Nature-Based Solutions Key to Building Climate Resilience in India’s Coastal Cities: Study

As climate change intensifies globally, coastal cities face a particularly severe set of challenges — from rising sea levels and flooding to the degradation of natural ecosystems. A new report titled “Urban Greenprints: A Nature-based Solutions Feasibility Framework for Urban Coastal Regions”, published by the Bengaluru-based think tank Centre for Study of Science, Technology and Policy (CSTEP), underscores the importance of integrating nature-based solutions (NbS) into urban planning for India’s coastal cities. Focusing specifically on Chennai and Mangaluru, the report offers valuable insights and strategies that could potentially redefine urban development across the country.

The Need for a Paradigm Shift in Urban Planning

India’s coastal cities are rapidly urbanising, but the expansion has come at a cost. Natural ecosystems, such as wetlands, green spaces, and water bodies, have been systematically replaced by concrete structures and grey infrastructure. This has not only increased vulnerability to climate events but also reduced the cities’ innate capacity to absorb environmental shocks.

Chennai and Mangaluru, for instance, have both witnessed a steep decline in green cover and increasing encroachments on natural drainage channels and wetlands. Conventional grey infrastructure, like stormwater drains and embankments, has proven insufficient in managing the growing threats of urban flooding, especially during intense rainfall events. This has made the need for sustainable and adaptive urban solutions more urgent than ever.

What are Nature-Based Solutions?

Nature-based Solutions (NbS) use strategies that leverage natural systems or mimic ecological processes to address societal challenges. In urban contexts, this includes measures like wetland restoration, rooftop gardens, permeable pavements, urban forests, and the rejuvenation of lakes and other water bodies.

Unlike conventional infrastructure, NbS provides co-benefits that go beyond its primary function. For example, a restored wetland can not only manage floodwater but also improve water quality, recharge groundwater, support biodiversity, and offer recreational spaces for residents.

Key Findings from the Report

The CSTEP report conducted an in-depth assessment of 23 wards in Chennai and four wards in Mangaluru to evaluate the feasibility and impact of various NbS interventions. Several promising insights emerged:

1. Rooftop Greening Potential
   One of the most significant findings is the high potential for rooftop greening. In the study regions, Chennai could see a 76% increase and Mangaluru an 80% increase in NbS-covered areas through this single intervention. Rooftop gardens can lower urban heat, reduce runoff, and promote biodiversity in densely built environments.
   
2. Permeable Pavements for Flood Control
   The study found that even partial adoption of permeable pavements could enhance stormwater drainage capacity by 5%, reducing surface runoff and mitigating flood risks. This is particularly crucial in cities like Chennai, where urban flooding is a recurrent issue.
   
3. Reviving and Optimising Water Bodies
   Another critical strategy highlighted was the optimisation of existing water bodies. By restoring ponds, lakes, and canals, cities can improve flood mitigation, enhance groundwater recharge, and support aquatic biodiversity. These restored water bodies can also serve as community spaces that contribute to well-being and resilience.
   
4. Cost-Benefit Analysis Favors NbS
   The financial analysis in the report makes a strong case for investment in green infrastructure. In Chennai, an estimated investment of INR 2,203 crore in select NbS could save INR 505.31 crore annually in avoided flood damages, achieving a payback period of just over four years.
   Mangaluru, with a smaller required investment of INR 172.97 crore, could break even within 15 years, with cost-positive returns starting as early as 2027. These figures are based on conservative estimates, suggesting actual savings may be even greater.
   

Long-Term Ecological and Economic Gains

Beyond immediate cost savings and disaster mitigation, NbS offers long-term ecological and social benefits. They enhance urban biodiversity, improve air and water quality, reduce urban heat island effects, and create green jobs. In densely populated cities, they also offer residents much-needed green spaces that promote mental and physical health.

Lakshmi Menon, Senior Analyst at CSTEP, emphasised that “even modest ward-level investments in green infrastructure can yield substantial long-term savings and ecological benefits.” Her statement highlights that implementing NbS doesn’t always require large-scale or disruptive projects. Small, strategic interventions can collectively make a significant impact.

Policy Recommendations

The report strongly urges policymakers to embed nature-based solutions at the core of their climate resilience strategies. Among the key recommendations are:

• Updating Urban Planning Regulations: Urban bylaws need to be revised to mandate and facilitate NbS integration. For instance, building codes could include provisions for rooftop gardens, rainwater harvesting, and permeable surfaces.
  
• Prioritising Vulnerable Areas: NbS interventions should be targeted first in regions most susceptible to climate risks, such as low-lying neighborhoods and flood-prone zones.
  
• Allocating Public Funds: Governments must earmark funds specifically for green infrastructure projects. These investments are not just environmentally sound but fiscally prudent given their long-term returns.
  
• Community Involvement: For sustained success, local communities must be actively involved in the planning and maintenance of NbS. Public awareness campaigns and participatory planning can ensure better acceptance and stewardship.
  

Lessons for Other Coastal Cities

While the study focuses on Chennai and Mangaluru, the findings are relevant to other coastal cities like Mumbai, Visakhapatnam, Kochi, and Kolkata. These cities are also grappling with rapid urbanisation and climate-induced challenges. The framework presented by the report can serve as a replicable model for assessing and implementing NbS across various urban geographies in India.

As climate risks continue to mount, the limitations of conventional urban infrastructure are becoming increasingly evident. Nature-based solutions offer a powerful, multi-dimensional approach to building climate resilience while enhancing the livability and ecological health of cities. The report makes a compelling case for a fundamental shift in how Indian cities think about development, urging planners and policymakers to embrace nature not as an afterthought, but as a cornerstone of urban strategy.

References:

https://cstep.in/publications-details.php?id=3197

https://www.business-standard.com/india-news/nature-based-solutions-key-to-climate-resilience-in-coastal-cities-report-125042200498_1.html

https://www.nature.com/articles/s43247-024-01308-8#

https://www.sciencedirect.com/science/article/abs/pii/S004896972406892X

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