Chennai’s rapid urbanization has encroached on the city’s natural landscape, reducing water retention capacity, which makes the city vulnerable to widespread flooding. Frequent floods in recent years have destroyed property and livelihoods. The ADB-funded project interventions are helping the city reduce the vulnerability of Chennai-Kosasthalaiyar basin residents to frequent floods. The ADB project is helping build flood protection infrastructure, including stormwater drains, improving water channels to enhance water-carrying capacity, and installing pumping stations. It is also constructing catchpits in roadside drains to recharge the groundwater aquifer and rehabilitate four disaster relief camps. Besides, the project is helping strengthen the capacity of the Greater Chennai Corporation and the communities for better preparedness planning to transform Chennai into a more livable city. The innovative designs and interventions for climate-resilient flood management promoted by the project, with integrated urban planning and enhanced municipal resource mobilization, can be widely replicated for other Indian cities vulnerable to climate and disaster risks.

Transcript

Chennai is the fourth largest metropolitan area and one of India’s fastest-growing major cities. Unplanned settlements and pollution often lead to clogging of the city’s water bodies and drainage channels, causing frequent flooding.

The risk further rises with the city’s low and flat location. Over the past decade, Chennai has endured more frequent and intense flood extremes.

TOS: Chennai’s average elevation is 6.7 meters above sea level.

TOS: Chennai’s worst flood in 2015 claimed over 400 lives.

The risk of flooding in Chennai is expected to worsen with climate change.

TOS: Heavier rainfall and storm surges from cyclones to cause frequent floods

The city urgently needed to build its climate and disaster resilience to protect lives and livelihoods. In September 2021, ADB approved a $251 million loan to support the Greater Chennai Corporation to enhance integrated urban flood management in the Chennai-Kosasthalaiyar River Basin. 

TOS: ADB’s $251 million loan supports the Greater Chennai Corporation’s urban flood management project.

Several flood protection measures are being undertaken. These include construction of storm water drains and upgradation of water channels to enhance their water-carrying capacity. Storm water pumping stations are being installed or upgraded.

The impact of some of these measures is already being seen. Several flood-prone areas in the city reported no waterlogging during the rainy season in 2022.

TOS: Communities happy with no waterlogging reported in the rainy season.

Manjula, Resident along watercourses 

Five years ago, we used to struggle a lot as the rainwater used to come right up to our front door. Sometimes, water used to enter inside our house. As a result, we were forced to seek shelter at someone else’s home. During rains, flood water used to rise to the level of cupboard shelves.

Shanthi, resident Slum Area Chennai

Last year we faced a lot of problems (due to flooding). We had to stay on the terrace, and eat food provided by the corporation. We are not facing any trouble this year because of the canal (stormwater drain).

Since Chennai also experience drought, the project is helping construct more than 20,000 catchpits in roadside drains to recharge the groundwater aquifers.

Further, recognizing the complex causes of urban flooding, the city is implementing measures to raise awareness among communities. These are meant to improve preparedness planning and promote behavioral change.

TOS: Flood preparedness built with institutional strengthening and awareness raising activities

Akira Matsunaga
Principal Urban Development Specialist
Asian Development Bank

Our flood risk management has robust and holistic approaches with adaptive interventions to future uncertainty. We optimally combine structural measures to control water flow and non-structural measures to improve preparedness planning and promote people’s behavioral change.

An additional grant from Global Environment Facility is helping rejuvenation of Kadapakkam Lake to enhance its flood retention capacity.  

Gagandeep Singh Bedi
Commissioner
Greater Chennai Corporation

The integrated flood risk management project, that is the Kosasthalaiyar project, being undertaken in Chennai is a very important project for the Greater Chennai Corporation. We have already, so far, completed about 40% of the project. So, the project actually had a very promising outcome so far and we feel that once the project is completed, it will definitely save large parts of northern Chennai from huge inundation which was a routine news every year during the northeast monsoon season.

Flooding also carries the risk of spread of pandemic and communicable diseases. To reduce this risk, a Government of Japan (Japan Fund for Prosperous and Resilient Asia and the Pacific) grant will strengthen water, sanitation, and hygiene services in public schools and urban primary health centers. 

TOS: Grant to build resilience to future pandemics in flood-prone areas

Gagandeep Singh Bedi
Commissioner
Greater Chennai Corporation

We are also undertaking a lot of innovations in the project such as going for rainwater harvesting structures along the storm water drains, putting up of sponge parks across various places where water can be stored and water table can be recharged etc. 

This holistic approach to build city’s resilience to floods and future pandemics will transform Chennai into a more livable and safer city

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