Nature-based Solutions Crucial For Climate-resilient Coastal Cities, Finds CSTEP Report
New framework highlights cost-effective, scalable strategies for integrating natural infrastructure into urban planning in Chennai and Mangaluru
As climate change continues to intensify threats to India’s coastal cities, the Center for Study of Science, Technology and Policy (CSTEP), a Bengaluru-based think tank, has released a report advocating for Nature-based Solutions (NbS) as a core strategy in urban resilience. Titled Urban Greenprints: A Nature-based Solutions Feasibility Framework for Urban Coastal Regions, the report focuses on Chennai and Mangaluru—two cities grappling with climate-induced flooding, declining green cover, and encroachment on water bodies.
The report urges a shift from traditional grey infrastructure—like stormwater drains and concrete embankments—towards nature-based alternatives such as wetland restoration, rooftop greening, and permeable pavements. These NbS interventions, the report states, are not only environmentally sustainable but also economically prudent, delivering multiple social and ecological benefits alongside flood mitigation and climate adaptation.
Key findings from the study underscore that NbS can significantly scale urban green coverage and improve resilience in vulnerable wards. In 23 wards of Chennai and 4 wards in Mangaluru, rooftop greening alone has the potential to increase NbS-covered areas by 76 per cent and 80 per cent, respectively. Permeable pavements could boost stormwater drainage capacity by 5 per cent, helping reduce surface runoff and flooding.
Drawing from detailed assessments and case studies, the report makes a strong case for integrating NbS into policy, planning, and budgeting processes—rather than treating them as standalone or experimental solutions. Community involvement and data-backed monitoring are identified as critical to ensuring local relevance and long-term effectiveness.
Lakshmi Menon, Senior Analyst at CSTEP, stated, “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.”
CSTEP’s cost–benefit analysis reinforces this point. In the Chennai study area, an investment of Rs 2,203 crore in selected NbS projects could result in annual savings of Rs 505.31 crore from avoided flood damages, with a payback period of just over four years. Similarly, in Mangaluru, a smaller investment of Rs 172.97 crore could generate Rs 11.62 crore in annual savings, becoming cost-positive by 2027.
To operationalise these recommendations, the report proposes a phased roadmap: beginning with community engagement and pilot projects, then scaling up successful interventions, and finally embedding NbS into the regulatory and policy fabric of urban governance. It also highlights the need for local governments to lead the way in piloting scalable projects, leveraging technology, and forging cross-sector partnerships.
