A groundbreaking study from the University of Nairobi’s Department of Architecture and Building Science has proposed a comprehensive green infrastructure framework as the most viable solution to Nairobi’s chronic and worsening urban flooding. The research, which analyzed decades of urban planning data and hydrological patterns, concludes that the city’s traditional approach of channeling stormwater through concrete drains and sewers is fundamentally inadequate for the current climate reality. Instead, the study advocates for a systemic shift towards nature-based solutions that manage rainwater at its source, recommending the widespread implementation of green roofs, permeable pavements, bioswales, and the strategic expansion of urban wetlands to naturally absorb and slow down runoff before it overwhelms the city’s drainage systems.
The study provides a detailed technical and economic analysis, demonstrating how converting just 15% of Nairobi’s impervious surfaces to permeable alternatives could reduce peak stormwater flows by over 30%. It highlights specific high-risk flood hotspots, such as the Ngong River basin and areas of Eastlands, where targeted interventions like constructed wetlands could serve dual purposes: mitigating flood risk while creating public green spaces that improve air quality and community well-being. The research also emphasizes the critical need to protect and rehabilitate the city’s riparian reserves, which have been heavily encroached upon, noting that these natural corridors are essential for safely conveying floodwaters and are far more cost-effective to maintain than engineered concrete channels.
The long-term implementation of this green infrastructure vision would represent a paradigm shift in how Nairobi is managed and developed. The study’s authors call for the immediate integration of these principles into the city’s building codes, zoning regulations, and county development plans. While the initial investment is significant, the framework argues that the cost is far lower than the recurring economic losses from flood damage, infrastructure repair, and public health crises. By adopting this proactive, ecologically sensitive model, Nairobi has the opportunity to transform itself from a city besieged by its own runoff into a global leader in climate-resilient urban design, creating a more liveable, sustainable, and flood-resistant capital for future generations.