New Delhi, Apr 22 (PTI) The uptake of permeable pavements could enhance stormwater drainage capacity, reducing surface runoff and mitigate flood risks, according to a new report by the Centre for Study of Science, Technology and Policy (CSTEP).

The report titled “Urban Greenprints: A Nature-based Solutions Feasibility Framework for Urban Coastal Regions” by the Bengaluru-based think-tank has called for a paradigm shift in how India’s coastal cities approach urban planning and climate resilience.

Focusing on Chennai and Mangaluru in Karnataka, the report makes a compelling case for integrating Nature-based Solutions (NbS) in urban planning to address the escalating challenges of flooding, environmental degradation, and climate-induced vulnerabilities.

“Both cities have witnessed a sharp decline in green cover and increased encroachments on natural water bodies. These changes, compounded by extreme weather events, have exposed the limitations of conventional grey infrastructure such as stormwater drains and concrete embankments.

“There is urgent need to embrace NbS such as wetland restoration, rooftop greening and permeable pavements — as part of a more sustainable and resilient urban strategy,” the report said.

Drawing on in-depth assessments of 23 wards in Chennai and four wards in Mangaluru, the study evaluated the feasibility and impact of NbS interventions.

Among the main findings is the significant potential for rooftop greening, which could expand NbS-covered areas by 76 per cent in Chennai and 80 per cent in Mangaluru within the selected study regions.

“In both cities, the uptake of permeable pavements could enhance stormwater drainage capacity by 5 per cent, reducing surface runoff and mitigating flood risks. Optimising the existing waterbodies for flood mitigation, groundwater recharge, and biodiversity emerged as a particularly critical strategy,” it said.

The report also featured several NbS case studies in the study regions that highlighted the ecological and functional importance of natural systems.

“However, encroachment and degradation of these ecosystems have diminished their climate adaptation potential, worsening urban vulnerability. Revitalising such natural assets is essential not only for climate resilience but also for promoting co-benefits, such as eco-tourism, sustainable fishing and other livelihood opportunities,” it said.

Lakshmi Menon, senior analyst in the adaptation and risk analysis group at CSTEP, noted that 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,” Menon said.

The report recommended that policymakers in the study regions embed NbS within their core climate resilience strategies.

“This includes updating urban planning regulations to accommodate nature-based infrastructure, directing public funds toward NbS projects, and prioritising interventions in areas that are most vulnerable to climate stress. “It also urges local governments to take the lead in piloting scalable NbS initiatives, leveraging data and technology for better decision-making, and fostering collaborations across sectors and stakeholders,” the report said. PTI GJS ARI