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Vol. XXXIV No. 9, August 16-31, 2024
Chennai Turns into Lake District
-- A Resident of Alwarpet
The city of Chennai is turning into a new Lake District! This is happening every time there is a downpour for a couple of hours. Buildings and houses are getting flooded, forcing people out of their homes to take shelter elsewhere for days. With power connections shut off as a precaution, sewers mingling with rainwater and contaminating the water supply, living inflooded areas becomes a nightmare. Loss of property, home and livelihood becomes the common woe of all strata of society. Can we blame it all on excessive rainfall? More conveniently, on climate change? Can we turn a blind eye to the idea that it could be a man-made calamity?
Floods of Chennai. Picture courtesy: The Hindu.
When the problem of flooding was recognized, the government tried to impose regulations to require rainwater harvesting, making it mandatory for every building to build underwater sumps and fix pipes and conduits to take in all the rainwater falling within the compound and on the roof within the plot, in order to recharge its groundwater. This is when it was recognized that the city had become one vast expanse of concrete with very little open soil to take the water.
It was soon found that the rainwater saving was effective only partially as the sumps were full within a couple of hours of rain and the recharge wells only a few more. It took several hours or days for the water levels to recede.
The stormwater drains had been constructed with poor planning and coordination – for example, many roads in Chennai still have stormwater drains only on one side, unlike in Bangalore where they are on both sides of the road. Instead of taking the drains to the nearest waterway, the drains in Chennai simply meander from one flooded area to another, with longwinded routes making it harder to reach canals. Also, as the drains were constructed by different contractors in the same locality, the quality of construction has varied widely and waterflow has been haphazardly directed.
The latest threat, we are given to understand, is from metro stations during the rains, as they start pumping out very large volumes of water onto the roads. This is contrary to the existing system in which water is required to be pumped out into pipes or dedicated channels to the nearest river or canal.
Above all, the single largest contributing factor to flooding is the continual raising of road levels all over the city since the year 2000. In the last two decades, road laying has become fully mechanized with machines, which lay a long stretch of road in a few hours overnight. No more transporting lorry loads of crushed large stone jelly, spreading them and binding them with melted tar. All this was manually done earlier and required a sizeable workforce. The surface was then smoothened and hardened by slowly running road-rollers back and forth. Now the crushed stones and binding material are combined in the modern machines which roll out the mix in a matter of minutes.
There is a lot of talk from the authorities at all levels about cold milling of the roads. This means that the top layer of the road is removed and recycled into material for new road. Theoretically, this is to retain the road at the same level as earlier and to harden and smoothen the new layer. In practice, the half-hearted and haphazard raking of the top two inches actually raises the road level by six to eight inches overall when the fresh material is applied on top.
As a result of years of such shoddy road laying, roads have risen by two to three feet in all areas, lowering houses and plots on either side, effectively ensuring that all the rainwater rushes into them, leaving the roads dry. In our Alwarpet area, the roads have been raised by three feet in the last twenty years. To make things worse, rainwater flowing out of the roofs and grounds of buildings on either side flow onto the roads, augmenting the volume of rainwater looking for lower-lying areas and eventually creating new lakes of standing water two to three feet deep inside houses and buildings for days.
Roads are the widest and longest channels to help the rainwater flow out to the nearest canal or river taking the water to the sea. Where rainwater stagnates, the stormwater drains are to take over this role. This simple arrangement has been either forgotten or negated. Raising the road levels means that every drop of rainwater has to flow only through the stormwater drains, which is impossibly higher than the volume for which the drains have been constructed.
It may sound impractical and unfeasible to propose lowering the level of the roads as the best solution to prevent flooding. However, if the levels are reduced by six to eight inches repeatedly in a phased manner by better road laying practices that are true to their design, Chennai could regain the status of a well-built city. It should be remembered that even 45 cms of rain in 24 hours, as the city experienced on the 26th of November 1976, did not flood the habitations of people.
A case study is the flooding in the Alwarpet area in December 2023. With heavy rains, the water level on the roads was rising slowly around 3rd December. Suddenly at 6 am on 4th December, a flood of water converged into the area and within half an hour, water rose by four feet on the road and entered all houses and buildings and remained for the next four days. People had to leave their homes or remain in the upper floors until water receded or was pumped out. Even those lucky enough to move to higher levels had to contend with no power, provisions or sewerage for days.
Bad planning and the wrong flood control measures caused this disaster.
The problem had started long ago when stormwater drains in Alwarpet area were re-designed and constructed to converge at a single point at the junction of Sriman Srinivasa Road and Kasturi Ranga Road – this location could not take the volume of water from rains even prior to 2015. In 2023, new storm water drains were constructed to bring even more water from Cathedral Road and the Poes Garden area to reach this same point, despite protests from residents.
On 4th December, rainwater from Anna Salai in the Teynampet area was also directed to this same spot. This poorly designed and executed flood prevention plan actually caused flooding through Varadarajapuram and Sriman Srinivasa Road. The massive volume of water gathered from all the nearby locations had nowhere to go – the drain that crossed TTK Road and wound through Luz Church Road to eventually reach Buckingham canal had been mostly blocked by the Metro rail project, with no alternative route provided for flooding rainwater to reach a waterway.
This scenario has played out repeatedly in several parts of the city, rendering Chennai a lake district! A complete overhaul of the rainwater management and flood prevention system, including simple but powerful changes in design and construction, is the urgent need of the hour. Survey and planning of the drains system by experts is desperately needed. Changes in construction of stormwater drains and lowering of roads must be taken up simultaneously. Instead of engaging a medley of private contractors for each road in an area, each area should be given to reputed private construction firms to standardize construction and be held responsible for maintenance and lapses. If the political will to adopt this major reformation in urban planning can be found, widespread citizen support is sure to follow, for this concerns their homes and livelihood. We need to act NOW to save this beautiful city from the terror of floods caused by Act of Man.
