₹2,203 crore green push can ease Chennai's climate challenges: CSTEP

Business Standard

19-05-2025

Chennai, which frequently experiences heavy rains and floods, could save around ₹500 crore in reduced flood damages and co-benefits each year by investing ₹2,203 crore in key nature-based solutions across selected city wards, according to a study by the Center for Study of Science, Technology and Policy (CSTEP).
Nature-based solutions must be embedded in planning, budgeting and policy processes rather than treated as standalone initiatives, said the report titled Urban Greenprints: Leveraging Nature-based Solutions (NbS) to Address Urban Climate Risks. While Chennai is making steady progress through its climate action plans and green initiatives, the study highlights the need for further steps to tackle challenges such as heatwaves and flash floods.
The research indicated that in selected wards, implementing green spaces, urban farms, permeable pavements and restored wetlands could significantly improve resilience to urban flooding. These measures would also help mitigate heat stress, reduce pollution and enhance overall liveability.
Many proposed ideas are simple and cost-effective. For instance, in North Chennai wards, converting bare concrete rooftops into low-cost, low-maintenance gardens could increase local green cover by over 70 per cent. This would cool some of the city's hottest and most densely populated areas. In addition to reducing temperatures, rooftop gardens can absorb rainwater and provide household produce.
Streets can also contribute to climate resilience. The report notes that switching to permeable surfaces in flood-prone areas would allow rainwater to seep into the ground, helping to recharge groundwater and reduce waterlogging.
Chennai's wetlands form another essential part of the solution. Neighbourhood lakes and river catchments can act as natural sponges, absorbing stormwater and filtering pollutants. Preserving and expanding these ecosystems would not only protect against flooding but also support birds, fish and other native wildlife.
The report cites existing on-ground initiatives that have demonstrated success. For example, the Chennai Urban Farming Initiative has introduced rooftop and mobile gardens in schools, homes and homeless shelters. These help cool buildings, grow food and create learning opportunities and jobs—especially for women and young people. In a city with limited land, using rooftops effectively is a smart and inclusive strategy.
'These changes require investment. We estimate that around ₹2,203 crore would be needed to put key nature-based solutions into action across selected wards in the city,' the report said. It also noted that the potential economic benefits, such as reduced flood damage, could yield annual savings of over ₹500 crore—meaning the investment could be recovered in just over four years.
What makes the approach especially appealing is its flexibility. Projects can start small—such as a community wetland park or a few green rooftops—and scale up over time. The aim is not to overhaul the entire city at once, but to create context-specific solutions developed in collaboration with communities.
Lakshmi Menon, Senior Analyst in the Adaptation and Risk Analysis group at CSTEP, said: 'In cities like Chennai and Mangaluru, even modest ward-level investments in green infrastructure can yield substantial long-term savings and ecological benefits. As climate risks intensify, integrating nature-based solutions into urban planning is not just desirable—it is essential for building resilient, adaptive and sustainable cities.'