Indian coastal cities can save Rs 505 crore annually by avoiding flood damages

Nature based solutions (NbS) for urban planning such as wetland restoration, rooftop greening, and permeable pavements will not only offer critical environmental benefits for India’s coastal cities, but also deliver strong economic returns, a study found on Wednesday.

In Chennai, an investment of ₹2,203 crore in select NbS could save over ₹505 crore annually in avoided flood damages, paying for itself in just over four years. In Mangaluru, a more modest ₹172.97 crore investment could become cost-positive by 2027, with annual savings of ₹11.62 crore.

The Center for Study of Science, Technology and Policy (CSTEP), a Bengaluru-based think tank in its report , Urban Greenprints: A Nature-based Solutions Feasibility Framework for Urban Coastal Regions, called for a paradigm shift in how India’s coastal cities approach urban planning and climate resilience.

Focusing on Chennai in Tamil Nadu and Mangaluru in Karnataka, the report emphasized that using NbS can address the escalating challenges of flooding, environmental degradation, and climate-induced vulnerabilities.

The study, conducted in 23 wards of Chennai and 4 wards of Mangaluru, found significant untapped potential for NbS implementation. Rooftop greening alone could expand NbS-covered areas by 76% in Chennai and 80% in Mangaluru. Permeable pavements could improve stormwater drainage by 5%, easing flood risks in vulnerable areas, the report read.

“Even modest ward-level investments in green infrastructure can yield substantial long-term savings and ecological benefits,” said Lakshmi Menon, Senior Analyst, Adaptation and Risk Analysis group, CSTEP. She added that as climate risks intensify, integrating NbS into urban planning is not just desirable—it is essential for building resilient, adaptive, and sustainable cities.

To translate these insights into action, the report proposes a phased roadmap of urban NbS uptake. The first step involves engaging local communities, raising awareness, and initiating pilot projects to demonstrate the effectiveness against localised climate risks. Building on their success, the next step is to scale up interventions and align urban development policies with NbS objectives.

“With rising sea levels, erratic rainfall, and increasing temperatures posing serious risks to urban infrastructure and public well-being, the NbS feasibility framework offers a replicable model for all cities seeking sustainable development pathways,” the report said.

In both cities, the uptake of permeable pavements could enhance stormwater drainage capacity by 5%, reducing surface runoff and mitigating flood risks. Optimising existing water bodies for flood mitigation, groundwater recharge, and biodiversity was suggested as a critical strategy.