Chennai Deluge: Even Rajini Couldn't Escape Waterlogging, Here's Why

Chennai, the capital of Tamil Nadu, which is home to an estimated over 12 million people, including the Tamil superstar and his family, was flooded after near non-stop rain from December 3 to December 5. The last two days saw some 400 mm rainfall in Chennai district, which is almost half a metre. The city and its residents were left helpless and raging. Poes Garden, the plush neighbourhood where Rajinikanth has his home, was flooded even on December 9, imagine the plight of the common citizens.

The rain this year was much more than the 2015 downpour. The city's suburbs, built over catchment areas, floodplains and lakebed areas, were worst hit with waist-deep water.

Haphazard development and commissioning of ambitious projects without due diligence and adherence to planning protocols have left Chennai unable to withstand ordinary monsoons. Add to this, the heavy rainfall brought along by the slow-moving Cyclone Michaung.

Chennai has suffered the consequences of heavy rain and cyclones almost once every decade, sometimes twice. So are residents justified in blaming politicians, or planners, or climate change or is it a combination of these factors?

In 2015, J. Jayalalitha, the then chief minister, had tried to normalise a man-made calamity. "Losses are unavoidable when there is a lot of rain. Only prompt rescue and assistance are indicators of good governance," she had said, glossing over the near zero attention paid to urban development by successive governments in the state.

What Happened?

The India Meteorological Department (IMD)'s latest update revealed that Cyclone Michaung brought a staggering 29% more rainfall to Chennai. The weakened monsoon conditions observed during June and August provided an environment conducive for precipitation to accumulate substantially.

September saw a different meteorological dynamic, leading to thunderstorms in parts of leeward peninsular India amid active monsoon conditions. Traditionally, during peak monsoon, the leeward areas of coastal Tamil Nadu remain relatively dry due to the wind shear (how the wind changes speed or direction with altitude). However, this time, the active monsoon conditions were expected to act as conduits for remnant moisture from the West.

Thus, moisture from the West traversed to the East Coast, interacting with ascending air particles heated during the day over interior Tamil Nadu. This interplay created conditions for thunderstorms.

The Northeast Monsoon, the retreating monsoon, is the primary rainfall season for most of Tamil Nadu. According to the Climatological Normal Data from IMD spanning 1991 to 2000, the seasonal mean rainfall during Southwest Monsoon (June to September) is documented at 474 and 440 mm for Chennai AP and Chennai Nungambakkam, respectively. This amounts to one-third of the annual rainfall received by these observatories, with the Northeast Monsoon contributing nearly 60% of the annual precipitation.

Chennairains.com, a platform for amateur weather enthusiasts, noted on September 8, 2023 that with three weeks still to go in the month, the cumulative Southwest Monsoon rainfall for Chennai AP and Chennai Nungambakkam stood at 774 and 597 mm. The normal rainfall at this point at Chennai AP has been approximately 390 mm. This illustrates that the Southwest Monsoon tally this year is nearly twice the usual recorded during this period and points to anomalous climatic conditions.

The Consequences

In July 2023, LocalCircles, an open platform survey site, conducted an online survey on waterlogging and its resultant issues. Of about 15,000 respondents, more than half said the water-logging situation was bad.

Apart from waterlogging making streets inaccessible, respondents said vehicles are damaged due to water getting into their engines, causing expensive repairs. Slums and unauthorised settlements become easy prey for long-term diarrhoeal infections that pose health risks. With livelihoods of hawkers, sanitation workers, and others so jeopardised, their incomes are impacted.

The survey shed light on the negative impact on citizens' minds. Submerged open manholes posed a challenge for commuters and the flood water poured into basements and invaded ground-floor residences.

Such waterlogging underscores the need for comprehensive measures to address vulnerabilities caused by it. Mitigation here should not only be of infrastructure improvements but also include strategies to lessen the broader socio-economic ramifications on people.

The Man-Made Factors

Reporting on the 2015 Chennai floods, Ravish Kumar put it pithily, “If we construct (on) water catchments and basins, water will have nowhere to go so it will take main roads to make its way out”.

In pursuit of progress, Chennai witnessed the emergence of a lot many infrastructure projects that compromised the city's resilience to the monsoon. The construction of an airport on the Adyar river floodplains, a bus terminal in flood-prone Koyambedu, and the Mass Rapid Transit System stations along the Buckingham Canal and Pallikaranai marshland are examples of such development.

Expressways and bypasses have come up with disregard for the natural flow of water, and corridors dedicated to IT and Knowledge, featuring engineering colleges constructed on water bodies, have added to the urban landscape. Zones designated for automobile and telecom industries, as well as gated colonies, have swamped drainage courses and catchment zones.

The transformation of the Pallikaranai marshland serves as a poignant example; once spanning 50 square kilometres in the southern suburbs, it is now reduced to 4.3 square kilometres – less than a tenth of its size.

Even institutions like the National Institute of Ocean Technology, entrusted with preparing environmental impact assessments, including those related to water body construction, have encroached onto the marshland.

The Chennai Bypass, which links NH45 and NH4, has emerged as a bottleneck for eastward drainage, resulting in flooding in Anna Nagar, Porur, Vanagaram, Maduravoyal, Mogappair, and Ambattur. The lakes of Maduravoyal, Ambattur, Kodungaiyur, and Adambakkam, as well as drainage routes from Korattur and Ambattur ponds, have become ponds or have disappeared. Crucial flood retention facilities, including tanks at Virugambakkam, Padi, and Villivakkam, have been abandoned.

Mitigation Measures

1.Better land use planning: What can one ask of a city if its airport is the first to go under? One can sense that land use plans have been ignored. Clearly, the city did not take into account pre-existing lakes, catchment areas, or topography in general. If more land is brought into urban usage without due thought, the issue would only worsen, not only for Chennai but also for the rest of India's cities.

2.Control over new projects and projects already in the works: There are numerous mega projects proposed or under construction that will be announced or completed in the near future, including the Chennai peripheral ring road, Chennai Metro phase 2, Surat-Chennai express highway. Some of these projects will need to be re-evaluated and aligned with the terrain and catchment areas.

3.Declogging drives and issuing waste disposal guidelines: Among reasons water can't exit through the drains and accumulate on the road is that parts of open drains are used as dustbins, and normal waste management methods lead to obstructions. To prevent this from recurring, a systematic effort to unclog drains and waste management standards must be implemented.

4.Reassessing the city's storm water drainage system: It's not ideal for a city to be at sea after two days of heavy rain. Along with urban projects and clogged drains, the total length of storm water drains must be re-evaluated. This will aid in redesign of drainage systems in and around prospective mega projects.

5.Redevelopment of unauthorized land, low lying places: Low-lying areas, particularly unauthorized colonies, are the first to suffer since they have no planning layouts, making it difficult to regulate stormwater at street and settlement levels. This hits the poor hardest, impacting both their livelihood and health.

6.Efficient and prompt warning and relief systems: From Chief Minister Stalin donating his salary to the state relief fund to the centre releasing a Rs 450 crore package, there is no shortage of money or intent to help the people of Chennai. However, the state must be more proactive in giving food and financial support to its inhabitants. Some effort to ensure the safety of children and the elderly in risk districts, as well as extra precautions for sensitive neighbourhoods, will reduce loss of life and the suffering caused by flooding.

While we need relief and warning systems, there is a natural connection between preventative and crisis-response measures. Better spatial planning and project re-evaluation are first steps for the long-term mitigation of this issue. That is how structural resilience is built.

If we envision taller skylines and wider streets, we must dig deep, both metaphorically and physically, to ensure the drains can accommodate both city life, regular rainfall and floods. We're certain Rajini won't mind!