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Chennai Floods: What is the way forward for a developing Chennai vulnerable to flooding?

Dec 13, 2023 05:48 PM IST

Long-term solutions lie in engineering water flow and re-urbanisation of a dense population that is living in Chennai’s low-lying areas, say experts.

Last week’s Cyclone Michaung, which struck on December 4, killing at least 20 people and marooning tens of thousands of residents in Chennai, has raised questions on what solutions can be taken to lessen the impact of such flash floods.

Emergency services personnel evacuate stranded residents from a flooded colony after heavy rainfall owing to Cyclone Michaung, at Mylapore in Chennai, on Wednesday. (PTI) PREMIUM
Emergency services personnel evacuate stranded residents from a flooded colony after heavy rainfall owing to Cyclone Michaung, at Mylapore in Chennai, on Wednesday. (PTI)

The northeast monsoon (October to December) is Tamil Nadu's chief rainfall season, contributing more than 40% of its annual rainfall. Still, it is associated with tropical cyclones, flash floods and widespread distress. In Chennai, the floods caused by Cyclone Michaung brought back haunting memories of the December 2015 floods, caused by a combination of extreme weather and mismanagement of the city's reservoirs, which led to the deaths of more than 200 people. Experts say that cyclone-related flooding has submerged much of the city in a similar manner way back in 1943, 1978 and 2002.

By now, from past experiences of flooding in Chennai, it has become common wisdom that the city floods due to a combination of reasons -- its coastal geography, flat terrain, massive urbanisation on water bodies and climate change causing extreme weather patterns. What are the options that Chennai has under such vulnerabilities?

Dense urbanisation leading to worsening floods

While the present government has increased the network of stormwater drains, Chennai's suburbs, added to the city from the north, south and west, remain underserviced, which is where stormwater continues to stagnate for at least four days. Officials have to rescue residents in these areas in boats. The cyclone has also shown that the role of drains is limited and shone a light on how long-term solutions would look in terms of drafting a city plan for development while protecting the paths of water flow.

Chennai now has dense urbanisation and high rises on its flood plains. Ironically, the government in the last decade has also relocated flood-affected families from the city’s core areas to the peripheries which are on the flood plains.

“Floods in certain low-lying areas cannot be avoided,” says geospatial analyst Raj Bhagat. “Permission should not have been given to build here but now that the mistake has been made it has to be corrected,” says Bhagat. He suggests that the government survey the lock-in period of infrastructure for the people living in low-lying areas and devise a rehabilitation plan to move them – from low-income families in tenements to those living in gated communities and high rises. “The government has to strategise when and how to carry out an urban redevelopment and provide specific plans for various sections of people,” Bhagat says. “It will be slow and costly but people can’t live like this forever. Eventually, they will have to move.”

Lack of public accountability in city planning is exacerbating floods

There is not much public accountability in city planning. The third master plan for the Chennai metropolitan area (CMA) which includes suburbs from Chennai’s adjoining districts of Thiruvallur, Kanchipuram, Chengalpattu and Ranipet is under revision, a government official said. “Issues of flooding, and real estate development near water bodies will be considered before finalising the third master plan,” the official said. In October 2022, the CMA expanded to 5,904 sq km. The city’s nodal planning agency, the Chennai Metropolitan Development Authority (CMDA), headed by the Tamil Nadu housing minister, issues approvals for any development within the CMA. Experts have long said that without a plan for draining flood water, building approvals must not be given by the agency.

Mark Selvaraj, an expert in urban infrastructure and stormwater drains, talked about the creation of a singular authority to approve a building’s stormwater draining plan, similar to how the CMDA is in charge of approving a building plan. “The rains we received now and back in 2015 occurred 50 years ago as well, but then the city was in a pre-development phase so the rainwater receded to canals and rivers before it reached the sea,” says Selvaraj.

"Under current circumstances, the network of stormwater drains has to be designed in a way that mimics the hydrology of its natural flow. Decades ago, stormwater reached the sea in an hour, and now the drains take the urban runoff to sea within 10 to 15 minutes," says Selvaraj. "When the rivers and sea have reached their capacity there is no way for the stormwater to be let off, resulting in inundation."

“Officials are going to the disposal points (of stormwater) and scratching their heads trying to figure out how to dispose of so much water,” says Selvaraj. This should not be the case, he says, adding that city planners should find land space where flood water can be retained before being disposed of to the final point at sea, which here is the Bay of Bengal. “Now nature is finding its own retention space, leading to rainwater accumulating in the roads and slowly receding,” he says. “So, we have to work backwards, starting from the last disposable point, and leading towards people’s doorsteps. But, currently, the opposite is being done.”

Time-sensitive policy solutions for the urban crisis

The current government formed a committee under retired IAS officer V Thiruppugazh to offer flood mitigation solutions who submitted a report in May but it has not been made public resulting in no engagement with stakeholders.

Places such as Pallikaranai (a marshland) and low-lying areas of Velachery and Madipakkam require special attention, says Selvaraj. “Only constricting stormwater drains here will not help,” he added. “The only way out is restoring the losses we have created in Velachery Lake and Pallikaranai marshland, which are natural retainers of rainwater.”

Raj Bhagat calls for granular information and extensive mapping of low-lying and flood-prone areas in the CMA. Planning only for Chennai in silos through the Greater Chennai Corporation (GCC) has not helped. “Urban local bodies besides the GCC have to be strengthened with finances and manpower such as urban planners, and hydrologists,” he says. “We may have hundreds of wonderful ideas but we need governance, finance and manpower to execute them. Only then, the technicalities of mitigating a flood will fall into place.”

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  • ABOUT THE AUTHOR
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    Divya Chandrababu is an award-winning political and human rights journalist based in Chennai, India. Divya is presently Assistant Editor of the Hindustan Times where she covers Tamil Nadu & Puducherry. She started her career as a broadcast journalist at NDTV-Hindu where she anchored and wrote prime time news bulletins. Later, she covered politics, development, mental health, child and disability rights for The Times of India. Divya has been a journalism fellow for several programs including the Asia Journalism Fellowship at Singapore and the KAS Media Asia- The Caravan for narrative journalism. Divya has a master's in politics and international studies from the University of Warwick, UK. As an independent journalist Divya has written for Indian and foreign publications on domestic and international affairs.

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