As flash floods wreak havoc across metros during rainfall, a recent study by theCenter for Study of Science, Technology and Policy (CSTEP) details the steps that Chennai can take to address the challenges of climate extremes.
The research indicated that in selected wards in Chennai, implementing green spaces, urban farms, permeable pavements, and restored wetlands can significantly improve resilience to urban flooding, with co-benefits such as mitigation of heat stress and pollution reduction, while making the city more liveable.
For instance, the report notes that, in the studied wards in North Chennai, even the modest use of green rooftops, such as turning bare concrete surfaces into low-cost, low-maintenance gardens, could boost local green cover by over 70 per cent, the report said. This will result in a major cooling effect in areas that are often the hottest, most crowded, and least green parts of the city.
Besides bringing temperatures down, rooftop gardens can help with rainwater absorption and even supply produce for households, the report adds.
However, the proposed nature-based solutions require substantial investment.
The report estimates that around ₹2,203 crore would be needed to put key nature-based solutions into action across selected wards in the city.
But it also finds that the economic benefits, like reduced damage from floods, could amount to over INR 500 crore in savings each year. Essentially, Chennai could recover the costs in over 4 years, the report notes. “Without intervention, Chennai risks Rs 10,000 crore in climate-related damages over the next 2 decades,” it adds.
Lakshmi Menon, Senior Analyst in the Adaptation and Risk Analysis group at CSTEP, highlights, ‘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.’
Chennai’s wetlands are another key part of the solution. Neighbourhood lakes and river catchments can serve as natural sponges, absorbing excess water during storms and filtering pollutants. Preserving and expanding these ecosystems can help protect neighbourhoods from flooding while supporting birds, fish, and other wildlife that are part of Chennai’s natural heritage.
Published on May 20, 2025