A Comparative Cost-Benefit Analysis of Nature-Based Solutions (NBS) Versus Hard Engineering for Urban Flood Resilience in the Lagos Coastal Region
DOI:
https://doi.org/10.56778/rss.v1i2.628Abstract
Lagos, Nigeria, faces systemic urban flooding exacerbated by rapid urbanization and climate change. This study conducts a systematic literature review (SLR) to comparatively analyze conventional Grey Infrastructure (GI) against Nature-Based Solutions (NBS) for flood resilience. Following a structured search of academic and grey literature from 2020–2024, data were synthesized across three lenses: policy context, functional effectiveness, and economic valuation. Results indicate that while GI provides immediate flood conveyance, it often lacks long-term adaptability and requires high maintenance. Conversely, NBS such as wetland restoration and urban green spaces exhibit superior lifecycle cost-efficiency and adaptive capacity. Findings reveal that the perceived economic superiority of GI is a methodological artifact of conventional Benefit-Cost Analysis (BCA), which undervalues environmental co-benefits. The study concludes that institutional fragmentation and infrastructure biases currently hinder NBS adoption in Lagos. To enhance resilience, targeted policy reforms are recommended, including the integration of comprehensive valuation frameworks that quantify ecosystem services and mandatory coordination between environmental and planning agencies.
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