CHENNAI: Rivers, coastal floodplains, wetlands, natural flood barriers, streams, canals and backwaters are the guardians of Chennai in times of floods. However, all of them succumbed to the mighty 1,200 mm rainfall that the city recorded in November 2015, right before the floods that drowned Chennai.
The Parliamentary Committee of Home Affairs in its report for the reason of Chennai floods in 2015 said that encroachment of lakes and river beds, faulty town planning and drainage system were the major causes.
The report further pointed out that encroachments had reduced the carrying capacity of Adyar, Cooum and Kosasthalaiyar rivers — the three natural flood barriers of the city, gushing down water to the sea. More importantly, it held the Chennai Corporation and CMDA accountable for the disaster.
Has there been a change?
After the city faced one of its worst-ever water crisis this summer, with an almost 200-day dry spell, the June and July rains were a welcome respite. The Indian Meteorological Department data recorded 221 mm rainfall between June 1 and June 24. However, visibly, many localities in the city drowned even with light showers in July.
But the civic body doesn’t seem to have learned the lessons well. Stormwater drains and canals are choked with garbage, the three rivers continue to be a waste disposal site, carriers of sewage, and industrial and commercial establishments continue to expand in ecologically sensitive zones, with the Kattupalli Port expansion, being a recent one. Express spent time along the banks of Adyar and Cooum to identify the places where garbage is still seen in large scale. Cooum river along Flagstaff Road (Parrys), Egmore, Nungambakkam, and Aminjikarai continue to bear the brunt of the city’s garbage including plastic and other non-biodegradable waste.
Water Resources Department (WRD) officials say works were on to clean garbage from Cooum near Flagstaff Road while encroachments between Napier bridge and Chetpet were cleared earlier.
However, the sewage outflow in these rivers have not been stopped as the `36-crore modular sewage treatment plant project along the Cooum river has been marred by red-tapism, and is yet to take off.
Though the walls on Thriuvika Bridge block the view of Adyar river, garbage lying along the bunds is a sight one can’t ignore. Similarly, the riverbank along with the localities near West Tambaram and Mudichur, which faced the worst floods in 2015, continues to be a garbage dumping hub. Encroachments along the riverbank in areas around Mudichur, not far from Chembarambakkam, have not been removed.
Thousands of crores have been repeatedly allocated by the government, over the past decade, for river restoration work under Chennai Rivers Restoration Trust and Cooum Restoration Trust. But for removing encroachments in areas around Egmore, Chetpet, and Chindradrimet, not much has changed. Experts believe the continuous discharge of sewage and garbage disposal has killed the life of these rivers. “The oxygen levels present in the waterbody should at least be three percent. It is not so in these rivers. Its ecology has already died,” says former professor and HOD of Geography, University of Madras, N Sivagnanam, who has been into research for four decades.
“Before removing garbage from the river, the government has to identify a place to dispose of the trash. Here, they remove the garbage, put it on the bund and forget about it. It again goes back to the river, raising the water levels during floods,” he says.
The case of Kosasthalaiyar
Unlike Adyar and Cooum rivers which directly flow into the sea, Kosasthalaiyar holds water in the catchment areas of the creek before discharging. Over the years, industrial expansion along its catchment areas have gobbled up the size of the 8,000-acre river by at least 1,500 acres.
Also, the accumulation of sludge, and with no dredging taking place, the depth of the river has shrunk to two feet from what fishermen claim was 14 feet about a century ago. “Only the main channels which have silted up are dredged. But, the entire backwater has to be looked upon,” says Pooja Kumar of Save Ennore Creek campaign.
Two months back, the WRD took a step by building a protection wall in Kattukuppam village for 90 metres along the river at Rs 16 lakh. The fishermen had questioned why a sewage wall was being built instead of bringing the river to its original flow by dredging and plugging down chemical effluents and sewage.
“A flood prevention wall will not prevent flooding. Kosasthalaiyar is a macro-drainage system and it is completely misunderstood,” says Pooja.
Pointing to recent developments on industries coming up in ecologically sensitive zones, she says salt pans and floodplains are being looked as real estate lands and new establishments are constantly coming up. “Catchment areas are being compromised at a very high speed,” she says.
Garbage blocking water flow in stormwater drains is another major cause for the city going underwater, even after a day’s rain. S Janakarajan, an expert on disaster risk reduction and former professor of Madras Institute of Development Studies, says that the stormwater drains (SWD) are unscientifically built without studying the elevation. “There must be a plan on where to construct the SWD. In most places, they (civic body) do not know where to take the SWD, and they end up linking it to sewage,” he points out.
“Secondly, SWDs lack maintenance. They just construct and leave it without even knowing whether it can carry ‘stormwater’ or not,” he says.
The story is the same with canals. Express visited several canals in the city such as the ones at Thiruneermalai, Virugambakkam, Buckingham (near IOC and Thiruvottriyur), Vyasarpadi, and Kodungaiyur. All of them are choked with heavy garbage while some like the one in Thiruneermalai have turned into a garbage bed, obstructing any water flow.
Janakarajan says, surplus water flows through canals and it reaches the lakes, which are macro-drains. “However now, tanks and Eris (lakes) in many places have disappeared, but canals alone remain,” he says.
When Express visited many localities in Zamin Pallavaram, canals were largely re-routed but large tracts of waterbodies were turned into garbage dump yard and apartment complexes.
Is Chennai prepared?
It has been almost four years since the 2015 floods, but not much has changed on the ground given the state of rivers, canals and stormwater drains in the city. “There seems to be no change from 2015 and if rains cause floods again, Chennai will get inundated,” says Janakarajan.
Sivagnanam, who also has expertise in weather prediction for over four decades, says the northwest monsoon would be very strong this year. “There is a lot of chance for flooding,” he says.