—have also been inundated. The CAG says to reverse this flooding which is getting worse every year, it will require more than just good infrastructure. It will require good data and maps, sound planning practices, and enhanced accountability of public agencies that are responsible for the way the city is shaped.

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